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Water-borne diseases, Water-washed diseases, Water-based diseases, Water-related diseases.

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Public health

  2. 2. 9.1. Disease and Water• What is pathogenic? – refers to the ability of an organism to cause disease. This direct and indirect action of pathogens allows water-related diseases. Water-borne Water-washed Water-based Water-related diseases diseases diseases diseases
  3. 3. I- Water-borne diseases• Water-borne diseases are any ilness cause by drinking water contaminated by human or animal faeces, which contain pathogenic microorganisms.• The classical water-borne diseases are mainly low-infective dose infections, such as cholera, typhoid, and leptospirosis.• All the remaining diseases are high-infective dose infections and include infectious hepatitis and bacillary dysentery.
  4. 4. I- Water-borne diseasesClinical Syndromes Type I • Noninflammatory (enterotoxin, etc.) • Proximal small bowel • Watery diarrhea Giardia lamblia • Examples: – Rotavirus – Vibrio cholerae – Giardia lamblia – Cryptosporidium parvum – Cyclopsora cayetanensis Cholera toxin
  5. 5. I- Water-borne diseases Type IIClinical Syndromes • Inflammatory (invasive, cytotoxin) • Colon • Dysentery (bloody diarrhea) • Examples: – Salmonella enteriditis – Clostridium difficile – Campylobacter pylori Enatmeba histolytica – Enatmeba histolytica
  6. 6. I- Water-borne diseasesClinical Syndromes Type III • Penetrating • Distal small bowel • Examples: – Salmonella typhi – Yersinia enterococolithica Salmonella typhi
  7. 7. II- Water-washed diseases• Caused by a lack of personal hygiene because of water scarcity.• These are diseases of mainly tropical areas and include infections of the intestinal tract, the skin, and the eyes.• The intestinal infections are all faecal in origin and include all the water-borne diseases that are contracted because of poor personal hygiene.
  8. 8. II- Water-washed diseases • The germs in the faeces can cause the diseases by evenTransmission slight contact and transfer. • This contamination may occur due to floodwaters, water runoff from landfills, septic fields, and sewer pipes. Faecal-oral routes of diseases transmission.
  9. 9. II- Water-washed diseasesTransmission • The only way to break the continued transmission is to improve the people’s hygienic behaviour and to provide them with certain basic needs: – drinking water, – washing and bathing facilities and – sanitation.
  10. 10. II- Water-washed diseases• Most of the intestinal infections are diarrhoeal diseases responsible for the high mortality rates among infants in the developing world. • The infections of the skin and mucous membranes are non-faecal in origin and include bacterial skin sepsis, scabies, and cutaneous fungal infections (such as ringworm). • Diseases spread by fleas, ticks, and lice are also included in this category, such as epidemic typhus, rickettsial typhus, and louse-borne fever.
  11. 11. III- Water-based diseases• Water-based diseases are caused by pathogens that have a complex life-cycle and which require an intermediate aquatic host.• All these diseases are caused by parasitic worms with the severity of the infection depending on the number of worms infecting the host.
  12. 12. III- Water-based diseases• The two commonest water-based diseases are Schistosomias is carried by the trematode Schistosoma spp. and Guine a worm which is the nematode Dracunculus medimensis.• Schistosoma worms use aquatic snails as intermediate hosts and are estimated as infecting as many as 200 million people, and the Guine a worm uses the small crustacean Cyclops spp. as its intermediate host. Guine worm
  13. 13. III- Water-based diseases Human Schistosomiasis
  14. 14. IV- Water-related diseases• Caused by pathogens carried by insects that act as mechanical vectors and which live near water.• All these diseases are very severe and control of the insect vectors is extremely difficult.• The most important water-related diseases include two viral diseases, – yellow fever, transmitted by the mosquito Aedes spp. – dengue, which is carried by the mosquito Aedes aegypti which breeds in water.
  15. 15. 9.2. Water-borne diseases• Industrial waste waters rarely contain pathogens, whereas pathogens are common in food processing wastes.• The pathogens found are directly related to the original plant or animal materials being processed.• In sewage, it is the diseases excreted by man via faeces and urine that are of primary importance to public health.
  16. 16. 9.2. Water-borne diseases• Pathogens in sewage are able to infect man and animals by oral ingestion, via the skin or by respiratory routes.• The commonest infection route for pathogens is oral ingestion, which generally causes gastro-enteric disorders.
