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Water Microbiology/Microbial Contaminants

Water Microbiology/Microbial Contaminants. Gwy-Am Shin Office: Suite 2335, 4225 Roosevelt Phone: 206-543-9026 Email: gwyam@u.washington.edu. Microbiological Contaminants. Most benign, “normal” Some are frank pathogens

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Water Microbiology/Microbial Contaminants

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  1. Water Microbiology/Microbial Contaminants Gwy-Am Shin Office: Suite 2335, 4225 Roosevelt Phone: 206-543-9026 Email: gwyam@u.washington.edu

  2. Microbiological Contaminants • Most benign, “normal” • Some are frank pathogens • Microbial pathogens usually are not “normal flora” of humans; Oppurtunisitic pathogens • Some are “normal flora” of animals: • Salmonella enteriditis and Campylobacter jejuni in poultry • “Normal flora” for local populations may be pathogenic for visitors and transient populations: • “Traveller’s diarrhea” due to local strains of E. coli • Some “normal flora” are pathogenic for sensitive populations, such as immunocompromised persons

  3. Occurrence of Enteric Microbial Pathogens in Humans and Pathogen Shedding • Enteric (gastrointestinal) illnesses are second only to respiratory illnesses in the population • Most people get 1 enteric illness per year: • Annual illness rates are even higher in infants, children, the elderly, child caregivers, health professionals, the poor, male homosexuals and other high risk groups • Not all enteric infections produce illness (asymptomatic or sub-clinical infections) • So, rates of infection are even higher (by perhaps 2 to 100 times) • People (and animals) with enteric infections fecally excrete high concentrations of pathogens for days, weeks, months or longer. • Pathogen concentrations can be >106 to >109 per gram of feces. • Community pathogen shedding is often 1-10% at any time.

  4. Transmission of enteric pathogens

  5. Incidence and concentration of enteric pathogens in feces (USA)

  6. Viruses: smallest (0.02-0.3 µm diameter); simplest: nucleic acid + protein coat (+ lipoprotein envelope) Bacteria: 0.5-2.0 µm diameter; prokaryotes; cellular; simple internal organization; binary fission. Protozoa: most >2 µm- 2 mm; eucaryotic; uni-cellular; non-photosynthetic; flexible cell membrane; no cell wall; wide range of sizes and shapes; hardy cysts Groups: flagellates, amoebae, ciliates, sporozoans (complex life cycle) and microsporidia. , rigid cell wall, most eukaryotic Algae: wide range of sizes and shapes; photosynthetic. Helminths (Worms): multicellular animals; some are parasites; eggs are small enough (25-150 µm) to pose health risks from human and animal wastes in water.

  7. THE MICROBIAL WORLD: SIZES OF MICROBES Parasites are visible by light microscopy

  8. Viruses • Smallest (0.02 – 0.3 µm) • Simplest • Nucleic acids (DNA or RNA) • Protein capsid

  9. Human enteric viruses

  10. Bacteria • Size: 0.5 –2.0 µm • Simple internal organization • Envelope: cytoplasmic membrane, cell wall, and capsule • Appendages: flagella and/or pili • Spores: environmentally resistant form

  11. Human pathogenic bacteria

  12. Human pathogenic bacteria

  13. Procaryotic Cell (left) and Eucaryotic Cell (right)

  14. Protozoa • Size: 2 – 2000 µm • Complex internal organization (nucleus, mitochondria, etc) • Very complex life cycle (inside and outside of their hosts) • Flagellates, amoeba, ciliates, and sporozoans • (Oo)cysts: environmentally resistant form

  15. Human protozoan parasites

  16. Algae • Photosynthetic • Rigid cell wall • Wide range of sizes and shapes • 2 micrometers and larger Nostoc Anabaena and Aphanocapsa

  17. Helminths (Worms) • Multicellular animals • Some are human and/or animal parasites • Eggs are small enough to pose environmental health problems from human and animal excreta in water, food, soil, etc. • Several major groups: • Nematodes (roundworms): ex. Ascaris • Trematodes (flukes; flatworms): ex. Schistosomes • Cestodes (tapeworms): pork and beef tapeworms

