Download Indicator Organisms

Water Microbiology/Microbial
Contaminants
Gwy-Am Shin
Office: Suite 2335, 4225 Roosevelt
Phone: 206-543-9026
Email: [email protected]
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
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.
Transmission of enteric pathogens
Incidence and concentration of enteric
pathogens in feces (USA)
Pathogen
Enteric virus
Hepatitis A
Rotavirus
Salmonella
Giardia
Cryptosporidium
Incidence (%)
10-40
0.1
10-29
0.5
3.8
18-54
0.6-20
27-50
Concentration(/gram)
103-108
108
1010-1012
104-1010
106
106
106-107
106-107
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.
THE MICROBIAL WORLD:
SIZES OF MICROBES
Parasites are visible by light microscopy
Viruses
• Smallest (0.02 – 0.3
µm)
• Simplest
– Nucleic acids (DNA or
RNA)
– Protein capsid
Human enteric viruses
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
Human pathogenic bacteria
Human pathogenic bacteria
Procaryotic Cell (left) and Eucaryotic Cell (right)
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
Human protozoan parasites
Algae
• Photosynthetic
• Rigid cell wall
• Wide range of
sizes and shapes
Nostoc
– 2 micrometers and
larger
Anabaena and Aphanocapsa
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
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
Human helminth parasites
Bacteria
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
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)
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.
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)
Salmonella spp.
• Elongated and
straight rods
• >2,000 serotypes
• Diarrhea, fever,
headache,
constipation, malaise,
chills, and myalgia
• 12% - 30% mortality
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)
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
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)
Campylobacter spp.
• Curved rod
• Size: 1.5-3 microns
• C. jejuni and C. coli
• fever, nausea,
abdominal cramps,
(seldom) vomiting, and
bloody diarrhea
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)
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)
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);
Protozoan Pathogens
Waterborne Outbreaks in the
United States, 1989-1994
Etiologic Agent
No. Outbreaks
Acute GI (unknown)
44
Cryptosporidium parvum
8
Giardia lamblia
16
Hepatitis A virus
4
Norwalk-like viruses
1
E. coli O157:H7
1
Cyclospora cayatenensis
1
Shigella spp.
7
Salmonella sp.
1
Vibrio cholerae (non-01) 1
Chemicals:
Pb, NO3, F and Cu
13
No. Cases
16,264
406,822
1,205
81
900
243
21
570
625
11
TOTAL
427,256
87
394
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)
Prokaryotic Cell (left) and Eukaryotic Cell (right)
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
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)
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
Giardia lamblia
•
•
Flagellate
Cyst
–
–
–
•
Trophozoite
–
–
–
–
•
8-14 μm
2-4 nuclei
thick oocyst wall (0.3 μm)
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
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
Cryptosporidium parvum
•
•
Coccidia
Oocyst
•
Sporozoite
– 4 - 6 m
– 4 sporozoites
– Thick oocyst wall
– No locomotive structure
•
•
Immunocompetent people: similar to
giardiasis
Immunocompromised people: lifethreating
• Fluid loss: 2-6liter/day (17
liters/day)
• Extra-intestinal infection:
respiratory cryptosporidiosis
(intestitial pneumonia)
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
Emerging Protozoan Parasites
• Toxoplasma gondii
• Microsporidia spp.
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)
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)
Transmission of Toxoplasma gondii
Toxoplasma gondii: Epidemiology
•
Worldwide
–
–
22.5 % prevalence (general population) in USA between 1988-1994
Half billion people in the world
•
•
•
Symptoms
–
–
–
•
•
•
•
•
Unusually high prevalence in France (65-85%): raw or undercooked meat
High prevalence in Central America: large number of stray cats
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
Microsporidia spp.
• New Phylum
– 143 genera, >1200 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
Life cycle of Microsporidia spp.
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.)
Other Important Protozoa
• Trypanosomes- Sleeping Sickness
– African (Tsetse flies)
– American (kissing bugs) “Chaga’s”
•
•
•
•
Acanthamoeba spp. (GAE)
Balamuthia mandrillaris (GAE)
Naeglaria fowlerii (PAM)
Pneumocystis carinii (now P. jiroveci a
fungus)