  17. 17. Water-borne diseases -9.2.2. Bacteria -Salmonellosis• Gram-negative, rod-shaped and facultative anaerobe in the family Enterobacteriaceae.• Primary sources of salmonellae are intestinal tracts of animals (domestic and wild) and humans; shed in feces. – Feces can contaminate soil and water (irrigation and processing) – Salmonellae can survive in some soils for months to years; in water for weeks to months
  18. 18. Water-borne diseases - 9.2.2. Bacteria -Salmonellosis• Some serotypes are largely specific to a single host, and these include the typhoid organism – S. typhi, specific to man; – S. dublin, specific for cattle; – S. abortus-ovis, specific for sheep; and – S. cholerae-suis, specific for pigs.• Other serotypes are not host-specific, for example, – S. typhimurium which can infect a wide range of animals, including man.
  19. 19. Water-borne diseases - 9.2.2. Bacteria -Salmonellosis• The pathogen produces an endotoxin causing the typical symptoms of salmonellosis such as – acute gastro-enteritis with diarrhoea, and is often associated with – abdominal cramps, – fever, – nausea, – vomiting, – headache, and – in severe cases, even collapse and possible death.• In pregnant animals, abortion may occur.
  20. 20. Water-borne diseases - 9.2.2. Bacteria -Salmonellosis
  21. 21. Water-borne diseases - 9.2.2. Bacteria -Salmonellosis• Incubation period: 1-3d• Signs and symptoms: diarrhea, fever, cramps, vomiting, s. typhi and paratyphi cause chills, myalgia, headache, with rare diarrhea• Duration: 4-7d• Food Source: eggs, poultry, unpasteurized milk or juice, raw fruits and vegetables, street venders, fecal water contamination• Lab testing: stool cultures• Treatment: ciprofloxacin or TMP-SMX. Antibiotics for severe cases only Necessitates typhoid immunization for travelers
  22. 22. Water-borne diseases - 9.2.2. Bacteria -Campylobacter• Gram-negative• spirally shaped• flagellated• oxidase-positive,• reduce nitrates• unable to produce acid in the presence of carbohydrates• isolated from both fresh and estuarine waters• causes acute gastro-enteritis (i.e. fever, nausea, adominal pains, diarrhoea and vomiting)
  23. 23. Water-borne diseases - 9.2.2. Bacteria -Campylobacter• Water is either contaminated directly by sewage which is rich in Campylobacter or indirectly from animal faeces.• Household pets, farm animals and birds are all known to be carriers of the disease.
  24. 24. Water-borne diseases - 9.2.2. Bacteria -Campylobacter• Incubation period: 2-5d• Signs and symptoms: bloody or watery diarrhea, cramps, fever• Duration: 2-10d• Food Source : Poultry, milk, water• Lab testing: special stool culture• Treatment: erythromycin or ciprofloxacin-antibiotic for severe cases only
  25. 25. Water-borne diseases - 9.2.2. Bacteria -Shigellosis• Gram-negative• non-motile• rods shaped• oxidase-negative• Shigella causes bacterial dysentery or shigellosis• Shigellosis is a problem of both developed and developing countries with the Eastern Mediterranean countries considered as an endemic region for the disease.
  26. 26. Water-borne diseases - 9.2.2. Bacteria -Shigellosis• When the disease is present as an epidemic, it appears to be spread mainly by person to person contact, especially between children, shigellosis being a typical institutional disease occurring in over-crowded conditions.• It may also be carried asymptomatically in the intestinal tract.
  27. 27. Water-borne diseases - 9.2.2. Bacteria -Leptospirosis• A potentially serious illness that can affect many parts of the body• Caused by Leptospira interrogans, a corkscrew-shaped bacterium (spirochete)• Leptospirosis-causing bacteria are common worldwide, especially in tropical countries with heavy rainfall.
  28. 28. Water-borne diseases - 9.2.2. Bacteria -Leptospirosis Infected rodents and other wild and domestic animals pass the bacteria in their urine.The bacteria can live for a long time in fresh water, dampsoil, vegetation, and mud.Flooding after heavy rainfall helpsspread the bacteria in theenvironment.
  29. 29. Water-borne diseases - 9.2.2. Bacteria -Leptospirosis• People get leptospirosis by contact with fresh water, damp soil, or vegetation contaminated by the urine of infected animals.• People who canoe, raft, wade, or swim in contaminated lakes, rivers, and streams can get leptospirosis.• Symptoms include fever, headache, chills, nausea and vomiting, eye inflammation, and muscle aches.
  30. 30. Water-borne diseases - 9.2.2. Bacteria -Leptospirosis• In more severe cases, the illness can result in liver damage and jaundice (yellowing of the skin and whites of the eyes), kidney failure, and internal bleeding.• People who are seriously ill with leptospirosis often need to be hospitalized.
  31. 31. Water-borne diseases - 9.2.2. Bacteria -Leptospirosis• Symptoms usually begin about 10 days after infection.• Diagnosed by a special blood test.• Leptospirosis is treatable with antibiotics.
