The document provides information about amoebiasis, including:
- It is caused by the parasitic protozoan Entamoeba histolytica, which can cause dysentery, colitis, and liver abscesses.
- The organism has a life cycle where cysts are ingested and excyst in the gut to the trophozoite stage, which can invade the colon and liver.
- Globally, amoebiasis is highly prevalent in developing tropical and subtropical countries where sanitation is poor, allowing transmission via contaminated food and water. It causes an estimated 40,000-100,000 deaths per year.
- Escherichia coli (E. coli) is a common bacteria that normally lives in the intestines of humans and animals. However, some strains of E. coli can cause illness, including diarrhea.
- E. coli that causes diarrhea is divided into six groups that produce diarrhea through different pathogenic mechanisms, such as the production of heat-stable or heat-labile toxins. One group, enterotoxigenic E. coli (ETEC), commonly causes travelers' diarrhea.
- In addition to diarrhea, E. coli can cause other illnesses like urinary tract infections, wound or blood infections, and even sepsis. The type of specimen collected for testing depends on the suspected infection.
Yersinia are gram-negative rods that can cause human disease. The document discusses Yersinia pestis, which causes plague, and Yersinia enterocolitica and Y. pseudotuberculosis, which cause human diarrheal diseases. Y. pestis is transmitted by fleas and causes a fatal infection if not treated with antibiotics like streptomycin. Y. enterocolitica and Y. pseudotuberculosis are transmitted through contaminated food or water and commonly cause self-limiting gastrointestinal infections but can occasionally spread systemically and cause more serious infections.
Botulism is caused by toxins produced by the bacterium Clostridium botulinum. It causes paralysis by blocking the release of acetylcholine at nerve endings. There are three main types: foodborne, wound, and infant botulism. Foodborne botulism results from ingesting preformed toxins in improperly canned or cooked foods. Wound botulism occurs when wounds are infected. Infant botulism usually affects children under 1 from ingesting spores. Symptoms include nausea, vomiting, paralysis starting with eyes and face. Treatment focuses on supportive care, antitoxin, and preventing further paralysis. Proper food preservation and handling can prevent botulism.
Cholera is a serious bacterial disease that usually
causes severe diarrhea and dehydration. The disease is typically spread through contaminated water.
Modern sewage and water treatment have effectively eliminated cholera in most countries. It’s still a problem in countries like Asia, America and Africa. Mostly in India.
Countries affected by war, poverty, and natural disasters have the greatest risk for a cholera outbreak.
Taxonomy:
class : Gamma Proteobacteria
Order: Vibrionales
Family: Vibrionaceae
Genus: Vibrio
Species: v.cholerae, v.parahaemolyticus,
v. vulnificus, v. alginolyticus
MORPHOLOGY:
Gram negative, actively motile, short, rigid curved bacilli
Resembling letter “V”
about 34 genus
most common in water
1.5µ X 0.2 -0.4 µ in size
polar flagellum , strongly aerobic
Smear – fish in stream appearance
PATHOGENESIS:
Source: Ingestion of contaminated water, food,
fruits and vegetables etc.,
Incubation periods: 1-5 days
Symptoms: Watery diarrhoea, vomiting, thirst, dehydration, muscle cramps
Complications: muscular pain, renal failure, pulmonary edema, cardiac arrhythrnias
DIAGNOSIS:
Specimen: stool sample, water sample(envt)
Microscopy: a) Hanging drop : +ve
b) Gram stain :-ve
Culture: Mac conkey Agar :colourless to light pink
TCBS : yellow colonies
Serology: serological tests are no diagnostic value
TREATMENT:
Adequate replacement of fluids and electrolytes.
Oral tetracycline reduces the period of vibrio excreation.
PREVENTION:
Drink and use bottled water
Frequent washing
Sanitary environment
Defecate in water
Cook food thoroughly
This document discusses Salmonella, including its isolation, morphology, cultural characteristics, biochemical activities, epidemiology, virulence factors, pathogenesis, clinical diseases, laboratory diagnosis, and treatment. Salmonella was first isolated in 1885 and causes diseases like typhoid fever, paratyphoid fever, and foodborne illness in humans. It is a gram-negative rod found in the intestines of animals and can contaminate foods. Diagnosis involves culturing specimens from blood, feces, urine or vomit. Treatment includes antibiotics like chloramphenicol, ampicillin, and ciprofloxacin.
1. Ascaris lumbricoides is the largest roundworm that commonly infects humans, inhabiting the small intestine. It is highly prevalent in areas with poor sanitation.
2. The adult worms can cause intestinal obstruction, while migrating larvae can cause aspiration pneumonia. Symptoms range from none to severe abdominal pain.
3. Diagnosis involves finding the eggs in stool samples. Treatment involves anthelmintic drugs like albendazole or mebendazole. Maintaining good sanitation is important for prevention.
The genus Shigella exclusively infects human intestine.
Shigella dysenteriae is the causative agent of bacillary dysentery or shigellosis in humans.
It is a diarrheal illness which is characterized by frequent passage of blood stained mucopurulent stools.
The four important species of the genus Shigella are:
Shigella dysenteriae
Shigella flexneri
Shigella sonnei
Shigella boydii.
- Escherichia coli (E. coli) is a common bacteria that normally lives in the intestines of humans and animals. However, some strains of E. coli can cause illness, including diarrhea.
- E. coli that causes diarrhea is divided into six groups that produce diarrhea through different pathogenic mechanisms, such as the production of heat-stable or heat-labile toxins. One group, enterotoxigenic E. coli (ETEC), commonly causes travelers' diarrhea.
- In addition to diarrhea, E. coli can cause other illnesses like urinary tract infections, wound or blood infections, and even sepsis. The type of specimen collected for testing depends on the suspected infection.
Yersinia are gram-negative rods that can cause human disease. The document discusses Yersinia pestis, which causes plague, and Yersinia enterocolitica and Y. pseudotuberculosis, which cause human diarrheal diseases. Y. pestis is transmitted by fleas and causes a fatal infection if not treated with antibiotics like streptomycin. Y. enterocolitica and Y. pseudotuberculosis are transmitted through contaminated food or water and commonly cause self-limiting gastrointestinal infections but can occasionally spread systemically and cause more serious infections.
Botulism is caused by toxins produced by the bacterium Clostridium botulinum. It causes paralysis by blocking the release of acetylcholine at nerve endings. There are three main types: foodborne, wound, and infant botulism. Foodborne botulism results from ingesting preformed toxins in improperly canned or cooked foods. Wound botulism occurs when wounds are infected. Infant botulism usually affects children under 1 from ingesting spores. Symptoms include nausea, vomiting, paralysis starting with eyes and face. Treatment focuses on supportive care, antitoxin, and preventing further paralysis. Proper food preservation and handling can prevent botulism.
Cholera is a serious bacterial disease that usually
causes severe diarrhea and dehydration. The disease is typically spread through contaminated water.
Modern sewage and water treatment have effectively eliminated cholera in most countries. It’s still a problem in countries like Asia, America and Africa. Mostly in India.
Countries affected by war, poverty, and natural disasters have the greatest risk for a cholera outbreak.
Taxonomy:
class : Gamma Proteobacteria
Order: Vibrionales
Family: Vibrionaceae
Genus: Vibrio
Species: v.cholerae, v.parahaemolyticus,
v. vulnificus, v. alginolyticus
MORPHOLOGY:
Gram negative, actively motile, short, rigid curved bacilli
Resembling letter “V”
about 34 genus
most common in water
1.5µ X 0.2 -0.4 µ in size
polar flagellum , strongly aerobic
Smear – fish in stream appearance
PATHOGENESIS:
Source: Ingestion of contaminated water, food,
fruits and vegetables etc.,
Incubation periods: 1-5 days
Symptoms: Watery diarrhoea, vomiting, thirst, dehydration, muscle cramps
Complications: muscular pain, renal failure, pulmonary edema, cardiac arrhythrnias
DIAGNOSIS:
Specimen: stool sample, water sample(envt)
Microscopy: a) Hanging drop : +ve
b) Gram stain :-ve
Culture: Mac conkey Agar :colourless to light pink
TCBS : yellow colonies
Serology: serological tests are no diagnostic value
TREATMENT:
Adequate replacement of fluids and electrolytes.
Oral tetracycline reduces the period of vibrio excreation.
