Molecular analysis of immunoglobulins related to salmonella typhi in pediatric patients

Abstract

Typhoid fever is a systemic infection caused by Salmonella enterica serotype typhi. It is of major concern in tropical regions of the world. Highest episodes of typhoid fever occur in Asia i.e.93%. Early diagnosis of the disease is mandatory to lower the mortality rate associated with it as well as to prevent the emergence of antimicrobial drug resistance by Salmonella typhi. Research work was conducted in Immunology Department of the Children's Hospital, Lahore for the period of one year including a total of 60 patients suspected of having typhoid fever. Serum samples of these patients were tested for Typhidot IgG and IgM antibodies as well as for the antibodies against TO and TH antigens using Widal test. Of the total 60 patients, 10 (16.7%) were positive for both Typhidot IgG and IgM, 16 (26.7%) were positive for Typhidot IgM, 3 (5%) were Positive for Typhidot IgG and 31 (51.66%) were negative for both Typhidot IgG and IgM. Reading the results of Widal test, 8 (13.33%) were positive for Widal TO and TH antigens, 3 (5%) were positive for Widal TO antigen, 19 (31.7%) were positive for Widal TH antigen and 30 (50%) were negative for Widal TO and TH antigens. IgM is positive at the early stage of acute typhoid fever, IgM along with IgG positive means the middle stage of acute illness. The detection of only IgG cannot discriminate between acute and convalescent phases as it can stay in the serum for at least 2 years or more. The Typhidot test is much helpful for the rapid diagnosis of typhoid fever as compared to Widal test which is still being used in some set ups in poor countries, although has become mostly obsolete. By testing the rise of IgM and IgG antibodies against Salmonella typhi, we can detect the infection at early and late stages, respectively.