  32. 32. Water-borne diseases - 9.2.2. Bacteria -Escherichia coli• Gram-negative,• non-sporulating• rod-shaped bacterium• either nonmotile or motile• commonly found in the lower intestine of warm-blooded organisms (endotherms).• A number of strains of E.coli are pathogenic and cause characteristic gastro-enteritis.
  33. 33. Water-borne diseases - 9.2.2. Bacteria -Escherichia coli• Pathogenic E.coli are classified into four main groups based on – virulence properties, – clinical syndrome, – epidemiology, – O:H serogrouping.• causes of many common bacterial infections, including cholecystitis, bacteremia, cholangitis, urin ary tract infection (UTI), and travelers diarrhea, and other clinical infections such as neonatal meningitis and pneumonia..
  34. 34. Water-borne diseases - 9.2.2. Bacteria -Escherichia coli• Most E. coli infections come from: – Eating undercooked ground beef (the inside is pink) – Drinking contaminated (impure) water – Drinking unpasteurized (raw) milk – Working with cattle
  35. 35. Water-borne diseases - 9.2.2. Bacteria -Escherichia coli• Incubation period: 1-3d• Signs and symptoms: watery diarrhea, vomiting, cramps• Duration: 3-10d• Food Source: fecal contamination of food• Lab testing: specific stool culture• Treatment: ciprofloxacin-antibiotic for severe cases only or TMP-SMX
  36. 36. Water-borne diseases - 9.2.2. Bacteria -Cholera• Cholera is an infection of the small intestine that causes a large amount of watery diarrhea.• Cholera is caused by the bacterium Vibrio cholerae.• The bacteria releases a toxin that causes increased release of water in the intestines, which produces severe diarrhea.
  37. 37. Water-borne diseases - 9.2.2. Bacteria -Cholera• Cholera occurs in places with poor sanitation, crowding, war, and famine. Common locations for cholera include: – Africa – Asia – India – Mexico – South and Central America – The Mediterranean
  38. 38. Water-borne diseases - 9.2.2. Bacteria -Cholera
  39. 39. Water-borne diseases - 9.2.2. Bacteria -Cholera• Upto106–107 organisms are required to cause the illness, so cholera is not normally spread by person-to-person contact.• It is readily transmitted by drinking contaminated water either by eating food handled by a carrier or which has been washed with contaminated water.
  40. 40. Water-borne diseases - 9.2.2. Bacteria -Cholera• An infected person or symptom less carrier of the disease excretes up to 1013 bacteria daily, enough to theoretically infect 107 people!• It is an intestinal disease with characteristic symptoms, that is sudden diarrhoea with copious watery faeces, vomiting, suppression of urine, rapid dehydration, lowered temperature and blood pressure, and complete collapse.
  41. 41. Water-borne diseases - 9.2.2. Bacteria -Cholera• Without therapy the disease has a 60% mortality rate, the patient dying within a few hours of first showing the symptoms, although with suitable treatment the mortality rate can be reduced to less than one percent.
  42. 42. Water-borne diseases - 9.2.2. Bacteria -Cholera• Incubation period: 24-72h• Signs and symptoms: severe watery diarrhea and vomiting• Duration: 3-7d death from dehydration• Food Source: contaminated water, fish, shellfish, street vendors• Lab testing: specific stool cultures• Treatment: ciprofloxacin in adults, TMP-SMX in children
  43. 43. Water-borne diseases - 9.2.2. Bacteria -Tularemia• Tularemia is a serious infectious disease caused by the bacterium Francisella tularensis.• A Gram-negative, nonmotile coccobacillus, the bacterium has several subspecies with varying degrees of virulence.• F. tularensis can infect many animals, especially small rodents, rabbits and hares.
  44. 44. Water-borne diseases - 9.2.2. Bacteria -Tularemia• Tularemia infections occur throughout the Northern Hemisphere.• There are two types of the bacterium, both of which can infect humans. A tularemia lesion on the dorsal skin Type A Type B of right hand. tularemia tularemia
  45. 45. Water-borne diseases - 9.2.2. Bacteria -Tularemia• Type A infects animals and ticks in North America. Infection is often sporadic and severe and can be fatal in humans. Type A infections have not been described as occurring naturally outside North America.• Type B occurs in animals throughout the northern hemisphere including North America, causes milder symptoms than type A, and does not cause fatal infections. Large outbreaks have occurred.
  46. 46. Water-borne diseases - 9.2.2. Bacteria -Tularemia• Person to person transmission of F. tularensis has never been documented. Infection may occur by: – Bite of an insect, e.g. tick or mosquito, which has fed on an infected – animal. Direct contact with the tissues/secretions of infected animals. – Inhaling or ingesting bacteria. – Contact with or consumption of contaminated food or water.
