Typhoid fever is a life-threatening disease caused by a bacteria Salmonella Typhi . Salmonella Typhi only lives in humans. People with typhoid fever carry the bacteria in their bloodstream and intestinal tract. Severe cases may lead to serious complications or even death. Fatality rates in typhoid fever range from 1-4% in treated cases and 10-20% in untreated cases. The highest fatality rates are reported in children <4 years of age.