Microbiological safety of drinking water

Transcription

1 Microbiological safety of drinking water ผ ช วยศาสตราจารย ดร. น นท กา ส นทรไชยก ล คณะสาธารณส ขศาสตร มหาว ทยาล ยธรรมศาสตร 08/06/59 drinking water 1

2 Sources of Water Supply Rain Surface: Impounding reservoirs Rivers and Streams Tanks/ Ponds/ Lakes Ground water Shallow wells Deep wells Springs 08/06/59 drinking water 2

3 Human right to water and sanitation (UNDESA) Sufficient. The water supply for each person must be sufficient and continuous for personal and domestic uses(drinking, personal sanitation, washing of clothes, food preparation, personal and household hygiene). 50 and 100 litres/person/day (WHO) Safe. (free from micro-organisms, chemical substances and radiological hazards that constitute a threat to a person's health). Acceptable (colour, odour and taste for each personal or domestic use) Physically accessible. (WHO: water source collection time should not exceed 30 minutes) 1,000 metres of the home and Affordable (be affordable for all: UNDP: should not exceed 3 % of household income) 08/06/59 drinking water 3

4 Safe Drinking Water Free from pathogenic agents Free from harmful chemicals Pleasant to taste Usable for domestic purposes 08/06/59 drinking water 4

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8 สถานการณ น าบร โภคในประเทศไทย ภาพรวม Source: กล มว จ ยและพ ฒนาค ณภาพน าบร โภค ส าน กส ขาภ บาลอาหารและน า 08/06/59 drinking water 8

9 ค ณภาพน าบร โภคในประเทศไทย พ.ศ พ.ศ 2556: ไม ผ านเกณฑ 08/06/59 drinking water 9

10 สถานการณ น าบร โภคในประเทศไทย: ด านจ ล นทร ย โคล ฟอร มแบคท เร ย และฟ คอลโคล ฟอร มแบคท เร ย 08/06/59 drinking water 10

11 Waterborne diseases/illness Gastro-intestinal problems Systemic illness Traditional pathogen- faecally contaminated pathogen o 88% of diarrhea cases worldwide are linked to unsafe water, inadequate sanitation or insufficient hygiene o 1.5 million deaths/year, mostly in young children New emerging pathogen o Virus- caliciviruses o Bacteria-E.coli O157:H7, Helicobacter sp., Mycobacterium avium complex o Protozoa-Cryptosporidium so., Cyclospora sp., Toxoplasma sp. 08/06/59 drinking water 11

12 Factors leading to waterborne outbreaks Newly recognised agents (Cryptosporidium, Giardia, Cyclospora) that have a high resistance to chemicals used in water treatment and development of antibiotic resistant strains of pathogens. Less immunity to pathogens eutrophication, changes in food chain structure, and unrestricted growth of nuisance species, creating breeding sites for vectorborne diseases. Changes in agricultural production methods, including high-density animal operations carried,leading to an increase in transmission of animal pathogens to humans. Ageing and deteriorating environmental infrastructure. 08/06/59 drinking water 12

13 Contamination pathway 08/06/59 drinking water 13

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16 defecation at water sources cross contamination from sewer lines, sewage disposal without any treatment seepage from septic tanks and pit latrines improper handling and storage of water at the home Agriculture, Industries, Livestock Urbanization Human migration Source of contamination 08/06/59 drinking water 16

17 Contamination pathways Water resource management Drinking water distribution system Drinking water vendors Consumers 08/06/59 drinking water 17

18 Transmission of pathogens through drinking water 08/06/59 drinking water 18

19 Major pathogens and parasites Bacteria oenteric bacteria (e.g., Salmonella, Shigella, Vibrio cholerae ) oindigenous aquatic bacteria. (e.g., Mycobacterium avium, Aeromonas ) Virus oaquatic environments /unable to multiply outside their host cells Protozoa oreleased into aquatic environments as cysts or oocysts/resistant to environmental stress and to disinfection in water and wastewater treatment plants 08/06/59 drinking water 19

20 Bacteria 08/06/59 drinking water 20

21 Bacteria Gram positive Gram negative Cocci Bacilli Cocci Rods 08/06/59 drinking water 21

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23 Microbial indicator Coliform bacteria Total coliform Fecal coliform E.coli Aerobic or facultatively anaerobic Gram negative non-spore-forming rod-shaped gas production during lactose fermentation within 48 hours at 35 C High numbers (2 x 10 9 per capita per day) in human and animal feces Pathogenic E.coli 08/06/59 drinking water 23

