Enteric fever is a life-threatening illness caused by infection with the bacteria Salmonella. Serotype Typhi (S. typhi), usually transmitted through food and drinks contaminated with faecal matter. It is associated with symptoms that include high fever, fatigue, headache, abdominal pain, diarrhoea or constipation, weight loss, and a rash known as "rose spots." Early diagnosis and treatment are important because serious complications, including severe intestinal bleeding or perforation, can develop within a few weeks.
Widal test is a presumptive serological test for enteric fever whereby bacteria causing typhoid fever are mixed with serum containing specific antibodies obtained from an infected individual.
Typhidot is a medical test consisting of a dot ELISA kit that detects IgM and IgG antibodies against Salmonella typhi. The typhidot test becomes positive within 2-3 days of infection and separately identifies IgM and IgG antibodies.
The Widal test is positive if TO antigen titre is more than 1:160 in an active infection, or if TH antigen titre is more than 1:160 in past infection or in immunized persons. A single Widal test is of little clinical relevance due to the number of cross reacting infections, including malaria. If no other tests (either bacteriologic culture or more specific serology) are available, a fourfold increase in the titre (e.g., from 1:40 to 1:160) in the course of the infection, or a conversion from an IgM reaction to an IgG reaction of at least the same titre, would be consistent with a typhoid infection.