  18. Helminths • Multicellualr animals • Size: up to 30 cm • Highly differentiated structures • Very complex life cycle (inside and outside of their hosts) • Nematodes, Trematodes, and Cestodes • Eggs: environmentally resistant form

  19. Human helminth parasites

  20. Bacteria

  21. Shigella spp. • Elongated and straight rods • Size: 0.5-1 µm • Four species: dysenteriae, flexneri, sonnei, and boydii • Watery or bloody diarrhea, abdominal pain, fever, and malaise • fatality may be as high as 10-15% with some strains

  22. Shigella spp.: Epidemiology • Involved in 44 drinking water outbreaks with 9,196 cases and 34 recreational water outbreaks with 2,329 cases in USA (1971-2000) • Incidence • 14,000 (lab-confirmed) and 448,240 (estimated) cases in USA • 164.7 million (estimated) case (163.2 in developing countries and 1.5 in developed countries) and 1.1 million death worldwide • 580,000 cases in travelers • Reservoirs: humans and primates • Infectious dose: ~ 10 cells • Incubation period: typically 1-3 days • Duration of illness: 2-7 days • Mode of transmission: Direct (person-to-person) and indirect (fomites, water, and food)

  23. Escherichia coli O157: H7 • Elongated and straight rods • Size: 0.5-1 µm • ~8,000 serotypes • Acute bloody diarrhea and abdominal cramps with little or no fever • 3-5% fatality.

  24. Escherichia coli O157: H7 : Epidemiology • Involved in 11 drinking water outbreaks with 529 cases and 15 recreational water outbreaks with 387 cases in USA (1971-2000) • Incidence • 730,000 (estimated) cases (USA) • 210 million cases and 300,000 deaths worldwide • Many different serotypes: enterotoxigenic (ETEC); enteropathogenic (EPEC); enteroinvasive (EIEC); and enteroaggregative (EAgg EC) • All pathogenic E. coli: 1.5 billion (estimated) case and 3 million death worldwide • Reservoirs: humans and animals (cattle, goats, sheep, deer, ….) • Infectious dose: ~ 100 cells • Incubation period: typically 1-3 days • Duration of illness: 2-12 days • Mode of transmission: Direct (person-to-person) and indirect (fomites, water, and food)

  25. Salmonella spp. • Elongated and straight rods • >2,000 serotypes • Diarrhea, fever, headache, constipation, malaise, chills, and myalgia • 12% - 30% mortality

  26. Salmonella spp. : Epidemiology • Involved in 12 drinking water outbreaks with 2,370 cases in USA (1971-1992) • Incidence • An estimated1.4 million cases with 500 death in the United States • An estimated 21 million cases of typhoid fever and 200,000 deaths occur worldwide. • Reservoirs: humans and animals (cattle, chicken, turkey…) • Infectious dose: ~100 cells • Incubation period: typically 1-3 days • Duration of illness: 2-7 days • Mode of transmission: Direct (person-to-person) and indirect (fomites, water, and food)

  27. Vibrio cholerae • Straight or curved rods • Motile with flagella • 0.5-0.8 µm in width and 1.4-2.6 µm in length • Serogroup O1 or O139 • Profuse watery diarrhea, vomiting, circulatory collapse and shock. • 40 - 60 % of typical cases are fatal if untreated

  28. Vibrio spp. : Epidemiology • Involved in 2 drinking water outbreaks with 28 cases in the USA (1971-2000) • Incidence • 0-5 cases per year in the United States. • A major cause of epidemic diarrhea throughout the developing world. • Ongoing global pandemic in Asia, Africa and Latin America for the last four decades. • Reservoirs: humans, environmental reservoirs - waters may be associated with copepods or other zooplankton • Infectious dose: ~100 cells • Incubation period:a few hours to 5 days; usually 2-3 days • Duration of illness: several days • Mode of transmission: Indirect (water and food)