PREVENTION:
Drink and use bottled water
Frequent washing
Sanitary environment
Defecate in water
Cook food thoroughly
This document discusses Salmonella, including its isolation, morphology, cultural characteristics, biochemical activities, epidemiology, virulence factors, pathogenesis, clinical diseases, laboratory diagnosis, and treatment. Salmonella was first isolated in 1885 and causes diseases like typhoid fever, paratyphoid fever, and foodborne illness in humans. It is a gram-negative rod found in the intestines of animals and can contaminate foods. Diagnosis involves culturing specimens from blood, feces, urine or vomit. Treatment includes antibiotics like chloramphenicol, ampicillin, and ciprofloxacin.
1. Ascaris lumbricoides is the largest roundworm that commonly infects humans, inhabiting the small intestine. It is highly prevalent in areas with poor sanitation.
2. The adult worms can cause intestinal obstruction, while migrating larvae can cause aspiration pneumonia. Symptoms range from none to severe abdominal pain.
3. Diagnosis involves finding the eggs in stool samples. Treatment involves anthelmintic drugs like albendazole or mebendazole. Maintaining good sanitation is important for prevention.
The genus Shigella exclusively infects human intestine.
Shigella dysenteriae is the causative agent of bacillary dysentery or shigellosis in humans.
It is a diarrheal illness which is characterized by frequent passage of blood stained mucopurulent stools.
The four important species of the genus Shigella are:
Shigella dysenteriae
Shigella flexneri
Shigella sonnei
Shigella boydii.
Escherichia coli is a common bacteria found in the intestines of humans and animals. While most E. coli strains are harmless, some can cause illness. There are several pathogenic types of E. coli including enterohemorrhagic E. coli (EHEC), enterotoxigenic E. coli (ETEC), enteroinvasive E. coli (EIEC), and enteropathogenic E. coli (EPEC). These pathogenic strains cause illnesses ranging from mild diarrhea to bloody diarrhea and even life-threatening complications like hemolytic uremic syndrome. Pathogenic E. coli are identified through tests of their genetic and phenotypic characteristics.
Amoebiasis is an infection caused by the protozoan Entamoeba histolytica. It is common in developing parts of the world with poor sanitation. Most infections are asymptomatic, but some can cause intestinal symptoms ranging from mild diarrhea to severe dysentery. Rarely, the infection can spread beyond the intestines and cause liver abscesses or affect other organs. Diagnosis involves microscopic examination of stool samples or biopsy specimens to look for trophozoites or cysts. Treatment depends on the severity of symptoms and may involve antibiotics or antiparasitic drugs. Prevention relies on improved sanitation, water treatment, hygiene and health education.
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive functioning. Exercise causes chemical changes in the brain that may help boost feelings of calmness, happiness and focus.
A 6-year-old girl presented with malnourishment, abdominal swelling, cough, wheeze and fever. Imaging revealed lobar pneumonia and suspicion of worms. Stool examination found Ascaris lumbricoides eggs. Ascaris lumbricoides is an intestinal roundworm that infects over 1 billion people worldwide. It is transmitted through ingestion of eggs from contaminated food, water or soil.
Shigella bacteria cause the infectious disease shigellosis or bacillary dysentery. It is estimated to cause around 90 million cases annually, resulting in over 100,000 deaths mostly in children in developing countries. The bacteria are highly contagious and can be transmitted through contaminated food or water. Symptoms include bloody diarrhea, abdominal cramps, and fever. Treatment involves rehydration and antibiotics to reduce duration of symptoms.
1) Ascaris lumbricoides, or the roundworm, is a large nematode that lives in the small intestine of humans.
2) The female roundworm can grow up to 40 cm long and lays eggs that are passed in feces.
3) The eggs develop into infective larvae outside the body under favorable conditions and can be swallowed, entering the lungs before migrating to the intestines where they mature into adult worms.
Trypanosomiasis is a vector-borne parasitic disease caused by Trypanosoma parasites. There are two main forms: African trypanosomiasis (sleeping sickness) transmitted by tsetse flies, and American trypanosomiasis (Chagas disease) transmitted by triatomine bugs. African trypanosomiasis is found in central and west Africa and causes a slow progression of symptoms, while American trypanosomiasis is found in Latin America and causes an initial acute phase followed by a chronic phase in some patients. Both forms require treatment with drugs to eliminate the parasites from the body.
This document discusses amoebiasis, a common intestinal infection caused by the parasite Entamoeba histolytica. It has a worldwide distribution and is a major health problem in areas with poor sanitation. Symptoms range from mild diarrhea to severe dysentery and liver abscesses. Diagnosis is made by identifying the parasite in stool samples. Treatment involves drugs like metronidazole. Prevention relies on improved sanitation, safe food and water, health education, and treatment of carriers like food handlers.
This document discusses Escherichia coli (E. coli), a common bacterium found in the intestines of humans and animals. It describes E. coli's morphology, identification, and ability to cause diseases like urinary tract infections, neonatal meningitis, and intestinal diseases. Prevention methods are outlined, including good hygiene practices like handwashing and thoroughly cooking meats to avoid transmission. Treatment focuses on fluid replacement rather than antibiotics in most cases unless the disease has progressed to a systemic stage.
This document discusses histoplasmosis, an infection caused by the fungus Histoplasma capsulatum. The fungus lives in soil containing bird or bat droppings. There are two main types - pulmonary histoplasmosis, which occurs when the fungus is inhaled, and disseminated histoplasmosis, which spreads from the lungs. Symptoms can include fever, cough, fatigue and chest pain. Diagnosis involves examining samples under a microscope for the yeast cells or culturing samples. Treatment uses antifungal medications such as itraconazole or amphotericin B, depending on severity.
Eschericia coli is a gram-negative, facultative anaerobic bacterium that is commonly found in the lower intestine of warm-blooded organisms. It can cause several types of infections including urinary tract infections, enteric infections like traveler's diarrhea, and other rare infections. Laboratory diagnosis involves microscopic examination of samples showing gram-negative bacilli, as well as culture-based identification using selective media and biochemical tests to confirm lactose fermentation and other properties. Treatment depends on the severity and type of infection, ranging from supportive care to antibiotics for serious complications.
1) Schistosomiasis, also known as bilharzia or snail fever, is a disease caused by parasitic flatworms (trematode worms) of the genus Schistosoma.
2) It is found most commonly in Africa, South America, East Asia, and the Middle East, infecting over 230 million people annually, with over 90% of cases occurring in Africa.
3) The parasite has a complex lifecycle involving freshwater snails and human hosts. People become infected when larval forms of the parasite penetrate their skin during contact with infected water, then develop into adults that reside in blood vessels, releasing eggs that can cause damage to internal organs.
Leishmaniasis is a parasitic disease spread by sand fly bites. It exists in three main forms: cutaneous, mucocutaneous, and visceral. Cutaneous lesions cause skin sores, while mucocutaneous lesions affect mucosal tissues and can cause disfigurement. Visceral leishmaniasis affects internal organs and is the most serious form. The disease is diagnosed by microscopic examination of tissues or cultures to view the parasites. Treatment depends on the form but may include topical or systemic antimonials, amphotericin B, or miltefosine.
Shigellosis = inflammation of intestines (especially the colon) with accompanying severe abdominal cramps, tenesmus and frequent, low-volume stools containing blood, mucus and fecal leukocytes.
Coxiella burnetii is an obligate intracellular bacterium that causes Q fever in humans and animals. It is distributed worldwide and the primary reservoirs are cattle, sheep and goats. Transmission to humans occurs mainly through inhalation of aerosols from infected animal birth products. Infection in humans ranges from asymptomatic to an acute flu-like illness or chronic conditions like endocarditis. Diagnosis involves serologic tests or PCR. Tetracycline is used to treat acute Q fever in humans. Vaccination of animals and pasteurization of dairy products can help control spread.
Yersinia pestis is a gram-negative rod that causes plague. It is primarily transmitted between rodents like rats, mice and squirrels via flea bites. Humans are accidental hosts. There are three main forms of plague infection: bubonic plague causes swollen lymph nodes, septicemic plague causes fever and hypotension, and pneumonic plague causes cough and bloody sputum. Yersinia enterocolitica and Y. pseudotuberculosis can cause gastrointestinal illness in humans after consuming contaminated food, especially pork.
Helminthic infections are caused by parasitic worms. Successful parasites live in and obtain nutrients from the host without killing it. The severity of disease depends on the parasite burden and host immune response. Parasites enter through ingestion, arthropod bites, or skin/mucous membrane penetration. Some parasites must migrate within the host to complete their lifecycle, but non-human parasites in humans often become dead-end infections. Mechanisms of evading the immune response include antigenic variation, intracellular infection, encystation, and camouflage. Tissue damage results from direct destruction, hypersensitivity reactions, or eosinophilia during migration. Helminths are classified as nematodes, trematodes
Cryptosporidium parvum is an enteric parasite that is one of the most common causes of diarrhea worldwide. It is transmitted through the fecal-oral route, often through contact with contaminated water. The oocyst stage of its life cycle is very resilient and can survive in water even after treatment. Infection occurs when an oocyst embeds itself in the gut epithelium. There is no cure for immunocompromised individuals who become infected.
