Aquatic Pollution and Coastal Management

Unit 2 : Sewage and domestic wastes, treatment and reuse

2.4.3.Health Risks
There are a number of strains of bacteria and viruses that are found in raw sewage. Coliform bacteria are excreted by wild and domestic animals and also existing in the human gut. The greater the sewage contamination and exposure of people, the higher is the risk of contracting ear, nose and throat infection and stomach upsets such as gastroenteritis. Faecal streptococci are more closely associated with human sewage and their presence in a sample is believed to be a better indicator of sewage contamination than that of the coliforms. Faecal streptococci can cause illnesses, especially gastroenteritis. Other disease causing agents, which may be present in the sewage, include enteric viruses, Salmonella and the Hepatitis A virus.
Shellfish grown in sewage contaminated waters may cause food poisoning as mussels and oysters accumulate human pathogens through their filter feeding apparatus.