Waterborne and Oral Pathogens: Cholera and Stomach Ulcers

Cholera: spread through water

A pathogen is a microorganism that causes disease. Cholera is caused by bacteria and produces diarrhoea, which can lead to dangerous dehydration. The bacteria can leave an infected person in their faeces. If sewage contaminates a drinking-water supply, another person may swallow the bacteria in that water. Food washed or prepared with unsafe water can also pass on the infection. Poor sanitation makes this chain of transmission more likely.

Prevention works by breaking the chain at different points. Safe disposal and treatment of sewage keep faeces out of water supplies. Providing treated drinking water, or boiling water when a safe supply is unavailable, prevents people swallowing the bacteria. Washing hands with soap after using the toilet and before preparing food reduces transfer to water, food and utensils.

Helicobacter: transmission through the mouth

Helicobacter pylori is a bacterium that can infect the stomach lining. Some infections damage its protective lining and lead to a stomach ulcer, although many infected people do not develop one. Edexcel describes its spread as oral transmission: the bacteria enter a new host through the mouth. Unlike cholera's specified waterborne route, this does not mean every Helicobacter infection comes from drinking water.

The exact ways H. pylori spreads are not fully established. It may pass through contact with an infected person's saliva, for example when food or utensils are shared. Contaminated food or water, and poor hand hygiene after contact with faeces or vomit, may also allow bacteria to reach the mouth. Washing hands after using the toilet and before eating, preparing food hygienically, using safe drinking water and avoiding shared eating utensils can reduce these opportunities for transmission.