1) The patient, a 41-year-old male, has been feeling drunk and unable to walk properly or think clearly for several weeks.
2) Lyme disease is caused by the bacteria Borrelia burgdorferi, which is transmitted through the bite of infected blacklegged ticks.
3) The presentation of symptoms depends on the stage of infection, ranging from a bullseye rash in the early localized stage to neurological or heart problems in later disseminated stages.
This document discusses Leishmania, a genus of parasitic protozoa that causes leishmaniasis. It is transmitted by sandflies and is endemic in over 80 countries. The clinical manifestations range from cutaneous leishmaniasis causing skin lesions, to mucocutaneous leishmaniasis affecting mucous membranes, to visceral leishmaniasis affecting internal organs. Diagnosis involves direct identification of the parasite or antibodies. Treatment depends on the form of the disease.
Amoebiasis is caused by the intestinal protozoan Entamoeba histolytica. Most infections are asymptomatic, but 10% can cause a spectrum of clinical syndromes ranging from asymptomatic to dysentery to liver and other organ abscesses. Transmission occurs through the fecal-oral route via contaminated food, water, or direct person-to-person contact. Diagnosis involves microscopic identification of trophozoites in stool or abscess samples and serologic detection of antibodies. Treatment depends on the infection site and involves luminal amoebicides for intestinal infection and tissue amoebicides like metronidazole for extra-intestinal infections such as liver abscesses.
This document provides information on microbiology and parasitology. It discusses microorganisms like bacteria, parasites, fungi and viruses. It also describes different types of parasites including protozoa and helminths. Specifically, it summarizes the life cycle, symptoms, diagnosis and treatment of Entamoeba histolytica, which causes amoebiasis. It notes that amoebiasis is common in developing countries where sanitation is poor and transmission occurs through the fecal-oral route by ingesting cysts from contaminated food or water. Stool examination is used to diagnose by identifying trophozoites or cysts of E. histolytica.
Escherichia coli is a common bacteria found in the intestines of humans and animals. While most E. coli strains are harmless, some can cause illness. There are several pathogenic types of E. coli including enterohemorrhagic E. coli (EHEC), enterotoxigenic E. coli (ETEC), enteroinvasive E. coli (EIEC), and enteropathogenic E. coli (EPEC). These pathogenic strains cause illnesses ranging from mild diarrhea to bloody diarrhea and even life-threatening complications like hemolytic uremic syndrome. Pathogenic E. coli are identified through tests of their genetic and phenotypic characteristics.
Amoebiasis is an infection caused by the protozoan Entamoeba histolytica. It is common in developing parts of the world with poor sanitation. Most infections are asymptomatic, but some can cause intestinal symptoms ranging from mild diarrhea to severe dysentery. Rarely, the infection can spread beyond the intestines and cause liver abscesses or affect other organs. Diagnosis involves microscopic examination of stool samples or biopsy specimens to look for trophozoites or cysts. Treatment depends on the severity of symptoms and may involve antibiotics or antiparasitic drugs. Prevention relies on improved sanitation, water treatment, hygiene and health education.
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive functioning. Exercise causes chemical changes in the brain that may help boost feelings of calmness, happiness and focus.
A 6-year-old girl presented with malnourishment, abdominal swelling, cough, wheeze and fever. Imaging revealed lobar pneumonia and suspicion of worms. Stool examination found Ascaris lumbricoides eggs. Ascaris lumbricoides is an intestinal roundworm that infects over 1 billion people worldwide. It is transmitted through ingestion of eggs from contaminated food, water or soil.
Shigella bacteria cause the infectious disease shigellosis or bacillary dysentery. It is estimated to cause around 90 million cases annually, resulting in over 100,000 deaths mostly in children in developing countries. The bacteria are highly contagious and can be transmitted through contaminated food or water. Symptoms include bloody diarrhea, abdominal cramps, and fever. Treatment involves rehydration and antibiotics to reduce duration of symptoms.
1) Ascaris lumbricoides, or the roundworm, is a large nematode that lives in the small intestine of humans.
2) The female roundworm can grow up to 40 cm long and lays eggs that are passed in feces.
3) The eggs develop into infective larvae outside the body under favorable conditions and can be swallowed, entering the lungs before migrating to the intestines where they mature into adult worms.
Trypanosomiasis is a vector-borne parasitic disease caused by Trypanosoma parasites. There are two main forms: African trypanosomiasis (sleeping sickness) transmitted by tsetse flies, and American trypanosomiasis (Chagas disease) transmitted by triatomine bugs. African trypanosomiasis is found in central and west Africa and causes a slow progression of symptoms, while American trypanosomiasis is found in Latin America and causes an initial acute phase followed by a chronic phase in some patients. Both forms require treatment with drugs to eliminate the parasites from the body.
This document discusses amoebiasis, a common intestinal infection caused by the parasite Entamoeba histolytica. It has a worldwide distribution and is a major health problem in areas with poor sanitation. Symptoms range from mild diarrhea to severe dysentery and liver abscesses. Diagnosis is made by identifying the parasite in stool samples. Treatment involves drugs like metronidazole. Prevention relies on improved sanitation, safe food and water, health education, and treatment of carriers like food handlers.
This document discusses Escherichia coli (E. coli), a common bacterium found in the intestines of humans and animals. It describes E. coli's morphology, identification, and ability to cause diseases like urinary tract infections, neonatal meningitis, and intestinal diseases. Prevention methods are outlined, including good hygiene practices like handwashing and thoroughly cooking meats to avoid transmission. Treatment focuses on fluid replacement rather than antibiotics in most cases unless the disease has progressed to a systemic stage.
This document discusses histoplasmosis, an infection caused by the fungus Histoplasma capsulatum. The fungus lives in soil containing bird or bat droppings. There are two main types - pulmonary histoplasmosis, which occurs when the fungus is inhaled, and disseminated histoplasmosis, which spreads from the lungs. Symptoms can include fever, cough, fatigue and chest pain. Diagnosis involves examining samples under a microscope for the yeast cells or culturing samples. Treatment uses antifungal medications such as itraconazole or amphotericin B, depending on severity.
Eschericia coli is a gram-negative, facultative anaerobic bacterium that is commonly found in the lower intestine of warm-blooded organisms. It can cause several types of infections including urinary tract infections, enteric infections like traveler's diarrhea, and other rare infections. Laboratory diagnosis involves microscopic examination of samples showing gram-negative bacilli, as well as culture-based identification using selective media and biochemical tests to confirm lactose fermentation and other properties. Treatment depends on the severity and type of infection, ranging from supportive care to antibiotics for serious complications.
1) Schistosomiasis, also known as bilharzia or snail fever, is a disease caused by parasitic flatworms (trematode worms) of the genus Schistosoma.
2) It is found most commonly in Africa, South America, East Asia, and the Middle East, infecting over 230 million people annually, with over 90% of cases occurring in Africa.
3) The parasite has a complex lifecycle involving freshwater snails and human hosts. People become infected when larval forms of the parasite penetrate their skin during contact with infected water, then develop into adults that reside in blood vessels, releasing eggs that can cause damage to internal organs.
Leishmaniasis is a parasitic disease spread by sand fly bites. It exists in three main forms: cutaneous, mucocutaneous, and visceral. Cutaneous lesions cause skin sores, while mucocutaneous lesions affect mucosal tissues and can cause disfigurement. Visceral leishmaniasis affects internal organs and is the most serious form. The disease is diagnosed by microscopic examination of tissues or cultures to view the parasites. Treatment depends on the form but may include topical or systemic antimonials, amphotericin B, or miltefosine.
Shigellosis = inflammation of intestines (especially the colon) with accompanying severe abdominal cramps, tenesmus and frequent, low-volume stools containing blood, mucus and fecal leukocytes.
Coxiella burnetii is an obligate intracellular bacterium that causes Q fever in humans and animals. It is distributed worldwide and the primary reservoirs are cattle, sheep and goats. Transmission to humans occurs mainly through inhalation of aerosols from infected animal birth products. Infection in humans ranges from asymptomatic to an acute flu-like illness or chronic conditions like endocarditis. Diagnosis involves serologic tests or PCR. Tetracycline is used to treat acute Q fever in humans. Vaccination of animals and pasteurization of dairy products can help control spread.
