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Indicators for Waterborne Pathogens
Appendix A
Emerging and Reemerging Waterborne Pathogens
This appendix addresses a requirement of the committee’s statement of task; specifically the requirement to “. . . define currently known waterborne pathogen classes and anticipate those emerging waterborne pathogens that are likely to be of public health concern.” For the purposes of this report, emerging and reemerging pathogens can be defined as recently identified waterborne pathogens or those pathogens that were once thought to be under control from a public health perspective but are reappearing and causing increased incidence or geographic range of infections in exposed human populations. In recent years, several such waterborne pathogens have arisen, including recognized pathogens from fecal sources and some “new” pathogens from environmental sources. Several factors contribute to the (re)emergence of waterborne pathogens in the United States (Theron and Cloete, 2002), including the following:
Changes in human demographics. There is an increasing number of “vulnerable subpopulations” in the United States such as infants, children, pregnant women, the elderly, and the immunocompromised (e.g., AIDS patients) who are particularly susceptible to infections resulting from exposure to waterborne pathogens compared to the general populace (see also NRC, 2001).
Changes in human behavior. Urbanization of rural areas allows infections arising in formerly isolated areas, which may once have remained obscure and localized, to reach large and densely populated areas. The use of heated drinking water with warm water reservoirs also promotes the emergence of waterborne pathogens because these systems are ideal habitats for a number of pathogens of public health concern, such as Legionella spp. (Lee and West, 1991).
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Breakdown of public health systems. Although public health measures such as water and wastewater treatment act to minimize human exposure to waterborne pathogens and reduce the incidence of waterborne disease, these systems can and do fail on occasion—often with extensive public health ramifications. Such breakdowns also provide opportunities for pathogens to reemerge.
Microbial adaptation. Microbes are constantly evolving in response to changing environments and environmental conditions. With the increasing use and release of antibiotics and drugs into our waterways, strains of microorganisms that are antibiotic- or drug-resistant have also been increasingly identified (see Chapter 3 for further information).
Changes in agricultural practices. Intensive farming operations (especially concentrated/confined animal feeding operations, or CAFOs) result in high concentrations of animal wastes, which in turn lead to increased pollution of our nation’s waters by runoff and intentional (point source) discharges. This is of public health concern because a number of pathogens (e.g., Cryptosporidium) routinely contained in such fecal sources can be transmitted to humans through inadequately treated drinking water or through recreational water exposure.
Throughout this report, waterborne pathogens (including those that can be considered emerging or reemerging) can be categorized into four groups: viruses, bacteria, protozoa, and others. (“Others” include cyanobacterial toxins and protists; however, this group is not discussed extensively in this report for reasons outlined in Chapter 1.) Indeed, Chapter 3 on the ecology and evolution of waterborne pathogens and indicator organisms is divided into separate sections for viruses, bacteria, and protozoa. The issue of new and (re)emerging waterborne pathogens has been reviewed in several published reports and articles (EPA, 1998; LeChevallier et al., 1999; Szewzyk et al., 2000; Theron and Cloete, 2002) from a public health and/or water treatment perspective. Therefore, in response to the statement of task, this appendix includes a brief summary of the health effects and mode of transmission of select emerging and reemerging waterborne pathogens in all four groups taken from these and other sources (see Table A-1). Lastly, several of the waterborne pathogens listed in Table A-1 are discussed to some extent (in some cases extensively) elsewhere in this report.
REFERENCES
EPA (U.S. Environmental Protection Agency). 1998. Announcement of the Drinking Water Contaminant Candidate List; Notice. Federal Register 61(94): 24354-24388.
Hilton, C., K. Holmes, K. Spears, L.P. Mansfield, A. Hargreaves, and S.J. Forsythe. 2000. Arcobacter, newly emerging food and waterborne pathogens. Presentation at SGM Warwick, April 12.
LeChevallier, M.W., M. Abbaszdegan, A.K. Camper, G. Izaguirre, M. Stewart, D. Naumovitz, M. Mardhall, C.R. Sterling, P. Payment, E.W. Rice, C.J. Hurst, S. Schaub, T.R. Slifko, J.B. Rose, H.V. Smith, and D.B. Smith. 1999. Emerging pathogens: Names to know and bugs to watch out for. Journal of the American Water Works Association 91(9): 136-172.
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Lee, J.V., and A.A. West. 1991. Survival and growth of Legionella species in the environment. Journal of Applied Bacteriology Symposium Supplement 70: 121S-129S.
NRC (National Research Council). 2001. Classifying Drinking Water Contaminants for Regulatory Consideration. Washington, D.C.: National Academy Press.
Szewzyk, U., R. Szewzyk, and K.H. Schleifer. 2000. Microbiological safety of drinking water. Annual Review of Microbiology 54: 81-127.
Theron, J., and T.E. Cloete. 2002. Emerging waterborne infections: Contributing factors, agents, and detection tools. Critical Reviews in Microbiology 28: 1-26.