  47. 47. Water-borne diseases - 9.2.2. Bacteria -Tularemia• Symptoms: – Chills, Fever, Headache, Joint stiffness, Muscle pains, Possible conjunctivitis, Red spot on the skin, enlarging to a sore (ulcer), Shortness of breath, Sweating, Weight loss• Exams and Tests: – Blood culture for tularemia, Blood test measuring the bodys immune response to the infection (serology for tularemia), Chest x-ray, Polymerase chain reaction (PCR) test of a sample from an ulcer• Treatment: – Streptomycin, tetracycline, gentamycin..
  48. 48. Water-borne diseases - 9.2.2. Bacteria -Mycobacteria• Tuberculosis or TB is a common and often deadly infectious diease caused by mycobacteria, usually Mycobacterium tuberculosis in humans.• Tuberculosis usually attacks the lungs but can also affect other parts of the body.• The classic symtoms are a chronic cough with blood-tinged sputum, fever, night sweats, and weight loss.
  49. 49. Water-borne diseases - 9.2.2. Bacteria -Mycobacteria• The primary cause of TB, Mycobacterium tuberculosis, is a small aerobic non-motile bacillus.• The M. tuberculosis complex includes four other TB causing mycobacteria: – M. bovis, M. africanum, M. canetti and M. microti.• M. africanum is not widespread, but in parts of Africa it is a significant cause of tuberculosis.
  50. 50. Water-borne diseases - 9.2.2. Bacteria -Mycobacteria• M.tuberculosis is frequently isolated in wastewater from hospitals and meat-processing plants.• Like Leptospira, the bacilli are able to survive for several weeks at low temperatures in water contaminated with organic matter.• Clearly, drinking contaminated water must be a source of infection.
  51. 51. Water-borne diseases - 9.2.2. Bacteria -Mycobacteria Lepromatous Leprosy (Early/Late Stages)
  52. 52. Water-borne diseases - 9.2.2. Bacteria -Brucellosis• Caused by various Brucella species, which mainly infect cattle, swine, goats, sheep and dogs.• Humans generally acquire the disease through direct contact with infected animals, by eating or drinking contaminated animal products, or by inhaling airborne agents.
  53. 53. Water-borne diseases - 9.2.2. Bacteria -Brucellosis• The majority of cases are caused by ingesting unpasteurized milk or cheese from infected goats or sheep.• Person-to-person transmission is rare.• The disease causes flu-like symptoms, including fever, weakness, malaise and weight loss.
  54. 54. Water-borne diseases - 9.2.2. Bacteria -Brucellosis Swollen “knee” joint of caribou due to brucellosis.
  55. 55. Water-borne diseases - 9.2.2. Bacteria -Brucellosis• Incubation period: 7-21d• Signs and symptoms: fever, chills, headache, myalgias, arthralgias, bloody diarrhea• Duration : weeks• Food Source: raw milk, goat cheese, meats• Lab testing: blood, serology• Treatment: rifampin and doxycycline
  56. 56. Water-borne diseases - 9.2.2. Bacteria -Aeromonads• Ubiquitous oxidase-positive,• glucose-fermenting,• motile,• not curved gram-negative rods• widely distributed in fresh and salt water environments Aeromonas hydrophila adhering to• Isolated from produce and human epithelial cells. meat sources
  57. 57. Water-borne diseases - 9.2.2. Bacteria -Aeromonads• Aeromonas gastroenteritis usually results from consumption of contaminated seafood, especially raw oysters or clams;• illness usually self-limiting, except in very young and old populations.• Wound infections usually from Aeromonas hydrophilia resulting from traumatic water-related wound. Human leg infected with Aeromonas hydrophila
  58. 58. Water-borne diseases - 9.2.2. Bacteria -Helicobacter pylori• Gram-negative• Spiral-shaped• Flagellated• Microaerophilic• Colonize the gastric epithelium of humans.
  59. 59. Water-borne diseases - 9.2.2. Bacteria -Helicobacter pylori• causing – peptic ulcers, – chronic type B gastro-enteritis, – and as a risk factor for gastric cancer – gastric lymphoma – coronary heart disease
  60. 60. Water-borne diseases - 9.2.2. Bacteria -Helicobacter pylori• isolated in a wide range of natural waters as well as drinking water and wastewater using PCR.• can be transferred via drinking water and food.• its natural niche is the human stomach,• needs to survive in the natural environment in order to be a life-long infection.• nothing is known of its survival or ecology in the natural environment
  61. 61. Water-borne diseases -9.2.3. Viruses -• There are over 140 distinct known types of human pathogenic viruses.• Of most concern are those which cause gastrointestinal illness known as the enteric viruses which includes ; » enteroviruses, » rotaviruses, » astroviruses, » calciviruses, » hepatitis A virus, » Norwalk virus and » other ‘small round’ viruses
  62. 62. Water-borne diseases - 9.2.3. Viruses - Common waterborne enteric viruses and the disease they cause (Bitton 1994)
  63. 63. Water-borne diseases - 9.2.3. Viruses -• Human viruses present in sewage are almost entirely derived from faecal matter.• Viral contamination arises when sewage containing pathogenic viruses contaminates surface and ground waters which are subsequently used as sources of drinking waters (West 1991).
