Water MicrobiologyMicrobial Contaminants - PowerPoint PPT Presentation

Title: Water MicrobiologyMicrobial Contaminants


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Water Microbiology/Microbial Contaminants
Gwy-Am Shin Office Suite 2335, 4225
Roosevelt Phone 206-543-9026 Email
gwyam_at_u.washington.edu
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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
• Travellers diarrhea due to local strains of E.
  coli
• Some normal flora are pathogenic for sensitive
  populations, such as immunocompromised persons

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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 gt106 to gt109 per
  gram of feces.
• Community pathogen shedding is often 1-10 at any
  time.

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Transmission of enteric pathogens
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Incidence and concentration of enteric pathogens
in feces (USA)
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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 gt2
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.
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THE MICROBIAL WORLD SIZES OF MICROBES
Parasites are visible by light microscopy
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Viruses

• Smallest (0.02 0.3 µm)
• Simplest
• Nucleic acids (DNA or RNA)
• Protein capsid

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Human enteric viruses
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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

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Human pathogenic bacteria
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Human pathogenic bacteria
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Procaryotic Cell (left) and Eucaryotic Cell
(right)
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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

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Human protozoan parasites
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Algae

• Photosynthetic
• Rigid cell wall
• Wide range of sizes and shapes
• 2 micrometers and larger

Nostoc
Anabaena and Aphanocapsa
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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

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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

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Human helminth parasites
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Bacteria
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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

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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)

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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.

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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)

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Salmonella spp.

• Elongated and straight rods
• gt2,000 serotypes
• Diarrhea, fever, headache, constipation, malaise,
  chills, and myalgia
• 12 - 30 mortality

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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)

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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
  

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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)

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Campylobacter spp.

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

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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)

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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)

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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)

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Protozoan Pathogens
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Waterborne Outbreaks in the United States,
1989-1994
Etiologic Agent No. Outbreaks No. Cases Acute GI
(unknown) 44 16,264 Cryptosporidium
parvum 8 406,822 Giardia lamblia 16 1,205 Hepat
itis A virus 4 81 Norwalk-like
viruses 1 900 E. coli O157H7 1 243 Cyclospora
cayatenensis 1 21 Shigella spp. 7 570 Salmonell
a sp. 1 625 Vibrio cholerae (non-01) 1 11 Chemi
cals Pb, NO3, F and Cu 13 394 TOTAL 87 427,
256
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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)

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Prokaryotic Cell (left) and Eukaryotic Cell
(right)
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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

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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)

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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

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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

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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

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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)

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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 lt 10 cysts
• Incubation period 7 days
• Duration of illness 1-4 weeks
• Transmission Fomites, waterborne, foodborne
• High risk groups children, immunosuppressed
  people, institutioned populations

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Emerging Protozoan Parasites

• Toxoplasma gondii
• Microsporidia spp.

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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)

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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)

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Transmission of Toxoplasma gondii
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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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Microsporidia spp.

• New Phylum
• 143 genera, gt1200 species
• 14 identified human pathogens
• Produce very resistant spores
• Usuaually small (1-4 ?m)
• A unique organalle (polar tubule)
• Coiled inside the spores
• Inject infective spore contents into the host
  cells

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Life cycle of Microsporidia spp.
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Microsporidia spp. Epidemiology

• Worldwide
• Both developed and developing countries
• Symptoms
• Immunocompetent people asymptomatic or
  self-limiting diarrhea
• Immunocompromised people
• Chronic diarrhea
• Disseminated diseases (keraconjunctivitis,
  bronchitis, pnuemonia, hepatitis, )
• Reservoirs human and animals (rabbits, mice,
  dogs, pigs, cats, cattle, wild birds (parrots),
  insects?)
• Infectious dose Not known
• Incubation period Not known
• Transmission uncertain
• Airborne transmission?
• Waterborne transmission??
• Transplacental transmission? (Encephalitozoon
  spp.)

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Other Important Protozoa

• Trypanosomes- Sleeping Sickness
• African (Tsetse flies)
• American (kissing bugs) Chagas
• Acanthamoeba spp. (GAE)
• Balamuthia mandrillaris (GAE)
• Naeglaria fowlerii (PAM)
• Pneumocystis carinii (now P. jiroveci a fungus)

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