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 |
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