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TABLE A-1 Emerging and Reemerging Waterborne Pathogens of Public Health Concern
Waterborne Pathogen
Health Effects
Mode of Transmission
References and URLs
Viruses
Adenoviruses
Respiratory infections; gastroenteritis; febrile (fever-related) disease with conjunctivitis
Fecal-oral transmission; waterborne transmission
http://www.ce.berkeley.edu/~nelson/ce210a/Adenovirus/CE210a-adenovirus-k.htm; http://www.cdc.gov/ncidod/dvrd/revb/respiratory/eadfeat.htm; EPA, 1998
Astrovirus
Diarrhea
Fecal-oral transmission
Szewzyk et al., 2000
Coxsackieviruses
Diarrhea and vomiting; skin rashes; myocarditis and pericarditis (inflammation of the heart tissue and the membranous sac enveloping the heart, respectively); aseptic meningitis
Person-to-person transmission; fecal-oral transmission; contaminated water, particularly recreational water
http://www.awwarf.com/newprojects/pathogens/COXSACKI.html; EPA, 1998
Echoviruses
Subclinical infections; myocarditis; aseptic meningitis
Fecal-oral route
EPA, 1998
Enteroviruses
Gastroenteritis; poliomyelitis (inflammation of the gray matter of the spinal cord); meningitis; respiratory disease; diabetes; encephalitis (inflammation of the brain)
Fecal-oral route or respiratory route
LeChevallier et al., 1999; Theron and Cloete, 2002
Hepatitis viruses
Gastroenteritis
Fecal-oral route; fecally contaminated water and food; person-to-person transmission
LeChevallier et al., 1999
Norwalk/Caliciviruses
Diarrhea and vomiting
Contaminated surface water, groundwater, ice; contaminated shellfish; swimming in water containing sewage
EPA, 1998; LeChevallier et al., 1999
Rotavirus
Diarrhea
Fecally contaminated surface water
Szewzyk et al., 2000; Theron and Cloete, 2002
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Indicators for Waterborne Pathogens
Bacteria
Arcobacter
Diarrhea
Drinking water reservoirs and treatment plants
Hilton et al., 2000
Aeromonas hydrophila
Gastroenteritis
Drinking water biofilms
EPA, 1998; Theron and Cloete, 2002
Campylobacter (including C. jejuni, C. coli, and related species)
Acute gastroenteritis
Contaminated poultry products; unpasteurized milk; water
LeChevallier, et al., 1999; Szewzyk et al., 2000; Theron and Cloete, 2002
Helicobacter pylori
Gastroduodenal disease including chronic active gastritis; peptic and duodenal ulcer disease; gastric cancer
Unknown; fecal-oral transmission is highly probable
EPA, 1998; LeChevallier et al., 1999; Theron and Cloete, 2002
Legionella spp.
Legionnaires disease (severe lung inflammation) and Pontiac fever (influenza-like form of disease)
Source water to drinking water
Szewzyk et al., 2000
Mycobacterium avium complex
Pulmonary disease
Drinking water treatment and distribution system
EPA, 1998; LeChevallier et al., 1999
Pathogenic Escherichia coli
Hemorrhagic colitis (bleeding from inflamed colon) with bloody diarrhea and hemolytic-uremic syndrome (acute illness following a respiratory infection causing bloody diarrhea)
Contact with contaminated beef or dairy products
LeChevallier et al., 1999; Szewzyk et al., 2000; Theron and Cloete, 2002
Pseudomonas aeruginosa
Nosocomial infections (infections associated with hospital stays) in immunocompromised patients and patients with underlying diseases such as wound and urinary tract infections and pneumonia; tracheobronchitis in cystic fibrosis patients
Water exposed to fecal contamination; surface waters influenced by wastewater discharge; nutrient-rich water
Szewzyk et al., 2000
Yersinia enterocolitica
Gastrointestinal infections
Unknown; contaminated food and water are the most likely sources
Szewzyk et al., 2000; Theron and Cloete, 2002
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Indicators for Waterborne Pathogens
Waterborne Pathogen
Health Effects
Mode of Transmission
References and URLs
Protozoa
Acanthamoeba
Granulomatous amoebic encephalitis (swelling of the brain characterized by granulation tissue) in immunosuppressed people; keratitis (severe and potentially blinding infection of the cornea)
Contamination of contact lens or storage case
http://www.awwarf.com/newprojects/pathegeons/ACANTHAM.html; EPA, 1998
Cryptosporidium parvum
Subclinical infections and self-limiting diarrhea in healthy adults; severe diarrhea in infants and immunocompromised persons
Drinking water
Szewzyk et al., 2000; Theron and Cloete, 2002
Cyclospora cayetanensis
Diarrhea, abdominal cramping, decreased appetite, and low-grade fever that can last for several weeks
Unknown; fecal-oral route either directly or via water is thought to be highly probable
LeChevallier et al., 1999
Giardia lamblia
Subclinical infections and self-limiting diarrhea in healthy adults; severe diarrhea in infants and immunocompromised persons
Drinking water
Szewzyk et al., 2000; Theron and Cloete, 2002
Microsporidia
Diarrhea and cholangiopathy (infection of bile ducts) in immunocompromised persons
Surface water; sewage-contaminated waters
EPA, 1998; LeChevallier et al., 1999; Szewzyk et al., 2000
Toxoplasma gondii
Flu-like illness and/or swollen glands in the neck, armpits, or groin
Water contaminated by cats
LeChevallier et al., 1999
Other
Cyanobacteria toxins
Poisoning; gastrointestinal disease
Nutrient-rich surface water
EPA, 1998; LeChevallier et al., 1999; Szewzyk et al., 2000
Representative terms from entire chapter:
drinking water
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