  64. 64. Water-borne diseases - 9.2.3. Viruses -• Large outbreaks of viral disease occur when massive sewage contamination takes place overwhelming existing water treatment mechanisms.• Infectious hepatitis, entroviruses, reovirus and adenovirus are all thought to be transmitted via water.
  65. 65. Water-borne diseases - 9.2.3. Viruses -• Of most concern in Europe is viral hepatitis.• There are three subgroups: – Hepatitis A Virus (HAV) which is transmitted by water; – Hepatitis B which is spread by infected blood or sexual contact is endemic in certain countries such as Greece – Hepatitis C which is a non- A or B type hepatitis virus
  66. 66. Water-borne diseases - 9.2.3. Viruses -• Hepatitis A is a 27 nm RNA entrovirus that is spread by faecal contamination of food, drinking water, and areas that are used for bathing and swimming (Jehl- Pietri 1992).• There is no treatment for hepatitis A, with the only effective protection good personal hygiene, and the proper protection and treatment of drinking water.
  67. 67. Water-borne diseases - 9.2.3. Viruses -• Hepatitis A virus accounts for 87% of all viral water borne disease outbreaks in the USA (Craun 1986).• In June 1979, a large water borne outbreak of gastroenteritis and hepatitis occurred in Georgetown, Texas, affecting approximately 79% of individuals supplied by the contaminated water following a period of heavy rain fall that washed sewage into the ground water supply.
  68. 68. Water-borne diseases - 9.2.3. Viruses -• The best documented outbreak of water borne viral disease occurred in New Delhi, India in 1955/56, when 35,000 cases of infectious hepatitis were reported following gross contamination of the water supply by sewage (Dennis 1959).• Brugha et al. (1998) reported that those who are regularly exposed to sewage have a significant risk factor for HAV infection and should be vaccinated.
  69. 69. Water-borne diseases - 9.2.3. Viruses -• Warm-blooded animals appear able to carry viruses pathogenic to man.• For example, 10% of beagles have been shown to carry human enteric viruses; therefore, there appears a danger of infection from waters not contaminated by sewage but by other sources of pollution, especially storm water from paved areas.
  70. 70. Water-borne diseases - 9.2.3. Viruses -• Most viruses are able to remain viable for several weeks in water at low temperatures, so long as there is some organic matter present.• Viruses are found in both surface and groundwater sources.• Two viruses which have caused recent outbreaks of illness due to drinking water contamination are Norwalk virus and rotavirus
  71. 71. Water-borne diseases - 9.2.3. Viruses -• Norwalk virus results in severe diarrhoea and vomiting. It is of particular worry to the water industry in that it appears not to be affected by normal chlorination levels.• Also it seems that infection by the virus only gives rise to short-term immunity, while lifelong immunity is conferred by most other enteric viruses.
  72. 72. Water-borne diseases - 9.2.3. Viruses -Examples of waterborne outbreaks due to the Norwalk virus(Bitton 1994). The largest of these outbreaks occurred in Rome, Georgia (USA) in 1980, when contaminated water from a textile factory came into contact with a community water supply.
  73. 73. Water-borne diseases - 9.2.3. Viruses -• Rotavirus is a major contributor to child diarrhoea syndrome.• This causes the death of some six million children in developing countries each year.• Outbreaks do occur occasionally in hospitals, and although associated with child diarrhoea, can be much more serious if contracted by an adult.
  74. 74. Water-borne diseases - 9.2.3. Viruses -• A large outbreak of gastro-enteritis affecting 900 people due to contamination of a water supply by sewage containing rotaviruses was reported in Arizona in 1991.• Other major outbreaks include 11,600 infected in East Germany in 1981–1982 when flood water contaminated wells, and a year later in China when 13,311 were infected with rotavirus due to a contaminated water supply (Williams and Akin 1986).
  75. 75. Angola, Burundi, Cameroo n, the Democratic Republic ofCongo, Djibouti, Ethiopia,Ghana, Madagascar, Mala wi, Niger, Rwanda and Tanzania. Sudan became the first African country to introduce the rotavirus vaccine with GAVI Alliance funding last July -- only two years after the World Health Organization recommended all countries introduce rotavirus vaccines into their immunization programs.
