Table 1.

Selected pathogens that can be transmitted by water

Organism	Disease	Incubation Period	Duration of Illness	Health Significancea	Resistance to Chlorineb
Bacteria
Burkholderia pseudomallei	Pneumonia			High	Low
Campylobacter	Gastroenteritis	3–5 days	1–4 days	High	Low
Legionella	Pontiac fever	5–66 h	2–7 days	High	Low
	Pneumonia	2–14 days	Weeks to months	High	Low
Leptospira	Weil's disease (headache, chillls, fever, nausea, neck or joint pain)	2–20 days	3 days to 3 weeks	High	Low
Shiga-toxin producing E. coli	Gastroenteritis, hemolytic uremic syndrome, kidney failure	12 h - 8 days	1 day to 3 weeks	High	Low
Salmonellca enterica serovar typhi	Typhoid fever	7–28 days	Weeks to months	High	Low
Salmonella	Salmonellosis	8–48 h	3–5 days	High	Low
Shigella	Bacillary dysentery	1–7 days	4–7 days	High	Low
Vibrio cholerae O1	Profuse, watery diarrhea, vomiting, rapid dehydration	9–72 h	3–4 days	High	Low
Vibrio cholerae non-O1	Watery diarrhea	1–5 days	3–4 days	High	Low
Yersinia enterocolitica	Gastroenteritis	2–7 days	1–21 days	Moderate	Low
Protozoa
Cryptosporidium parvum	Diarrhea	1–2 weeks	4–21 days	High	High
Cyclospora cayatanensis	Watery diarrhea alternating with constipation	2–11 days	days	High	High
Entamoeba histolytica	Amoebic dysentery	2–4 weeks	weeks to months	High	High
Giardia intestinalis	Diarrhea, malabsorption	5–25 days	weeks to months	High	High
Microsporidium	Chronic diarrhea, weight loss
Naegleria fowleri	Primary amoebic meningoencephalitis	Minutes to hours		High	Low
Toxoplasma gondii	Toxoplasmosis			High	High
Viruses
Adenovirus	Respiratory illness, conjunctivitis, vomiting, diarrhea	1–4 days	2–3 days	Moderate	Moderate
Astrovirus	Vomiting, diarrhea	3–4 days	2–7 days	Moderate	Moderate
Calicivirus	Vomiting, diarrhea			Moderate	Moderate
Coronavirus	Vomiting, diarrhea			Moderate	Moderate
Enterovirus:		3–14 days	variable
Poliovirus	Paralysis, meningitis, fever			High	Moderate
Coxsackie A	Meningitis, fever, herpangina, respiratory illness, paralysis			High	Moderate
Coxsackie B	Myocarditis, congenital heart anomalies, rash, fever, meningitis, respiratory illness, pleurodynia			High	Moderate
Echovirus	Meningitis, encephalitis, respiratory illness, rash, diarrhea, fever, myocarditis, endocarditis			High	Moderate
Enterovirus 68–71	Meningitis, encephalitis, respiratory illness, acute hemorrhagic conjunctivitis, fever			High	Moderate
Hepatitis A virus	Infectious hepatitis	15–50 days	1 week to several months	High	Moderate
Hepatitis E virus	Hepatitis	15–65 days	1 week to several months	High	Moderate
Norovirus	Epidemic vomiting and diarrhea	1–3 days	1–3 days	High	Moderate
Reovirus	Respiratory illness			Moderate	Moderate
Rotavirus	Diarrhea, vomiting	1–3 days	3–7 days	High	Moderate
Sapoviruses	Gastroenteritis			High	Moderate

^aHealth significance relates to the severity of impact, including association with outbreaks.

^bWhen the infective stage is freely suspended in water treated at conventional doses and contact times and pH between 7 and 8. Low means 99% inactivation at 20°C generally in < 1 min, moderate 1–30 min and high > 30 min. It should be noted that organisms that survive and grow in biofilms, such as Legionella and mycobacteria, will be protected from chlorination.

Modified from Yates, M. V. (editor in chief) (2016). Manual of Environmental Microbiology, 4th ed. American Society for Microbiology, Washington, DC. 1088 pp.