Typhoid and paratyphoid enteric fever are acute, generalized infections caused by Salmonella typhi and Salmonella paratyphoid respectively.
The main sources of infection are contaminated water or milk and, especially in urban communities, food handlers who are carriers. Their germs are passed in the faeces and urine of infected people. People become infected after eating food or drinking beverages that have been handled by a person who is infected or by drinking water that has been contaminated by sewage containing the bacteria.

Once the bacteria enter the person’s body they multiply and spread from the intestines, into the bloodstream.
The symptoms of typhoid appear 10 to 14 days after infection; they can be mild or severe and include high fever, rose-colored spots on the abdomen and chest, diarrhoea or constipation, and enlargement of the spleen and liver. In untreated patients complications may be numerous, affecting practically every body system, and can even include perforation of the intestine with haemorrhage. Complications account for the mortality rate of 7% to 14%.

The annual incidence of typhoid is estimated to be about 17 million cases worldwide. Typhoid and paratyphoid fevers are common in less-industrialized countries, principally owing to they problem of unsafe drinking water, inadequate sewage disposal and flooding.