Yersinia pestis is a gram-negative rod that causes plague. It is primarily transmitted between rodents like rats, mice and squirrels via flea bites. Humans are accidental hosts. There are three main forms of plague infection: bubonic plague causes swollen lymph nodes, septicemic plague causes fever and hypotension, and pneumonic plague causes cough and bloody sputum. Yersinia enterocolitica and Y. pseudotuberculosis can cause gastrointestinal illness in humans after consuming contaminated food, especially pork.
Helminthic infections are caused by parasitic worms. Successful parasites live in and obtain nutrients from the host without killing it. The severity of disease depends on the parasite burden and host immune response. Parasites enter through ingestion, arthropod bites, or skin/mucous membrane penetration. Some parasites must migrate within the host to complete their lifecycle, but non-human parasites in humans often become dead-end infections. Mechanisms of evading the immune response include antigenic variation, intracellular infection, encystation, and camouflage. Tissue damage results from direct destruction, hypersensitivity reactions, or eosinophilia during migration. Helminths are classified as nematodes, trematodes
Cryptosporidium parvum is an enteric parasite that is one of the most common causes of diarrhea worldwide. It is transmitted through the fecal-oral route, often through contact with contaminated water. The oocyst stage of its life cycle is very resilient and can survive in water even after treatment. Infection occurs when an oocyst embeds itself in the gut epithelium. There is no cure for immunocompromised individuals who become infected.
1) The patient, a 41-year-old male, has been feeling drunk and unable to walk properly or think clearly for several weeks.
2) Lyme disease is caused by the bacteria Borrelia burgdorferi, which is transmitted through the bite of infected blacklegged ticks.
3) The presentation of symptoms depends on the stage of infection, ranging from a bullseye rash in the early localized stage to neurological or heart problems in later disseminated stages.
This document discusses Leishmania, a genus of parasitic protozoa that causes leishmaniasis. It is transmitted by sandflies and is endemic in over 80 countries. The clinical manifestations range from cutaneous leishmaniasis causing skin lesions, to mucocutaneous leishmaniasis affecting mucous membranes, to visceral leishmaniasis affecting internal organs. Diagnosis involves direct identification of the parasite or antibodies. Treatment depends on the form of the disease.
Amoebiasis is caused by the intestinal protozoan Entamoeba histolytica. Most infections are asymptomatic, but 10% can cause a spectrum of clinical syndromes ranging from asymptomatic to dysentery to liver and other organ abscesses. Transmission occurs through the fecal-oral route via contaminated food, water, or direct person-to-person contact. Diagnosis involves microscopic identification of trophozoites in stool or abscess samples and serologic detection of antibodies. Treatment depends on the infection site and involves luminal amoebicides for intestinal infection and tissue amoebicides like metronidazole for extra-intestinal infections such as liver abscesses.
This document provides information on microbiology and parasitology. It discusses microorganisms like bacteria, parasites, fungi and viruses. It also describes different types of parasites including protozoa and helminths. Specifically, it summarizes the life cycle, symptoms, diagnosis and treatment of Entamoeba histolytica, which causes amoebiasis. It notes that amoebiasis is common in developing countries where sanitation is poor and transmission occurs through the fecal-oral route by ingesting cysts from contaminated food or water. Stool examination is used to diagnose by identifying trophozoites or cysts of E. histolytica.
Amoebiasis by bhanu chalise, iom maharajgunjaviralchalise
Amebiasis is caused by the protozoan Entamoeba histolytica and is a major public health problem globally. It is commonly found in developing tropical and subtropical countries where poverty, poor sanitation, and malnutrition are prevalent risk factors. E. histolytica infection may be asymptomatic or may cause intestinal disease ranging from mild diarrhea to severe colitis or extraintestinal infections such as amoebic liver abscess. Diagnosis involves identification of trophozoites or cysts in stool samples or detection of antibodies or antigens in blood tests. Treatment involves luminal agents such as metronidazole to eliminate active infections and tissue amoebicides such as diloxanide furoate to clear cyst
This document provides an overview of amoebiasis (Entamoeba histolytica infection). It discusses the definition, life cycle, epidemiology, pathogenesis, clinical manifestations, diagnosis and treatment of intestinal amoebiasis as well as extra-intestinal infections such as amoebic liver abscess. Key points include that 90% of E. histolytica infections are asymptomatic but 10% can cause intestinal or extraintestinal disease ranging from dysentery to liver abscesses. Diagnosis involves microscopy of stool, biopsy or abscess aspirate samples. Treatment depends on the clinical presentation and involves metronidazole and other drugs.
This document summarizes information about amoebiasis, an infection caused by the parasite Entamoeba histolytica. It is transmitted through the fecal-oral route or by ingesting contaminated food or water. Symptoms can range from mild diarrhea to severe dysentery with blood and mucus. The amoeba can invade the intestinal wall and spread to the liver or other organs. Diagnosis is made by finding cysts in stool samples. Prevention involves proper handwashing, water treatment, and avoiding unsafe foods. Treatment consists of antibiotics like metronidazole or tinidazole to eliminate the parasite.
This document discusses amoebiasis, an infection caused by the parasite Entamoeba histolytica. It can cause abdominal pains, diarrhea, or constipation. While most infected people do not show symptoms, it can be fatal for babies and older people. It kills 70,000 people worldwide each year. The parasite lives in the digestive system and is transmitted through contaminated food, water, or contact with infected feces. Treatment involves anti-protozoal medications, and prevention focuses on proper handwashing and sanitation.
Abdul ppt smnr ; u can contact me mannanhkd4@gmail.commicrohicc
Amoebiasis is an infectious disease caused by the parasite Entamoeba histolytica. It commonly causes diarrhea, fever, and abdominal cramps by infecting the intestines. It may also spread to other organs like the liver. The disease is transmitted through contaminated food or water. Diagnosis involves microscopic examination of stool samples or antibody/antigen tests. Treatment depends on the infected organ but may involve antibiotics for intestinal infections or drainage and antibiotics for liver abscesses.
This document summarizes amoebiasis, caused by the protozoan Entamoeba histolytica. It is prevalent in warm climates with unsanitary areas and is acquired by swallowing cysts. The cysts can survive a few days outside the body and pass into the intestines, where they may invade tissues and form liver abscesses. Symptoms include diarrhea, abdominal pain, and tenderness. Treatment involves antibiotics like metronidazole and prevention focuses on sanitation, water purification, and hygiene.
This document summarizes Entamoeba histolytica, the causative agent of amoebiasis. It causes infection via fecal-oral transmission or oral sex. Virulence is determined by strain characteristics and host immunity. The parasite infects the intestine, where it may cause lesions and ulceration. It can spread to other organs like the liver to cause abscesses. Liver abscesses typically appear as solitary masses in the right lobe and contain anchovy sauce-like pus. The parasite may also infect the brain, skin or urogenital tract in rare cases.
1. The document discusses principles of geometrical optics including pinhole imaging, mirrors, lenses, and light propagation.
2. Key terms are defined such as object and image characteristics, magnification, and refractive index.
3. Principles of reflection, refraction, and dispersion are explained according to Snell's law and the refractive indices of common optical materials.
This document discusses various types of optical aberrations including chromatic aberration, spherical aberration, oblique aberration, coma, and image distortion. It explains how each aberration occurs in optical systems and the eye. Methods for correcting aberrations are also presented, such as using lenses of different materials or aspherical surfaces to reduce chromatic and spherical aberration. The eye has natural mechanisms for reducing the impact of many aberrations on vision.
The document describes symptoms and treatments for several tropical diseases and illnesses. It provides information on Hepatitis A & B, Typhoid Fever, Malaria, Dengue Fever, Japanese Encephalitis, Meningitis, Rabies, Tetanus, Intestinal Parasites, Cholera, and Tuberculosis. For each disease, it lists common symptoms and then provides a brief overview of causes, prognosis, and typical treatments. The document serves as a reference for understanding and managing various infectious tropical diseases.
This document discusses various types of optical aberrations that occur when light passes through a lens. It describes six main types of aberrations: chromatic aberration, spherical aberration, marginal astigmatism, coma, curvature of field, and distortion. For each aberration, it explains the visual effects, causes, importance for eyeglass lens design, and potential corrections. The document provides an in-depth overview of how different lens properties and light behaviors can lead to imperfect focusing and imaging within the eye.
1. The document discusses common surgical conditions seen in tropical regions, including typhoid, tuberculosis, amoebiasis, ascariasis, and tropical diseases.
2. It provides details on the pathogenesis, clinical presentation, diagnosis, and treatment of typhoid perforation, ascariasis infection and obstruction, and amoebic liver abscess.
3. The document emphasizes that patients in tropical regions often do not seek medical help until diseases have progressed significantly, sometimes resulting in emergency presentations of conditions like typhoid perforation or ascariasis obstruction.
