Test results need to be interpreted carefully to account for any history of enteric fever, typhoid vaccination, and the general level of antibodies in the populations in endemic areas of the world.

Other means of diagnosing Salmonella typhi (and paratyphi) include cultures of blood, urine and faeces.

These organisms produce H2S from thiosulfate and can be identified easily on differential media such as bismuth sulfite agar.

This differentiation of antibody classes is important as it allows for the distinction of a recent (IgM) from an old infection (IgG).

A single Widal test is of little clinical relevance especially in endemic areas such as Indian subcontinent, Africa and South-east Asia.