Effects of pollutants on the aquatic environment
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# 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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