In 1896 and named after its inventor, Georges-Fernand<unk> , is an indirect agglutination<unk>  for enteric fever or undulant fever whereby bacteria causing typhoid fever is mixed with a serum containing specific antibodies obtained from an infected individual. In cases of Salmonella infection, it is a demonstration of the presence of O-soma false-positive result.<unk>  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. As with all serological<unk> s, the rise in antibody levels needed to perform the diagnosis takes 7–14 days, which limits its applicability in early diagnosis. 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. Typhidot is the other<unk>  used to ascertain the diagnosis of typhoid fever. A new serological<unk>  called the Tubex<unk>  is neither superior nor better performing than the<unk> . Therefore, Tubex<unk>  is not recommended for diagnosis of typhoid fever. 2-mercaptoethanol is often added to the<unk> . This agent more easily denatures the IgM class of antibodies, so if a decrease in the titer is seen after using this agent, it means that the contribution of IgM has been removed leaving the IgG component. This differentiation of antibody classes is important as it allows for the distinction of a recent (IgM) from an old infection (IgG). The<unk>  is positive if TO antigen titer is more than 1:160 in an active infection, or if TH antigen titer is more than 1:160 in past infection or in immunized persons. A single<unk>  is of little clinical relevance especially in endemic areas such as Indian subcontinent, Africa and South-east Asia. This is due to recurrent exposure to the typhoid causing bacteria, immunization and high chances of cross-reaction from infections, such as malaria and non typhoidal salmonella. If no other<unk> s (either bacteriologic culture or more specific serology) are available, a fourfold increase in the titer (e.g., from 1:40 to 1:640) in the course of the infection, or a conversion from an IgM reaction to an IgG reaction of at least the same titer, would be consistent with a typhoid infection.
Widal test
Frei test
Direct agglutination test
Malaria culture
Heterophile antibody test
Lea test
Broth microdilution
Rapid antigen test