Intestinal amoebiasis presents with abdominal pain and tenderness, diarrhea, and painful bowel movements over 1-several weeks. Mild cases show mucus diarrhea without blood, while severe cases have bloody, bulky stools with fever and cramps. Physical exam may reveal hepatomegaly, localized tenderness, rales, jaundice, or epigastric tenderness. Extra-intestinal amoebiasis can cause liver abscess, skin lesions, or infection of other organs.
Entamoeba histolytica is a protozoan parasite that causes amoebiasis through fecal-oral transmission. It has a lifecycle involving an infective cyst stage and pathogenic trophozoite stage. Trophozoites cause intestinal and extra-intestinal disease through virulence factors like cysteine proteases. Symptoms range from mild diarrhea to severe colitis, liver abscesses, or other extra-intestinal complications. Diagnosis involves microscopy, antigen detection in stool, or serology. Treatment involves luminal agents like diloxanide furoate or tissue agents like metronidazole. Prevention relies on proper hygiene and sanitation practices.
Amoebic dysentery, also known as amoebiasis, is an intestinal inflammation caused by the parasite Entamoeba histolytica found in contaminated food and water. It commonly affects those in less developed countries and travelers who visit areas with poor sanitation. Symptoms range from mild abdominal cramps and diarrhea to more severe bloody stools and fever. Treatment involves antibiotics like metronidazole to kill the parasite, while complications can include liver abscesses if the infection spreads.
Amebiasis is caused by the protozoan Entamoeba histolytica. It commonly causes asymptomatic intestinal infection but can also cause intestinal disease ranging from dysentery to liver abscesses. The parasite exists in two forms - a motile trophozoite form and a cyst form. Infection occurs through ingestion of cysts in contaminated food or water. Most infections are asymptomatic, but 10% can cause intestinal or extraintestinal disease. Diagnosis involves stool examination and serology. Treatment involves luminal agents for intestinal infection and metronidazole or tinidazole for invasive disease. Surgery may be needed for complications like perforation or toxic megacolon.
This document provides information on Entamoeba histolytica, a pathogenic protozoan parasite. It outlines the etiology, epidemiology, pathogenesis, clinical manifestations, diagnosis, treatment, and complications of E. histolytica infection. Key points include:
- E. histolytica infects up to 10% of the world's population and is a major cause of parasitic death. It typically causes asymptomatic colonization but can lead to amebic colitis or liver abscess.
- Infection occurs through ingestion of cysts in contaminated food/water. Cysts excyst in the intestine and trophozoites may invade the colonic mucosa.
- Diagnosis involves antigen detection in stool
A 20-year-old female developed abdominal cramps and bloody diarrhea after eating at a restaurant. Testing revealed she was infected with Entamoeba histolytica, the causative agent of amebiasis. E. histolytica has a life cycle involving an infectious cyst form and an invasive trophozoite form. Treatment involves antibiotics to eliminate the trophozoites, followed by additional medication to clear the cysts from the intestines.
The document discusses the anatomy, development, function, and clinical presentation of appendicitis of the appendix. It describes the appendix as a thin tube located in the lower right abdomen that develops from the cecum and contains lymphoid tissue. While its function was originally unknown, it is now believed to play a role in immune function as lymphoid tissue accumulates after birth, exposing white blood cells to antigens from the gastrointestinal tract. Acute appendicitis occurs when the appendix becomes blocked and infected, most commonly from lymphoid hyperplasia or fecaliths. Clinical features include abdominal pain that localizes to the right lower quadrant along with nausea, vomiting, and fever. Diagnosis involves examination
The document discusses the anatomy, development, and functions of the appendix. It begins by describing how the appendix was first described in 1889 and its typical location in the lower right abdomen attached to the cecum. It then discusses how the appendix acts as lymphoid tissue and may help the immune system by exposing white blood cells to antigens in the gastrointestinal tract. The document also covers acute appendicitis, including symptoms, investigations, and treatments like appendectomy. It notes the appendix's role may decrease with age after the third decade.
Cryptosporidium exhibits a monoxenous lifecycle and affects both humans and animals. Infected domestic animals are reservoirs for susceptible humans. in the lifecycle of the cryptosporidium, Thin-wall oocyst (used for autoinfection) and Thick wall oocyst are (thrown into the environment for infecting another host). Invaginate cell membrane and forming #bi-layered membranous vacuole (parasitophorous vacuolar membrane) creates a conducive environment for the parasite for escaping the host immune system.
Amebiasis is a disease caused by a one-celled parasite called Entamoeba histolytica (ent-a-ME-ba his-to-LI-ti-ka).
Who is at risk for amebiasis?
Although anyone can have this disease, it is most common in people who live in developing countries that have poor sanitary conditions. In the United States, amebiasis is most often foundin immigrants from developing countries. It also is found in people who have traveled to developing countries and in people who live in institutions that have poor sanitary conditions. Men who have sex with men can become infected and can get sick from the infection, but they often do not have symptoms.
by Mostafa Mohammadzadeh fallah (MedStudent Iran)
This document provides information about protozoology and the parasitic protozoan Entamoeba histolytica. It begins with an introduction to protozoology and classifications of protozoa. It then discusses the general characteristics, life cycles, and importance of protozoa. The document focuses on E. histolytica, outlining its habitat, transmission, morphology, life cycle within the human host, virulence factors, epidemiology, pathogenesis, symptoms of infection, laboratory diagnosis, treatment and prevention. E. histolytica causes amebiasis and can lead to intestinal or extraintestinal disease such as liver abscesses if the parasite invades tissues.
Entamoeba histolytica infects hundreds of millions worldwide, particularly in tropical areas with poor sanitation like Kenya. It typically causes no symptoms but can manifest as intestinal amoebiasis (amoebic colitis) or extra-intestinal amoebic liver abscess. Transmission is through the fecal-oral route via contaminated food, water, or direct contact. Diagnosis involves microscopic identification of trophozoites in stool or serologic antibody tests. Treatment depends on disease severity and involves metronidazole with or without paromomycin or diloxanide furoate. Complications can include necrotizing colitis, ameboma, liver abscess rupture, or extra
Entamoeba histolytica is a pathogenic amoeba that causes amoebiasis (amoebic dysentery). It has two forms - an invasive trophozoite form and a cyst form which is the infectious stage. The cyst can survive for weeks in the environment. Up to 10% of infected individuals develop intestinal or extra-intestinal disease. Symptoms of intestinal disease include diarrhea with blood or mucus while extra-intestinal disease involves the liver or lungs. Diagnosis involves identifying the trophozoites or cysts in stool samples. Treatment is with metronidazole or tinidazole. Prevention focuses on improved sanitation, safe water and hygiene education to prevent fecal-oral
This document discusses different types of cystic diseases of the liver, including pyogenic liver abscess, amebic liver abscess, and hydatid liver cyst. It covers the etiology, risk factors, clinical presentation, diagnosis, and treatment of each condition. Pyogenic liver abscess was initially thought to be caused by appendicitis but is now understood to often have a biliary origin. Amebic liver abscess is caused by Entamoeba histolytica infection transmitted via contaminated food or water. Hydatid cyst results from Echinococcus granulosus infection through contact with dogs that are the definitive host.
This document discusses medically important protozoa, including their classification, epidemiology, morphology, lifecycles, pathogenesis, clinical manifestations, diagnosis, treatment, and prevention. It focuses on Entamoeba histolytica, providing details on its lifecycle involving the ingestion of cysts, excystation in the intestines, tissue invasion via trophozoites, and formation of cysts that are passed in feces. Symptoms of E. histolytica infection range from asymptomatic carriage to intestinal amebiasis and extraintestinal amebiasis involving the liver and other organs. Diagnosis involves cyst examination in stool and antigen detection, while treatment involves metronidazole and other agents depending on
Shigella are gram-negative, facultative anaerobic bacteria that are a major cause of bacillary dysentery. There are four species - S. sonnei, S. flexneri, S. boydii, and S. dysenteriae. Shigella invade the colonic epithelium and multiply intracellularly, evading antibody-mediated immunity. They produce Shiga toxin which is enterotoxic, neurotoxic, and cytotoxic, causing the symptoms seen in shigellosis like diarrhea, fever, and bloody dysentery. Person-to-person fecal-oral transmission is common, often in settings like daycare centers and developing countries. Treatment involves rehydration, antibiotics
Shigella are gram-negative, facultative anaerobic bacteria that are a major cause of bacillary dysentery. There are four species - S. sonnei, S. flexneri, S. boydii, and S. dysenteriae. Shigella invade the colonic epithelium and multiply intracellularly, evading antibody-mediated immunity. They produce Shiga toxin which is enterotoxic, neurotoxic, and cytotoxic, causing the symptoms seen in shigellosis like diarrhea, fever, and bloody dysentery. Person-to-person fecal-oral transmission is common, often in settings like daycare centers and developing countries. Treatment involves rehydration, antibiotics
The document summarizes the gastrointestinal tract and infections that can occur within it. It describes the host defenses of the GI tract and normal microflora. Specific pathogens that can cause diarrhea are discussed such as Vibrio cholerae, Escherichia coli, rotavirus, and others. The mechanisms of how these pathogens cause infection and diarrhea are also summarized.
