Table 3.

Microbial indicators and pathogenic organisms associated with waterborne diseases and common sources of contamination.

Microorganisms		Diseases	Source	Numbers *
Bacteria	Salmonella enterica subsp. enterica serovar Typhi	Thyphoid fever	Human faeces	0.2–8,000
	Salmonella enterica subsp. enterica serovar Paratyphi	Paratyphoid fever	Human faeces
	Salmonella enterica subsp. enterica serovar Enteritidis and Salmonella enterica subsp. enterica serovar Typhimurium	Salmonellosis/gastroenteritis	Human/animal
	Shigella sp. (Shigella dysenteriae, Shigella flexneri, Shigella boydii, Shigella sonnei)	Dysentery	Human faeces	0.1–1,000
	Vibrio cholera	Cholera	Human faeces
	Vibrio parahaemolyticus	Gastroenteritis	Human/animal
	E. coli (E. coli O:148; O:157; O:124)	Gastroenteritis	Human faeces	106–107
	Campylobacter sp.	Gastroenteritis	Human/animal	104–105
	Clostridium perfringens		Human/animal	6 × 104–8 × 104
	Faecal streptococci		Human/animal	4.7 × 103–4 × 105
	Enterococci		Human/animal
Viruses	Poliovirus	Poliomyelitis	Human faeces	180–500,000
	Rotavirus	Diahorrea, vomiting	Human faeces	400–85,000
	Adenovirus	Gastroenteritis	Human faeces
	Norwalk virus	Diahorrea, vomiting	Human faeces
	Hepatitis A Virus	Hepatitis	Human faeces
Protozoa	Cryptosporidium parvum	Diahorrea		0.1–39
	Entamoeba histolytica	Amoeba dysentery		0.4
	Giardia lamblia cysts	Diahorrea		12.5–20,000

Note: * Numbers of infectious particles in raw sewage. Adapted from Ashbolt and Grabow et al. [45,46].