• Ascaris is a genus of parasitic nematode worms known as the "giant intestinal roundworms". • One species, A. suum, typically infects pigs, • while another, A. lumbricoides, affects human populations, typically in sub-tropical and tropical areas with poor sanitation.
• A. lumbricoides is the largest intestinal roundworm and is the most common helminth infection of humans worldwide, an infection known as ascariasis.
TRANSMISSION Ascariasis is not spread directly from one person to another. By the FAECAL-ORAL route, i.e., by ingestion of infective eggs with food or drink. Foods that are eaten raw such as salads and vegetables readily convey the infection, and so is polluted water.
• There is increasing evidence that dust may play an important role in the dissemination of ascaris in arid areas.
Pre-patency:2 monthsPneumonitis:4 – 16 days afterinfection,short duration(~3 wks)
Löeffler Syndrome (Pneumonitis) Transverse sections of Ascaris larvae in pulmonary alveoli
Symptoms Cont.2. Symptoms associated with adult parasite in the intestine• Usually asymptomatic• Abdominal discomfort, nausea in mild cases• Malnutrition• Sometimes fatality may occur when mass of worm blocks the intestine
Ascaris(roundworm):The onlynematode evercoughed orvomited up
Diagnosis• Stool microscopy :• Eosinophilia: eosinophilia can be found, particularly during larval migration through the lungs• Ultrasound: ultrasound exams can help to diagnose hepatobiliary or pancreatic ascariasis. • Endoscopic Retrograde Cholangiopancreatography (ERCP) : A duodenoscope with a snare to extract the worm out of the patient
Prevention • Proper washing of the vegetables. • Health education. • Washing hands before meals. • Mass treatment for the patients. • Sanitary disposal for the feces. • Avoid uses of feces as manures.
The Human HookwormsNecator americanusAncylostoma duodenale
Morphology1. Adults: They look like an odd piece thread and are about 1cm.2. They are white or light pinkish when living. ♀is slightly larger than♂.
2. Eggs: oval in shape, shell is thin and colorless. Content is 2-8cells.
Acylostoma duodenale & Necatoramericanus -- human hookworms • Small nematodes (1-1.5 cm) • Head is slightly bend (hook) and the ‘mouth’ carries characteristic teeth (Ancylostoma) or plates (Necator,
• note the presence of four "teeth," two on each side.
Necator americanus• Note the presence of two cutting "teeth“.
Pathogenesis and Clinical Manifestations • Skin penetration and associated secondary bacterial infection can result in “ground itch” • Pulmonary phase is usually asymptomatic • Intestinal phase: worms attach to the mucosa and feed on blood. Worms continuously move to new places exacerbating bleeding
Hookworms • The main concern with hook worm disease is blood loss • 0.03 ml to 0.26 ml (A.d) per worm, up to 200 ml per day in heavy infections • Chronic heavy infection results in anemia and iron deficiency
Transmission• Amoebiasis is usually transmitted by the fecal-oral route,• but it can also be transmitted indirectly through contact with dirty hands or objects as well as by anal-oral contact.
Pathology and Clinical Manifestation• Pinpoint lesion on mucous membrane• Flask-shaped ulcers
A. Intestinal amoebiasis• a. dysentery: dysenteric stools (pus and blood dysentery: without feces). fever, dehydration, and electrolyte abnormalities. • b. non-dysenteric colitis• c. appendicitis• d. amoeboma: may become the leading point of an intussusception or may cause intestinal obstruction.
Histopathology of a typical flask-shaped ulcer of intestinal amebiasis
B. Extra-intestinal amoebiasis• a. Hepatic • (1) acute non-suppurative• (2) liver abscess:• b. Pulmonary
Treatment and Prevention• Treatment:• Diodoquin-carriers• Metronidazole-dysentery, liver abscess
Preventing Amoebiasis• Drink only bottled or boiled (for 1 minute) water.• Fountain drinks and any drinks with ice cubes are not safe. Water can be made safe by filtering it through an "absolute 1 micron or less" filter and dissolving iodine tablets in the filtered water. • Avoid milk, cheese, or dairy products that may not have been pasteurized.
Food safety• Thoroughly cook all raw foods. • * Thoroughly wash raw vegetables and fruits before eating. • * Reheat food until the internal temperature of the food reaches at least 167º Fahrenheit.• Wash your hands before preparing food, before eating, after going to the toilet or changing diapers,
Epidemiology DistributionWorldwide distribution, endemic and epidemic.Traveler diarrheaPatients with variable immunodeficiency areincreasingly susceptible to infection with Giardia.
Epidemiology Transmission sourcePersons whose feces containing cystsMonkeys and pigs can also be infected, the infectedpig may be a source of human infection. Transmission drinking contaminated waterInfected by eating contaminated food
DiagnosisPathogenic examination (1) Fecal examination (2) Duodenal fluid or bile examination (3) Intestinal examination by gelatin capsule
Cysts have strong resistanceCysts can keep alive 10 or more days in feces Cysts are often waterborne, either by taking inadequately treated municipal water supplies of contaminated river or stream Giardiasis is more common in travelers, Immunodeficiency persons
Prevention and controlTreat the patients and cyst carriers Metronidazole TinidazoleTreatment of the drinking water Suspect water should be boiled or adequately filtered to remove the infective cysts before drinking.
fecal-oral Animal to human Contamination of water supplies (result of waste runoff) *WATER-BORNE MOST COMMON* COMMON
SYMPTOMS• Immunocompetent • Immunocompromised – Mild self-limiting – 50 or more stools per enterocolitis (watery day bloodless diarrhea, – Dehydration (fatigue, abdominal pain, nausea, abdominal cramping, vomiting, and fever) and nausea) – Common in AIDS patients
LAB DIAGNOSIS Microscopic exam Acid fast stain of stool sample Endoscopic biopsy of small intestine
• Infectious agents are the OOCYSTS• In immunocompromised patients ID50 is about 10 to 30 oocysts
TREATMENT• Immunocompetent • Immunocompromised – Self-limiting – Cocktail therapy -used to treat symptoms but – Usually symptoms NOT THE DISEASE subside within 10 – Drugs include: letrazuril, days azithromycin, paramycin, and hyperimmune bovine colostral immunoglobulin *The only immunity is previous exposure and extent of this immunity is not known.*
WATER PREVENTION • Ozone • UV light • boiling • “Chlorine not effective against crypto!!”
CONTROL OF PROTOZOA INDRINKING WATER Multiple barrier approach: Filtration Chemical inactivation- ozone, combination of disinfectants Medium-pressure ultraviolet light (UV) Monitoring: Presence of protozoa in raw water