Giardiasis is caused by the intestinal parasite Giardia lamblia. It commonly causes epidemic and endemic diarrhea worldwide. The life cycle involves a trophozoite stage that colonizes the small intestine and a cyst stage that is passed in feces and can survive for months in the environment. Symptoms range from asymptomatic cyst passage to acute or chronic diarrhea. Diagnosis is made by identifying cysts or trophozoites in stool samples. Treatment involves antimicrobial drugs. Prevention focuses on proper water treatment and hygiene practices.
This document discusses liver abscesses, including types (pyogenic, amoebic, fungal), causes, risk factors, symptoms, diagnostic tests, and treatment. Pyogenic liver abscess is most common, often caused by bacteria spreading from infections in other organs. Amoebic liver abscess is caused by a parasite and presents with thick pus. Imaging tests can identify abscesses, which are usually treated with antibiotics; drainage may be needed for large abscesses. With treatment, prognosis is generally good especially for amoebic liver abscess.
This document provides information about amoebiasis caused by Entamoeba histolytica. It discusses the life cycle, symptoms, diagnosis and treatment. Regarding life cycle, E. histolytica has stages of cysts which are ingested and release trophozoites in the intestines. Trophozoites colonize the intestines and form cysts which are released causing further infections. Symptoms range from asymptomatic to dysentery and liver abscesses. Diagnosis involves examining stool for cysts/trophozoites and imaging abscesses. Treatment includes metronidazole or tinidazole antibiotics. Prevention relies on proper sanitation and water treatment to avoid fecal-oral transmission.
Amoebiasis is caused by the parasite Entamoeba histolytica. It infects the intestinal lining and can cause dysentery or amoebic colitis. In severe cases, it can lead to liver or brain abscesses. Diagnosis involves microscopic examination of stool samples to look for the motile trophozoites or cysts of E. histolytica. Specific diagnosis requires demonstrating the invasive trophozoites that may contain ingested red blood cells. Amoebiasis remains common in developing tropical areas with poor sanitation but can infect travelers as well.
La Entamoeba histolytica es un parásito protozoario que puede presentarse en forma de trofozoíto, quiste o metaquiste. El trofozoíto existe en forma minuta no patógena o forma magna altamente patógena que se alimenta por fagocitosis e ingiere glóbulos rojos. El quiste es la forma infectante con alta resistencia que contiene 1-4 núcleos.
This document provides information about amebiasis (amebic dysentery), caused by the protozoan Entamoeba histolytica. It discusses the causal agent, geographic distribution, morphology, life cycle, epidemiology, transmission, pathogenesis, clinical symptoms, diagnosis, treatment, and pathology of intestinal and extraintestinal amebiasis. Key points include that amebiasis is widespread in developing countries and causes an estimated 50,000-100,000 deaths annually, and that differentiating E. histolytica from the nonpathogenic E. dispar requires identification of erythrophagocytosis or molecular/immunological methods.
This document discusses the diagnosis and treatment of vaginitis, including bacterial vaginosis (BV), vulvovaginal candidiasis, and trichomoniasis. BV is caused by an overgrowth of anaerobic bacteria that normally inhabit the vagina and results in a grayish discharge and abnormal vaginal pH. Risk factors include douching, IUD use, younger age, and multiple sex partners. Diagnosis is based on Amsel's criteria or Gram stain morphology. Treatment involves oral or topical antibiotics like metronidazole or clindamycin.
This document provides information about amebiasis (amebic dysentery), caused by the protozoan Entamoeba histolytica. It discusses the causal agent, geographic distribution, morphology, life cycle, epidemiology, transmission, pathogenesis, clinical symptoms, diagnosis, treatment, and pathology of intestinal and extraintestinal amebiasis. Key points include that amebiasis is widespread in developing countries and causes an estimated 50,000-100,000 deaths annually, and that differentiating E. histolytica from the nonpathogenic E. dispar requires identification of erythrophagocytosis or molecular/immunological methods.
This document summarizes information about Entamoeba histolytica, the causative agent of amoebiasis. It discusses the global prevalence and trends of the disease, describing it as the third most common parasitic cause of death worldwide. The document outlines the lifecycle and transmission of E. histolytica, describing its two infectious forms - the trophozoite and cyst. It also summarizes the clinical manifestations of amoebiasis, which can range from asymptomatic carriage to amoebic colitis or liver abscesses. The diagnosis, treatment, prevention and control of amoebiasis are also briefly discussed.
This document summarizes information about amebiasis, an intestinal infection caused by the protozoan Entamoeba histolytica. It discusses the organism's lifecycle and symptoms of infection, which can include diarrhea and liver abscesses. The document also outlines methods for diagnosing amebiasis and treatments including metronidazole and tinidazole. It notes that improved sanitation and access to clean water have decreased rates of amebiasis.
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Amoebiasis
E-Learning Module Click here to
begin
Clinical SummaryIntroduction EpidemiologyDisease biology
Matt Pugh
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Introduction
Welcome to the amoebiasis e-learning module. Amoebiasis is a
parasitic protozoan disease that affects the gut mucosa and liver,
resulting in dysentery, colitis and liver abscess. The causative
agent, Entamoeba histolytica, is a potent pathogen that is spread via
ingestion of contaminated food and water. Globally, amoebiasis is
highly prevalent, and is the second leading cause of death to
parasitic disease.
This resource will outline the disease biology, epidemiology and
clinical principles of amoebiasis.
Introduction Disease biology Epidemiology Clinical Summary
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Learning Outcomes
The learning outcomes for this moudule are:
• Understand the biology, life cycle and mode of transmission of the amoebiasis
causative organism, Entamoeba histolytica.
• Understand the pathological processes that lead to disease in amoebiasis
• Know the distribution of amoebiasis worldwide, and which geographical,
cultural and economic factors can pre-dispose to the disease
• Know how the disease presents according to the infected organ system.
• Be able to outline the treatment and management of symtomatic and
asymtomatic patients.
• Outline the key features of the developing gal-lectin vaccine.
Introduction Disease biology Epidemiology Clinical Summary
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How to use this module
The module is split into five main sections: introduction, disease biology,
epidemiology, clinical and summary. The information required to complete the
learning outcomes are contained within the disease biology, epidemiology and
clinical sections. At the end of each of these sections there will be a self
assessment section. You will require a pen and paper to write down your answers.
How to navigate
Navigate through the module using the
blue arrows to go back and forth. You may
skip straight to, or back to a section by
clicking the tabs at the top of screen.
Additionally, you may skip through the
sub-sections by clicking on the tabs at
the side of the screen.
Introduction Disease biology Epidemiology Clinical Summary
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• The causitive orgainism is parasitic protazoan, called Entamoeba
histolytica.
•What was once thought to be a single entity, is now recognised as
two morphologically identical but genetically distinct forms; E.
histolytica (pathogen) and E. dispar (commensal).
•This has affected our understanding of amoeba distribution. Many
suspected cases of E. histolytica carrier, may simply have been E.
dispar colonisation
• The WHO recommendes that E. histolytica colonisation should be
treated, however, treatment is unnecessary for E. dispar
colonisation
Causative Organism
Pathogenesis 1
Life Cycle and
transmission 1
Causative
Organism
Life Cycle and
transmission 2
Self Assessment
Pathogenesis 2
E. Histolytica
Introduction Disease biology Epidemiology Clinical Summary
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• Entammoeba histolytica has a biphasic life cycle, existing in two
forms; as an infectious cyst and an amoeboid trophozoite
Life cycle and transmission 1
Mouth - Cyst ingested
Invades gut mucosa – cyst formation
Cyst
Passed in stool Excyst to trophozoite
Trophozoite
Amoebic disease
Introduction Disease biology Epidemiology Clinical Summary
Pathogenesis 1
Life Cycle and
transmission 1
Causative
Organism
Life Cycle and
transmission 2
Self Assessment
Pathogenesis 2
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• Cysts (10-15μm) are ingested via contaminated food or water. A
refractile wall containing chitin, allows the cyst to survive stomach
acid.
