Effects of pollutants on the aquatic environment

7.9 Typical pathogens

Table 3 lists some of the major pathogens that cause disease to humans and are likely to be found in polluted water.

Table 3  Some of the major pathogens likely to be present in sewage and in faecally polluted streams

Organism type Organism Disease Remarks
Bacteria Vibrio cholerae Cholera Transmitted via sewage and polluted waters in cholera-endemic areas
Salmonella typhi Typhoid fever Common in sewage
Salmonella paratyphi Paratyphoid fever Common in sewage
Salmonella spp. Food poisoning Cause of food poisoning; usually found in contaminated food of animal origin
Shigella spp. Bacillary dysentery Polluted waters are main source of infection
Bacillus anthracis Anthrax Can be found in effluents from tanneries processing hides from infected animals; spores resistant to treatment
Brucella spp. Brucellosis (Malta fever) in humans; contagious abortion in sheep, goats and cattle Normally transmitted by infected milk or by contact
Leptospira icterohaemorrhagiae Leptospirosis (Weil’s disease) Carried by sewer rats; also present in water contaminated by urine from infected animals and humans; can infect through cuts in skin, or intact skin if immersed for a long time
Viruses Poliovirus Poliomyelitis Transmitted by faecal–oral route via contaminated food or water
Hepatitis A virus (HAV) Hepatitis A Transmitted by faecal–oral route via contaminated food or water
Protozoa Entamoeba histolytica Amoebic dysentery Spread by contaminated waters and sludge used as fertiliser; common in warm countries
Giardia lamblia Giardiasis Found in inadequately treated water
Cryptosporidium spp. Cryptosporidiosis Carried by agricultural livestock and infected persons
Helminths Taenia saginata Tapeworms Eggs very resistant, present in sewage sludge and sewage effluents; can be present in contaminated water sources and food
Ascaris lumbricoides Nematode worms Present in sewage effluents and dried sludge used as fertiliser
Schistosoma haematobium, Schistosoma mansoni Bilharzia Carried by water snails in rivers and irrigation ditches contaminated by human waste in specific regions of the world; enter humans by direct penetration of skin