  29. Campylobacter spp. • Curved rod • Size: 1.5-3 microns • C. jejuni and C. coli • fever, nausea, abdominal cramps, (seldom) vomiting, and bloody diarrhea

  30. Campylobacter spp. : Epidemiology • Involved in 16 drinking water outbreaks with 5473 cases in the USA (1971-2000) • Incidence • An estimated 2.4 million persons are affected each year. • Reservoirs: humans and animals (cattle, chicken, birds, …) • Infectious dose: ~100 cells • Incubation period: 3-5 days • Duration of illness: 2-10 days • Mode of transmission: Direct (animal contact) and indirect (food and water)

  31. Other Important Bacterial Pathogens • Fecal origin • Aeromonas spp. • Plesomonas spp. • Yersinia spp. • Environmental origin • Legionella spp. (esp. L. pneumophila) • Pseudomonas spp. (esp. P. aeruginosa) • Mycobacterium Avium Complex (MAC)

  32. Nuisance Bacteria • Acintomycetes/Streptomycetes • Thin filamentous, gram postive rods • Taste and odor • Iron Bacteria • E.g. Leptothrix, Thiobacillus, Clonothrix, Sphaerotilus, Caulobacter, Hyphomicrobium • Main corrosion • Increase oxidant demand • Sulfur Bacteria • E.g. Desulfovibrio, Thiothrix, Chlorobium, Chromatium, Thiobacillus • Formation of tubercles; pipe corrosion; increase oxidant demand • Reduce Sulfur compounds to H2Sa • Nitrifying bacteria • E.g. Nitrosomonas, Nitrobacter, Nitrospira, Nitrococcus • Increased oxygen demand (Nitrite);

  33. Protozoan Pathogens

  34. Waterborne Outbreaks in the United States, 1989-1994 Etiologic Agent No. Outbreaks No. Cases Acute GI (unknown) 44 16,264 Cryptosporidium parvum8 406,822 Giardia lamblia16 1,205 Hepatitis A virus 4 81 Norwalk-like viruses 1 900 E. coli O157:H7 1 243 Cyclospora cayatenensis1 21 Shigella spp. 7 570 Salmonella sp. 1 625 Vibrio cholerae (non-01) 1 11 Chemicals: Pb, NO3, F and Cu 13 394 TOTAL 87 427,256

  35. Protozoa • Size • Usually 10-50 µm • smallest: 1-10 µm, largest: 150 µm (Balantidium coli) • Many organells • Nucleus (or nuclei) • Cytosome (cell mouth), food vacuoles, contractile vacuoles (osmoregulation), Golgi apparatus, mitochondria, lysosomes,… • Locomotive structures: pseudopodia, flagella, cilia • Cell cycle and reproduction • Asexual (binary fission) and sexual (various life stages)

  36. Prokaryotic Cell (left) and Eukaryotic Cell (right)

  37. Enteric Protozoans: Taxonomy Protozoans (single-celled): • Sarcodina: Amoebas: ex.: Entamoeba histolytica • Mastigophora: Flagellates: ex.: Giardia lamblia • Sporozoa: Coccidians: Cryptosporidium parvum • Ciliophora: Ciliates: ex.: Balantidium coli • Microsporidia: ex.: Enterocytozoon beinusi

  38. Entamoeba histolytica • Ameba • Cyst • 10-20 μm • 4 nuclei • chromatoidal bars • Trophozoite • 12-50 μm • 1 nucleus • actively mobile • Mild GI symptoms (abdominal pain, cramps, colitis and diarrhea), bloody diarrhea (amoebic dysentery)

  39. Entamoeba histolytica: Epidemiology • Involved in 1 drinking water outbreaks with 4 cases and 40 recreational water outbreaks with 11,707 cases in USA (1971-2000) • Incidence • 4 % prevalence in USA • 50 % prevalence with 100,000 deaths per year worldwide • Reservoir: human is the only host • Infectious dose: unknown; however, theoretically, the ingestion of one viable cyst can cause infection • Incubation period: 1-4 weeks • Transmission: Direct transmission (sexually transmission), fecal-oral route, waterborne, foodborne • High risk groups: travelers, recent immigrants, male homosexuals, institutioned populations