• In the terminal ileum or colon, the parasite excysts and begins the
trophozoite stage.
• Trophozoites (10-50μm) are highly motile and pleomorphic. They
are unable to survive outside the human gut.
• Energy is derived from the ingestion of bacteria and food particles.
No mitochondria are present in trophozoites. Respiration enzymes
are prokaryotic in origin and are anaerobic, converting:
glucose + pyruvate ethanol
•Trophozoites reproduce by binary fission and encyst in the colonic
wall. Cysts are passed in the stool where they become infectious.
• The signal for encystation is thought to be via epithelial
galactose/N-acetylgalactosamine specific lectin (gal-lectin) binding
protein.
Life cycle and transmission 2
Introduction Disease biology Epidemiology Clinical Summary
Pathogenesis 1
Life Cycle and
transmission 1
Causative
Organism
Life Cycle and
transmission 2
Self Assessment
Pathogenesis 2
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• Amoebic trophozoites invade the colon causing colitis. They may also invade the
portal circulation and travel to the liver, causing liver abscess.
Gastrointestinal Pathology
• The spectrum of colitis in amoebiasis ranges from mucosal thickening, to
multiple cyst formation, to diffuse Inflammation / oedema, to necrosis and
perforation of colonic wall.
•Binding of E. histolytica to epithelial cells via gal-lectin. This molecule shows
homologous to human CD59, conferring resistance to complement . A change in
the epithelial permeability is induced, probably via the inter-cellular tight
junctions.
• Cell lysis and apoptosis of mucosa are thought to be mediated by amoebapores,
peptides capable of forming pores in lipid bi-layers.
•Trophozoites invade through to the submucosa causing flask shaped cysts .
• Cysteine proteases released by trophozoites digest extracellular matrix in liver
and colon, and induce interleukin-1 mediated inflammation. Proteases also cleave
IgA and IgG antibodies.
•Neutrophils and macrophages are drawn to invasion sites. E. histolytica can lyse
neutrophils leading to further tissue damage, and contributing towards the
induction of diarrhoea.
•Inflammation is a significant cause of tissue damage, however, innate immunity
may be the main combatant against the disease.
Pathogenesis 1
Introduction Disease biology Epidemiology Clinical Summary
Pathogenesis 1
Life Cycle and
transmission 1
Causative
Organism
Life Cycle and
transmission 2
Self Assessment
Pathogenesis 2
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Pathogenesis 2
Hepatic Pathology
• Trophozoites invading the colonic mucosa may enter the hepatic
circulation and reach the liver
Histological cross section of classical flask
shaped amoebic ulcer in colonic mucosa.
Amoebic colitis with multiple ulcer formation
Amoebic liver abscess
•Well circumscribed abscesses are
formed in the liver containing
liquefied cells surrounded by
inflammatory cells and trophozoites
•Adjacent parenchyma is usually
unaffected
Introduction Disease biology Epidemiology Clinical Summary
Pathogenesis 1
Life Cycle and
transmission 1
Causative
Organism
Life Cycle and
transmission 2
Self Assessment
Pathogenesis 2
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Questions
Reveal
Answers
1) Which of the following organisms is the pathogenic causitive
agent of amoebiasis, and which is a commensal?
• Entamoeba histolytica ………………………………………….
• Entamoeba dispar ……………………………………………….
2) Draw a simple diagram oulining the life cycle of entamoeba
histolytica.
3) Which two organs does E. histolytica primarily invade?
4) What is the name and mechanism of action of the peptide
responsible for cell lysis and apoptosis in the mucosa?
5) What is the name of the enzyme group released by trophozoites
to digest the extra-cellular matrix
Introduction Disease biology Epidemiology Clinical Summary
Pathogenesis 1
Life Cycle and
transmission 1
Causative
Organism
Life Cycle and
transmission 2
Self Assessment
Pathogenesis 2
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Answers
1) Which of the following organisms is the pathogenic causitive agent of amoebiasis,
and which is a commensal?
• Entamoeba histolytica ……………Pathogen…………….
• Entamoeba dispar ……………Commensal……………….
2) Draw a simple diagram oulining the life cycle of entamoeba histolytica.
3) Which two organs does E. histolytica primarily invade?
Colon and liver
4) What is the name and mechanism of action of the peptide responsible for cell lysis
and apoptosis in the mucosa?
Cell lysis and apoptosis of mucosa are thought to be mediated by amoebapores,
These peptides form pores in lipid bi-layers of mucosal cells, leading to cell
leakage resulting in lysis and apoptosis.
5) What is the name of the enzyme group released by trophozoites to digest the extra-
cellular matrix ?
Cysteine proteases
Mouth - Cyst ingested
Invades gut mucosa – cyst formation
Cyst
Passed in stool Excyst to trophozoite
Trophozoite
Amoebic
disease
Introduction Disease biology Epidemiology Clinical Summary
Pathogenesis 1
Life Cycle and
transmission 1
Causative
Organism
Life Cycle and
transmission 2
Self Assessment
Pathogenesis 2
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Susceptibility
• Amoebiasis is found primarily in developing tropical and
subtropical countries where sanitation is poor, leading to a direct
link between faeces and ingestion (see Box-1). Occasionally cases
are reported in non-endemic areas e.g. UK and USA. Usually due to
travel and immigration from endemic areas.
• There are an estimated 40,000-100,000 deaths due to amoebiasis
worldwide each year.
Epidemiology
Box-1. Amoebiasis rates/figures
in endemic regions
-Egypt: accounts for 38% of
patients presenting with acute
diarrhoea in outpatient clinic.
-Mexico:1.3 million cases
reported in 1996.
-Hue, Vietnam: 1500 of a
1million population over 5
years
Self Assessment
Epidemiology
Introduction Disease biology Epidemiology Clinical Summary
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Susceptibility
•Generally considered to affect children and adults, of both sexes
equally. However, some data and anecdotal evidence suggests a
male predominance.
•Amoebic liver abscesses are most common in males, 18-55.
•Susceptibility to liver abscess conferred by HLA-DR3 and
complotype SC01 in the Mexican populations
•Other risk factors include oral and anal sex, and contact with
contaminated enema apparatus.
Susceptibility
Self assessment
Epidemiology
Introduction Disease biology Epidemiology Clinical Summary
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Susceptibility
1) How many deaths are caused by amoebiasis each year?
a) 1000 – 5000 b) 40,000-100,000 c) 500,000-1,000,000
2) Which part of the world is amoebiasis primarily found?
a) Developed countries b) Tropical and subtropical c)Cold climates
3) Does amoebiasis affect males or females more?
4) Apart from poor sanitation, what other risk factor pre-dispose to
amoebiasis infection?
Questions
Self assessment
Epidemiology
Reveal
Answers
Introduction Disease biology Epidemiology Clinical Summary
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Susceptibility
Answer
Self assessment
Epidemiology
1) How many deaths are caused by amoebiasis each year?
a) 1000 – 5000 b) 40,000-100,000 c) 500,000-1,000,000
2) Which part of the world is amoebiasis primarily found?
a) Developed countries b) Tropical and subtropical c)Cold climates
3) Does amoebiasis affect males or females more?
Thought to affect both sexes equally, however, anecdotal
evidence suggests a male predominance.
4) Apart from poor sanitation, what other risk factor pre-dispose to
amoebiasis infection?
Other risk factors include oral and anal sex, and contact with
contaminated enema apparatus.
Introduction Disease biology Epidemiology Clinical Summary
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Some individuals carry E. histolytica asymptomatically. 4 -10% will go on to
develop the disease within a year.
Gastroenterological
• Gradual onset (weeks) of bloody diarrhoea, occasionally with small volumes of
mucoid stool. If blood is not visible, stool is usually ‘haem’ positive due to the
breach of the mucosa.
• Abdominal pain and tenderness.
• Leucocytes and pus may be present in stool. Fever present in <40% of patients.
• Weight loss and anorexia can be present.
•In more severe cases fulminant amoebic colitis develops. Liver involvement is
more common in these cases, along with paralytic ileus, toxic megacolon and
mucosal sloughing. Over 75% of patients with fulminant colitis develop intestinal
perforation.
• Local inflammatory masses, amoebomas, may cause obstructive symptoms.
Hepatic
• More common in men
• Liver abscess pan present in conjunction with bowel symptoms (10% of cases), or
in isolation.
• Sudden onset of upper abdominal pain with fever. Pain may radiate to right
shoulder or be exacerbated by repiratory movements.
• Hepatic tenderness may be present. Jaundice is unusual.
•Complicated liver abscess may develop if abscess ruptures into the peritoneal,
pericardial or pleural cavity. Morbidity and mortality is high.