  76. 76. Water-borne diseases - 9.2.3. Viruses -• Astroviruses are another common cause of gastroenteritis in young children, with 75 % of those aged between 5–10 years shown to have the astrovirus antibody in the UK (Kurtz and Lee 1978), with astrovirus is the major infection causing serotype (Lee and Kurtz 1994).• As with bacterial infections, many incidents of viral disease asociated with drinking water have been attributable to untreated or inadequately treated water or to defects within the distribution system (Craun1988). » Gerba and Rose (1990) have produced an excellent review on viruses in source and drinking waters.
  77. 77. Water-borne diseases - 9.2.3. Viruses -• Out breaks of water borne viral disease, other than infectious hepatitis, are difficult to recognize because viruses tend to cause non-apparent or latent infections (Tyler1985).• Each year a large percentage of reported cases of water borne disease are of unknown aetiology (Herwaldt etal. 1992; Galbraith etal. 1987).
  78. 78. Water-borne diseases - 9.2.3. Viruses -• One possible explanation for such defects in the data is that epidemiological methods are not adequate enough to detect low level transmission of viral diseases via water.• This is because a single viral type may produce a wide variety of symptoms which may not be attributable to a single aetiologic agent, also different viruses can produce similar symptoms (Tyler 1985).
  79. 79. Water-borne diseases - 9.2.3. Viruses -• Sewage treatment, virus dilution, natural inactivation, water treatment, and other factors combine to reduce viral numbers to a few survivors in large volumes of water (Metcalf 1978).• In the more developed regions of the world, the possibility of viral transmission of water borne disease depends on the ability of minimum quantities of virus causing infections (APHA 1992).
  80. 80. Water-borne diseases - 9.2.3. Viruses -• Detecting viruses in water through the recovery of infectious virus involves three steps: – (i) Collecting of representative samples. – (ii) Concentrating the viruses in the sample. – (iii) Identifying and estimating quantities of the concentrated virus (APHA 1992).
  81. 81. Water-borne diseases - 9.2.3. Viruses -• Viral numbers are generally so low that their detection is virtually impossible unless they are first concentrated.• Many of the concentration techniques available are based on one of two principles; – either the filter adsorption-elution systems or – ultra filtration systems (Sobsey 1975).
  82. 82. Water-borne diseases - Viruses -
  83. 83. Water-borne diseases - 9.2.3. Viruses -• For many years chlorination was considered to be effective in preventing contamination of water supplies by viruses.• This conclusion was drawn from the results of epidemiological studies, where it has been repeatedly shown that outbreaks due to viral contamination occurred largely in situations where there was in adequate or no chlorination (Galbraith et al. 1987; Herwaldt et al. 1992).
  84. 84. Water-borne diseases - 9.2.3. Viruses -• However, in recent years there has been a noticeable change in this situation.• Enteric viruses have been isolated from drinking waters which have been treated by chlorination or other processes such as ozonation and chemical coagulation.
  85. 85. Water-borne diseases - 9.2.3. Viruses -• Initially the ability to survive chlorination was thought to be due to a lack of contact time with chlorine (Melnick and Gerba 1980).• It is now well established that some enteric viruses are more resistant to chlorination than coliforms (Shaffer et al. 1980).
  86. 86. Water-borne diseases - 9.2.3. Viruses -• Entero viruses have been recovered from waters which are free from indicator organisms.• There has been considerable debate over whether or not there is continual low-level viral contamination of drinking water which subsequently results in sporadic viral infections among consumers (Sellwood and Dadswell 1991).
  87. 87. Water-borne diseases - 9.2.4. Protozoa -• Protozoan pathogens of man are almost exclusively confined to tropical and sub-tropical areas, which is why the increased occurrence of Cryptosporidium and Giardia cysts in temperate areas is causing so much concern..
  88. 88. Water-borne diseases - 9.2.4. Protozoa -Giardiasis• Giardia lamblia is a flagellated protozoan belonging to the class Zomastigophorasida, order Diplomonadonda and family Hexamitidae.• It was first recorded in 1681 by Leeuwenhoek who discovered the organism in his own stools.• It was later named Giardia lamblia after Giard who studied the parasite and Lamb who first described it.
  89. 89. Water-borne diseases - 9.2.4. Protozoa -Giardiasis• For more than a century after its initial discovery, the pathogenic potential of Giardia was not fully appreciated.• Indeed up to the 1960s, it was widely believed to be a commensal parasite of doubtful pathogenicity. Giardia lamblia
  90. 90. Water-borne diseases - 9.2.4. Protozoa -Giardiasis• Giardia lamblia exists in a trophozoite and cyst form. Trophozoites are easily recognised. Their bodies are pear or kite shaped, approximately 9– 21 µm long by 6 µm wide with an anterior sucking disc on the flattened ventral surface. Cysts are ovoid,14–16 µm long and 6–12 µm wide and are quadrinucleate.