  40. Giardia lamblia • Flagellate • Cyst • 8-14 μm • 2-4 nuclei • thick oocyst wall (0.3 μm) • Trophozoite • Heart-shaped, symmetric • 10-18 μm long, 6-8 μm wide • 2 nuclei • 8 flagella • abdominal cramps, nausea, vomiting, anorexia, low-grade fever, flu-like headache, general malaise, weakness, weight loss, distension, and profuse, greasy, bulky and foul-smelling diarrhea

  41. Giardia lamblia: Epidemiology • Involved in 126 drinking water outbreaks with 28,426 cases and 16 recreational water outbreaks with 684 cases in USA (1971-2000) • 500,000 estimated cases (200 millions?) worldwide • Reservoir: Human and animals (dogs, beaver, muskrat, elk, deer, voles, mice, horses, sheep, …) • Infectious dose: ~10 cysts • Incubation period: 1-14 days • Duration of illness: 1-3 weeks • Transmission: Fomites, waterborne, foodborne • High risk groups: children (in day-care centers), immunosuppressed people, and institutioned populations

  42. Cryptosporidium parvum • Coccidia • Oocyst • 4 - 6 m • 4 sporozoites • Thick oocyst wall • Sporozoite • No locomotive structure • Immunocompetent people: similar to giardiasis • Immunocompromised people: life-threating • Fluid loss: 2-6liter/day (17 liters/day) • Extra-intestinal infection: respiratory cryptosporidiosis (intestitial pneumonia)

  43. Cryptosporidium parvum: Epidemiology • Involved in 15 drinking water outbreaks with 421,473 cases and 40 recreational water outbreaks with 11,707 cases in USA(1971-2000) • Incidence • 1 – 3 % prevalence in USA • 5 % (Asia) and 10 % (Africa) prevalence • Reservoir: Human and animals (calves, lambs, goats,horses, pigs, deer, squirrel, beaver, muskrat,woodchuck,rabbit, dogs, fox, cat, skunk, raccon, bear, …) • Infectious dose: < 10 cysts • Incubation period: 7 days • Duration of illness: 1-4 weeks • Transmission: Fomites, waterborne, foodborne • High risk groups: children, immunosuppressed people, institutioned populations

  44. Emerging Protozoan Parasites • Toxoplasma gondii • Microsporidia spp.

  45. Toxoplasma gondii (oocysts) • Apicomplexa (Coccidia) • Oocyst • Two phases • A: unsporulated • B: sporulated • 10 – 13 m • two sporocysts • four sporozoites • distinctive cell walls • two or three layers • scatter UV • highly persistent in the environment • soil (months) • moist conditions (years)

  46. Toxoplasma gondii (other infectious forms) • Tachyzoite • Crescent-shaped • 2X6 m • Rapidly multiflying • Transmitted through placenta • Bradyzoite • Slowly multiplying • Tissues in intermediate hosts • Reproduction • Both asexual (intermediate hosts) and sexual (definitive hosts: cats)

  47. Transmission of Toxoplasma gondii

  48. Toxoplasma gondii: Epidemiology • Worldwide • 22.5 % prevalence (general population) in USA between 1988-1994 • Half billion people in the world • Unusually high prevalence in France (65-85%): raw or undercooked meat • High prevalence in Central America: large number of stray cats • Symptoms • Immunocompetent people: mostly asymptomatic, some flu-like symptoms (swollen lymph glands, muscle aches and pains) • Immunocompromised people: life-threating • central nerve system disease (encephalitis) • blindness, myocarditis, pneumonia • Congenital infected children • impaired vision and mental retardation • Reservoir: Definitive hosts are cats; intermediate hosts are sheep, goats, rodents, swine, cattle, chicken, and birds • Infectious dose: Not known • Incubation period: 10-23 days • Transmission: Indirect (water and food) and transplacental • High risk groups: infants born to infected mothers, immunosuppressed people

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