•Rarely, trophozoites may also invade the respiratory tract, brain and GU tract
Presentation
Diagnosis
Treatment and
Management
Presentation
Vaccine
Development 1
Self Assessment
Vaccine
Development 2
Vaccine
Development 3
Introduction Disease biology Epidemiology Clinical Summary
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• Clinical history is important. In low resource settings this may be
the means of diagnosis. A good travel history is important as disease
may develop years after a visit to an endemic area.
•Demonstration of E. histolytica in stool by microscopy (old), or ELISA
assay for antigen detection. Trophozoites only survive for short
periods of time, therefore, fresh stool samples should be used
•Colonoscopy to confirm colitis and tissue biopsy for amoeba
•Liver abscess; space occupying lesion on CT/USS with positive
amoebic serology
Diagnosis
Introduction Disease biology Epidemiology Clinical Summary
Diagnosis
Treatment and
Management
Presentation
Vaccine
Development 1
Self Assessment
Vaccine
Development 2
Vaccine
Development 3
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• Amoebiasis, in particular with liver involvement, can be fatal if not
treated. Chemotherapy can effectively cure ameobiasis.
• Nitroimidazole (e.g.metronidazole) is used to treat the invasive
pathogens – 800mg t.d.s for 10 days.
• This is followed by a luminal agent (e.g.diloxanide furoate) to
eliminate colonisation – 500mg t.d.s for 10 days. This is also suitable
for asymptomatic individuals.
•Complicated liver abscesses should be drained surgically.
Prevention
•Boiling water for at least ten minutes kills amoebic cysts effectively.
Chlorine and iodine tablets are not thought to be 100% effective.
Treatment and Management
Introduction Disease biology Epidemiology Clinical Summary
Diagnosis
Treatment and
Management
Presentation
Vaccine
Development 1
Self Assessment
Vaccine
Development 2
Vaccine
Development 3
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Amoebiasis incidence could be vastly reduced with simple
sanitation and hygiene measures. However, given the current
political and economic climate, this seems unlikely in the near
future. Furthermore, with developing drug resistance in E. histolytica,
vaccine development could be effective.
Why vaccinate?
• Could prevent development of amoebic disease and associated
sequelae.
• Humans only host for E. histolytica, therefore eradication vaccine
would eliminate E. histolytica from the carrier pool.
Which target?
•A number of potential targets have been identified including
cysteine proteases, LPGs and peroxiredoxins. The two most
promising antigens identified are Serine-Rich E. histolytica Protein
(SREHP) and Galactose/N-acetylgalactosamine lectin (Gal-lectin).
Here the potential Gal-lectin vaccine will be described
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Gal – lectin and the immune response
•Gal-lectin is a 260kDa complex protein which consists of disulphide linked light (35
kDa) and heavy subunits (170kDa). The heavy chain is cysteine rich and is thought to be a
target for immune responses, inducing a Th1 cytokine cell mediated immune response
•Macrophages induced by cytokines interferon(INF)-γ have amoebocytic activity, as do
T-cells exposed to INF-γ exposed or TNF.
•Trophozoite killing by macrophages is done via nitric oxide (NO). Gal-lectin can directly
activate macrophages to release NO and induce mRNA transcription of Th1 cytokines,
thereby enhancing the cell mediated immune response.
•Monoclonal antibodies (MAbs), antiserum and IgA secreted from the gut mucosa
against the Gal-Lectin antigen, have the ability to inhibit E. histolytica adherence to
colonic mucosa in vitro.
Vaccine Development 2
IgA, MAb, antiserum
Th1 cell
Macrophage
Key
Activate
Attack
Inhibit
Mucosa
epithelial cell
Gal-lectin
Trophozoite
NO
Cytokines
e.g INF-γ
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Both Gal-lectin classical and DNA based vaccines have been tested in murine
models.
Gal-lectin DNA vaccine
• DNA of heavy gal-lec subunit used as vaccine (see Fig-5)[4]
Induced Th1 mediated anti-body specific response greater than control (nothing),
however response was small. Vaccine moderately inhibited trophozoite adherence
in vitro via anti-body action.
Vaccine Development 3
Gal-lectin classical vaccine
Purified (lectin) and recombinant gal-
letin (LecA) have been trialled, showing
good efficacy in preventing E.
histolytica pathogenesis.
Immunisation were intra-nasal and
intra-peritoneal in order to stimulate
the gastrointestinal immunity.
Protection conferred from purified and
recombinant vaccines
Protection%
Muscle cells take up
and incorporate gal-
lec sequence in DNA
Transfected
into plasmid
Plasmid injected
intra-muscularly
Gene coding for
portion of heavy
gal-lec subunit
isolated
Protein expressed
and immune
response induced
170 35
Production of DNA gal-lectin DNA vaccine in murine model.
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Questions
Reveal
Answer
1) What are the symptoms of gastrointestinal amoebiasis?
2) What are the symptoms of hepatic amoebiasis?
3) Why is a good travel history important in diagnosis of
amoebiasis?
4) What investigations can be performed to confirm a diagnosis?
5) Name two drugs and dosage regimes that can be used to treat
amoebiasis.
6) Is the following statement true or false?
“chlorine and iodine can be used to decontaminate water of
E.histolytica with 100% effectiveness”
7) Does Gal-lectin induce a Th1 or Th2 cell mediated immune
response?
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Answers
1) What are the symptoms of gastrointestinal amoebiasis?
Gradual onset (weeks) of bloody diarrhoea, abdominal pain and tenderness, fever present in
<40% of patients, weight loss and anorexia, amoebomas, may cause obstructive symptoms.
2) What are the symptoms of hepatic amoebiasis?
Sudden onset of upper abdominal pain with fever. Pain may radiate to right shoulder or be
exacerbated by repiratory movements.
Hepatic tenderness may be present. Jaundice is unusual
3) Why is a good travel history important in diagnosis of amoebiasis?
A good travel history is vital to ascertain whether a patient has visited an endemic area. The
disease may develop over a year after travel.
4) What investigations can be performed to confirm a diagnosis?
Demonstration of E. histolytica in stool by microscopy (old), or ELISA assay for antigen detection.
Colonoscopy may be performed to check for colitis and biopsy. Check for liver abscess
with USS or CT.
5) Name two drugs and dosage regimes that can be used to treat amoebiasis.
Nitroimidazole (e.g.metronidazole)– 800mg t.d.s for 10 days. This is followed by a luminal agent
(e.g.diloxanide furoate) 500mg t.d.s for 10 days.
6) Is the following statement true or false?
“chlorine and iodine can be used to decontaminate water of E.histolytica with 100%
effectiveness”
Boiling is the most effective methos for water decontamination
7) Does Gal-lectin induce a Th1 or Th2 cell mediated immune response?
Th1 cell mediated response
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References
Summary
•Amoebiasis is a major global cause of mortality and morbidity,
due to dysentery. The causative organism, E. histolytica.
•E. histolytica has a biphasic life cycle and exists as an infective
cyst and pathological trophozoite.
•The disease is spread via contaminated food and water, usually
due to poor sanitation.
•The disease is found in tropical and sub-tropical parts of the
world.
•Every year, 40,000-100,000 people die from amoebiasis
•Certain genetic traits pre-dispose to certain pathologies.
•Patients usually present with abdominal pain, bloody stools and
fever. Hepatic symptoms are more acute with upper abdominal
pain and radiation to the right shoulder.
•Treatment is with Nitroimidazole (e.g.metronidazole) and a
luminal agent. Spread can be prevented by boiling water.
•A potential gal-lectin vaccine is currently in development. Good
results have been yielded with native gal-lectin vaccines, and
moderate results with a DNA based vaccine. Immunity appears to
be mainly via a Th1 cell medicated response and secretory IgA
Summary
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References
Summary •Gaucher D., Chadee K. (2003). Prospect for an Entamoeba histolytica
Gal-lectin-based vaccine. Parasite Immunology. 25, 55–58 (review)
•Gaucher D., Chadee K. (2002). Construction and immunogenicity of a
codon-optimized Entamoeba histolytica Gal-lectin-based DNA
vaccine. Vaccine. 20, 3244-3253
•Houpt E., Barroso L., Lockhart L., Wright R., Cramer C., Lyerly D., Petri
W.A. (2003) Prevention of intestinal amebiasis by vaccination with
the Entamoeba histolytica Gal/GalNac lectin. Vaccine. 22, 611–617
•Kelly P, Farthing M (2005) Protozoal gastrointestinal infections
Medicine 33: 4 , 81-83.
•Stanley S.L. (2003) Amoebiasis. The lancet. 361,1025-1034 (review)
References and further reading
Introduction Disease biology Epidemiology Clinical Summary