  91. 91. GiardiasisGiardia cysts arerelatively resistantto environmentalconditions and arecapable of survivalonce excreted forlong periods,especially in winter.
  92. 92. Water-borne diseases - 9.2.4. Protozoa -Giardiasis• Giardia is one of the most common waterborne parasites in the United States.• Giardia has been blamed for illnesses from both recreational and drinking water.• Giardia exists within every region of the United States and it is also found worldwide.
  93. 93. Water-borne diseases - 9.2.4. Protozoa -Giardiasis• A study of raw water supplies in the USA by Le Chevallier et al. (1991) found that Giardia cysts are present in as many as 81% of raw water supplies largely due to the introduction of sewage effluents and in 17% of finished water supplies (Le Chevallier et al. 1991).• A similar survey in Scotland found that 48% of raw waters and 23% of treated water supplies sampled contained cysts (Gray 1994).
  94. 94. Water-borne diseases - 9.2.4. Protozoa -Giardiasis• Giardiasis is quite contagious. Just one infected human or animal can release millions of Giardia parasites into the environment through fecal matter.• As few as 10 microscopic Giardia parasites in a glass of water can cause a severe case of Giardiasis in the human being who drinks it.• The parasites are often found alive in soil, food, water, and contaminated surfaces.
  95. 95. Water-borne diseases - 9.2.4. Protozoa -Giardiasis• While you can be infected by Giardia by swallowing the parasite, Giardia is not spread through blood contact.• Here are some common ways the Giardia parasite is transmitted: – Swallowing contaminated water while swimming in pools, fountains, hot tubs, lakes, rivers, ponds, streams, springs, and water parks. – Eating uncooked food that has been contaminated with Giardia (i.e. through unsanitary food preparation). – Accidentally picking up Giardia from contaminated surfaces like diapers, bathroom fixtures, or toys
  96. 96. Water-borne diseases - 9.2.4. Protozoa -Giardiasis• The symptoms of giardiasis usually appear about 1 to 2 weeks after infection by the Giardia parasite. The symptoms of giardiasis include: – Diarrhea – Upset stomach – Intestinal gas – Nausea – Stomach cramps – Dehydration and weight loss – Abdominal pain above the navel – Greasy stools
  97. 97. Water-borne diseases - 9.2.4. Protozoa -Giardiasis• To prevent infection, do not drink (or accidently swallow) untreated water from lakes, rivers, streams, springs or shallow wells.• In countries where the water supply may not be safe, untreated drinking water or ice should be avoided.• All raw vegetables or fruits should be washed before eating in water known to be uncontaminated.• Good hygiene, such as hand washing, can help prevent infection and reduce spreading giardiasis to other people.
  98. 98. Water-borne diseases - 9.2.4. Protozoa -Cryptosporidiosis• What is Cryptosporidiosis?• Cryptosporidiosis is a disease caused by an intestinal parasite called Cryptosporidium commonly found in lakes and rivers, especially when the water is contaminated with sewage and animal wastes.
  99. 99. Water-borne diseases - 9.2.4. Protozoa -Cryptosporidiosis• How do you get cryptosporidiosis?• The parasite Cryptosporidium parvum is found in the feces of infected animals and people.• The parasite, which can be present in sewage or runoff from feed lots, can contaminate water sources, and several large waterborne outbreaks have occurred.• Outbreaks also have occurred in child day care centers. In Illinois, 75-100 cases of cryptosporidiosis are reported annually.
  100. 100. Water-borne diseases - 9.2.4. Protozoa -Cryptosporidiosis Persons, dogs and cats become infected when they swallow this parasite. This is one reason why hands should be washed after contact with pets. Hands also should be washed after changing a childs diaper and after using the toilet.
  101. 101. Water-borne diseases - 9.2.4. Protozoa -Cryptosporidiosis• How serious is cryptosporidiosis?• Symptoms can last for up to 30 days in persons who are otherwise healthy.• In persons with weakened immune systems, including people with HIV/AIDS and cancer, transplant patients taking immunosuppressive drugs and people with genetically weakened immune systems, symptoms can persist indefinitely.• Persistent diarrhea due to cryptosporidiosis in these persons can lead to death.
  102. 102. Water-borne diseases - 9.2.4. Protozoa -Other protozoans• Entamoeba histolytica is carried by about 10% of the population in Europe and 12% in the USA.• In countries where the disease is wide spread the highest rate of incidence occurs in those groups with unprotected water supplies, in adequate waste disposal facilities, and poor personal hygiene.
  103. 103. Water-borne diseases - 9.2.4. Protozoa -Other protozoans• Naegleria are free living protozoans widely found in variety of surface and waste waters, especially surface waters that are heated (Marciano-Cabaral et al. 1988).