24 ข อควรจ า Coliforms may grow in aquatic environments, particularly if organic matter levels and temperatures are elevated Coliforms may form biofilms in drinking water distribution systems this is a problem because, for example, E. coli is 2400 times more resistant to chlorine in a biofilm than when planktonic Coliforms may recover from disinfectant injury More vulnerable to disinfection and environmental trauma than enteric viruses or parasites Do not necessarily indicate fecal contamination 08/06/59 drinking water 24

25 E.coli Morphology Gram - ve Straight rods, 1-3 X microns, Appear in singles or in pairs, Motile by peritrichate flagella. Very few strains non motile Not spore forming, Non acid fast. 08/06/59 drinking water 25

26 Classification of E.coli 1.Enteropathogenic 2.Enterotoxigenic 3.Enteroinvasive EPEC ETEC EIEC 4.Enterohemorrhagic EHEC 5.Enteroaggresive EAEC 08/06/59 drinking water 26

27 Enterohemorrhagic E. coli O157:H7 Flagella Hemorrhagic Bloody dysentery profuse diarrhea few leukocytes afebrile hemolytic-uremic syndrome hemolytic anemia thrombocytopenia (low platelets) kidney failure 08/06/59 drinking water 27

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29 Enterotoxigenic E. coli diarrhea like cholera milder travellers diarrhea 08/06/59 drinking water 29

30 Campylobacter sp. Gram-negative rods with comma, S, or gull-wing shapes. Motive, with a single polar flagellum No spore & no capsule 08/06/59 drinking water 30

31 Campylobacter - symptoms Incubation: 4-8d Acute enteritis: 1w, stools remain positive for 3 w Acute colitis Acute abdominal pain Bacteremia: <1% C. jejuni Septic abortion Reactive arthritis diarrhea malaise fever abdominal pain usually self-limiting ภาวะแทรกซ อน -Guillain-Barré syndrome (GBS) 08/06/59 drinking water 31

32 Helicobacter sp. associated with antral gastritis, gastric ulcers, and gastric carcinoma. Gram negative rod, curved, Very Motile corkscrew motion Microaerophilic, needs 10% CO 2 and 5% O 2 08/06/59 drinking water 32

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35 Diarrhoeal Viruses 08/06/59 drinking water 35

36 Viral Gastroenteritis It is thought that viruses are responsible for up to 3/4 of all infective diarrhoeas. Viral gastroenteritis is the second most common viral illness after upper respiratory tract infection. In developing countries, viral gastroenteritis is a major killer of infants who are undernourished. Rotaviruses are responsible for half a million deaths a year. Many different types of viruses are found in the gut but only some are associated with gastroenteritis. 08/06/59 drinking water 36

37 Viruses found in the gut Rotaviruses Adenoviruses Caliciviruses Norwalk like viruses or SRSV (Small Round Structured Viruses) 08/06/59 drinking water 37

38 Also found in other mammals and birds, causing diarrhoea. Account for 50-80% of all cases of viral gastroenteritis. Usually endemic, but responsible for occasional outbreaks. Causes disease in all age groups but most severe symptoms in neonates and young children. Asymptomatic infections common in adults and older children. Symptomatic infections again common in people over 60. Rotaviruses 08/06/59 drinking water 38

39 Rotaviruses Up to 30% mortality rate in malnourished children, responsible for up to half a million deaths per year. 80% of the population have antibody against rotavirus by the age of hr incubation period followed by an abrupt onset of vomiting and diarrhoea, a low grade fever may be present. Live attenuated vaccines now available for use in children. 08/06/59 drinking water 39

40 Rotavirus is the Leading Cause Of Severe Gastroenteritis in Children <5 Years Developed Countries Developing Countries Unknown Unknown Rotavirus Rotavirus Bacterial Other Bacterial Other 08/06/59 A. Kapikian, drinking Fields water Virology

41 Global Distribution of 527,000 Annual Rotavirus Deaths in Young Children 1 dot = 250 deaths 08/06/59 drinking water 41

42 Clinical Features Range from asymptomatic to severe diarrhea First infection more severe than subsequent Maximal disease incidence in infants 6-24 months Up to 30% of adult cases are symptomatic Symptoms include Fever Nausea/vomiting Watery diarrhea without blood/mucous Dehydration/electrolyte imbalance lead to hospitalization and death 08/06/59 drinking water 42

43 Hepatitis A a viral liver disease that can cause mild to severe illness. transmitted through ingestion of contaminated food and water or through direct contact with an infectious person. Almost everyone recovers fully from hepatitis A, but very small proportions die from fulminant hepatitis. associated with a lack of safe water and poor sanitation. Improved sanitation and the hepatitis A vaccine are the most effective ways to combat the disease. 08/06/59 drinking water 43

44 Body Fluids CONCENTRATION OF HEPATITIS A VIRUS IN VARIOUS BODY FLUIDS Feces Serum Saliva Urine Source: Viral Hepatitis and Liver Disease 1984;9-22 J Infect Dis 1989;160: Infectious Doses per ml 08/06/59 drinking water 44