  104. 104. Water-borne diseases - 9.2.4. Protozoa -Other protozoans• Naegleria fowleri is the main human pathogenic species which was first reported in 1965 in Australia.• It normally enters the body through the nasal cavities while swimming in infected water.
  105. 105. Water-borne diseases - 9.2.4. Protozoa -Other protozoans
  106. 106. Water-borne diseases - 9.2.5. Parasitic worms -• The incidence of worm infection in European countries is generally low and is limited to Taenia and Ascaris.• Infection is normally contracted from animals reared for food, although many incidents of infection from contaminated water have been reported.• Ova of both genera are commonly isolated from sewage.
  107. 107. Water-borne diseases- 9.2.5. Parasitic worms -
  108. 108. Water-borne diseases - 9.2.5. Parasitic worms -• There are a number of other parasitic worms that can also be transmitted by faecal contamination of water supplies.• These include several hookworms, schistossomes, and a number of tapeworms, such as the fish tapeworm Diphyllobothrium latum.
  109. 109. Water-borne diseases- 9.2.5. Parasitic worms -
  110. 110. Water-borne diseases - 9.3. Indicator Organisms -• Group of microorganism use to reflect the quality and safety of a process food product – In water • Vibrio cholera • Salmonella typhi • Shigella spp • Hepatitis – In food • Coliform
  111. 111. Water-borne diseases - 9.3. Indicator Organisms - Criteria for use of an organism as an indicator• Must be associated with feces• Should not be a natural contaminant• Easy to detect• Test should be less complex than test for pathogen• Growth limit under conditions• Should not survive processing• Processing should have same effect on pathogens
  112. 112. Water-borne diseases - 9.3. Indicator Organisms -Suggested indicator organisms • Fecal organism – Fecal coliform – Escherichia coli • Enteric bacteria – Shigella spp. – Salmonella spp
  113. 113. Water-borne diseases - 9.3. Indicator Organisms - Coliforms• Coliform indicates processing contamination !• Coliform can grow on food processing equipment or !• in environment• Several genera are considered to be coliforms ! • Escherichia • Enterobactor • Klepsiella • Citrobactor
  114. 114. Coliforms• Source of coliform – Fecal group --GI tract of humans and animals ! – Non-fecal group --Soil and plant• Coliform group – Gram negative, rod shape, aerobic or facultative aerobic – non endospore former – ferments lactose at 30-37 ° C for 24-48 hrs
  115. 115. Water-borne diseases - 9.3. Indicator Organisms - Coliforms• Fecal coliform – found only in GI tract – can grow at elevated test temperature – ferment LST at 44.5 ° C for 24 hrs
  116. 116. Water-borne diseases - 9.3. Indicator Organisms - Coliforms• Methods for isolation of coliforms – Presumptive test • Liquid media (MPN) – LST (Lauryl Sulfate Tryptose) • Solid media – VRBA (Violet red bile agar)
  117. 117. Water-borne diseases - 9.3. Indicator Organisms - Coliforms• Confirm test – Liquid media (MPN) • BGLB (Brillant Green Lactose Bile broth) • EC (EC broth)
  118. 118. Water-borne diseases - 9.3. Indicator Organisms -Presumptive test of coliforms • LST – triplicate tubes for each dilution – incubate at 32-35 °C for 24-48 hrs – coliform grow---turbidity and gas • VRBA – surface plate method---spread on plate ! – C for 24-48 hrs ° incubate at 32-35 ! – red, purple colonies with ring of precipitate bile ! – salt around colonies
  119. 119. Water-borne diseases - 9.3. Indicator Organisms -Confirmation of coliforms • BGLB – Incubate at 32-35° C for 24-48 hrs – Coliform report as MPN • EC – Incubate at 44.5 ° C for 24 hrs – Fecal coliform report as MPN
  120. 120. Water-borne diseases - 9.3. Indicator Organisms -Identification of coliforms • Select colony or positive tubes and streak onto PCA slants • Identify the microorganism – Gram stain – Biochemical test » IMViC test • Indole test • Methyl red • Voges-Proskauer • Citrate utilization – Selective media • EMB agar (Eosin Methylene Blue Agar)
  121. 121. Water-borne diseases - 9.3. Indicator Organisms -Identification of coliforms • IMViC test: use to differentiate between the coliform group – Indoletest • Bacteria degrade tryptophan to indole – Methyl red • Bacteria produce acid from glucose – Voges-Proskauer • Detect acetylmethylcarbinol from glucose – Citrate utilization • Bacterial utilize citrate as a carbon source
  122. 122. Water-borne diseases - 9.3. Indicator Organisms -Identification of coliforms IMViC test
  123. 123. Water-borne diseases- 9.3. Indicator Organisms -
  124. 124. Water-borne diseases- 9.3. Indicator Organisms -
  125. 125. Water-borne diseases- 9.3. Indicator Organisms -
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