45 Geographic distribution of hepatitis A virus infection 08/06/59 drinking water 45

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47 Waterborne Protozoa Cryptosporidium Giardia Entamoeba Naegleria Toxoplasma Acanthamoeba 08/06/59 drinking water 47

48 Characteristics of Infection low numbers of parasites required to initiate infection multiplication in the host- transmission self-limiting - except immundeficient individuals Zoonosis - cross-species transmission 08/06/59 drinking water 48

49 Cryptosporidium parvum 08/06/59 drinking water 49

50 What is it? Cryptosporidium is a coccidian protozoan parasite It is associated with municipal water supplies which causes diarrhea Cryptosporidium parvum causes the disease Cryptosporidiosis. The pathogenic form of C. parvum is the oocyst which is 3 um in diameter (half the size of a red blood cell). 08/06/59 drinking water 50

51 Definitive Host / Intermediate Host: Definitive Host: Human Reservoir Hosts: kittens, puppies, goats, calves, mice It is a zoonotic disease and can travel from animals to humans. Cryptosporidium parvum has been recognized as a human pathogen since /06/59 drinking water 51

52 Life cycle: 08/06/59 drinking water 52

53 Cryptosporidium: Public Health Significance Worldwide prevalence about 10% Zoonosis, human and animal genotypes Oocysts ubiquitous in surface waters Difficult to remove, and hard to kill Drinking water - amplifier for disease Up to 20% of general population may be considered at higher risk 08/06/59 drinking water 53

54 Cryptosporidiosis: The Disease Serious disease in the young, pregnant women, patients undergoing chemotherapy and elderly Potentially fatal in immuno-compromise hosts Infectious dose in healthy humans is low No effective chemotherapy available 08/06/59 drinking water 54

55 Giardia lambia: The Organism obligate intestinal parasites of all classes of vertebrates more than 100 described species two stages in the life cycle: the motile trophozoites that inhabit the small intestine of the host, and the resistant cysts found in the environment 08/06/59 drinking water 55

56 G. lamblia life cycle 08/06/59 drinking water 56

57 G. lamblia life cycle Infection initiated by the ingestion of infectious cysts (only 10 are required for infection) Acid in the stomach stimulates the release of trophozoites from the cyst Trophozoites are released in the duodenum and jejunum (upper part of small intestines) where they multiply by binary fission Trophozoites attach to the intestinal villi by means of a sucking disk Trophozoites can develop into cysts for survival outside of the host Trophozoites cause an explosive diarrhea such that cysts are released into the environment Trophozoites remain in the G-I tract and almost never found elsewhere in the body. 08/06/59 drinking water 57

58 Epidemiology of G. lamblia G. lamblia found everywhere in the world Approximately 50% of infected humans are asymptomatic and are important carriers of disease Giardiasis is acquired through o the consumption of inadequately treated water o ingestion of uncooked vegetables and fruits o person-person spread (esp. daycare centers, families with o infected children) Giardia can be maintained in the municipal water supply, unless water treatment plant uses filtration and chemicals to eradicate the protozoa 08/06/59 drinking water 58

59 Giardiasis: Public Health Significance Worldwide prevalence about 8%, much higher in endemic areas Zoonosis Most prevalent in day care centers, mental institutions, male homosexuals Children, elderly and immunodeficient persons more susceptible Transmitted by direct contact, food or water Chemotherapy available- some drug resistance 08/06/59 drinking water 59

60 Giardiasis: The Disease asymptomatic: largest group symptomatic: self-limiting infection, diarrhea, abdominal cramps,fever, nausea and weight loss symptomatic: chronic infection, immunodeficient individuals, malabsorption, food intolerance, chronic inflammation of the mucosa 08/06/59 drinking water 60

61 Current Drinking water quality: Microbiological quality E.coli Pseudomonas aeruginosa Clostridium perfringens THA EU USEPA JP Not to be detected 0 in 250 ml Not to be detected 0 in 250 ml <1/100mL to <1000/mL 0 in 100 ml Coliform 2.2 /100ml 0 in 100 ml <1 in 100 ml Total Plate Counts ไม เก น 500 cfu/ml 500 cfu/ml 100/ml Giardia lamblia จ ล นทร ย ท ท าให เก ดโรค Not to be detected 08/06/59 drinking water 61

62 Monitoring and control of drinking water quality Criteria for selection of parameters ohealth-related parameter oparameter listed in legislation oparameter for process control o Early-warning parameter oemerging water quality parameter. Usually these are not new parameters, but they have recently emerged as being of interest. odetectable by simple, rapid and inexpensive method 08/06/59 drinking water 62

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