Microbiological, Serological and Molecular Findings of Malaria Co-infections Associated with Typhoid Fever: A Study from Tertiary Care Centre in North India

Malaria and Typhoid co-infections pose a diagnostic challenge, due to high rate of cross reactivity while performing serological tests. With low sensitivity of gold standard tests i.e. blood culture for typhoid and peripheral smear for malaria, it is very difficult to determine actual burden of typhoid and malaria co infections. Hence this study was planned to evaluate and compare various conventional and molecular tests for detection of typhoid Malaria co-infections. A total of 200 samples were collected over a period of 6 months. Diagnosis of typhoid fever was done by using blood culture and Widal test while confirmation of malaria was done by peripheral blood smear (PS) examination, rapid diagnostic test (RDT) and polymerase chain reaction (PCR). Out of 200 suspected patients 70% (140/200) were males and 30% (60/200) were females. The results showed that the prevalence of true co-infection was 0.5% (1/200), using blood culture and peripheral smear. A total of three samples (1.5%) were positive by both Widal and rapid malaria antigen test. PCR for malaria performed on typhoid positive samples to detect asymptomatic malaria co-infection was found to be positive in 2 patients. Co infection rates determined by serology may be due to cross reactivity, however the true co-infections were determined using blood culture peripheral smear and RT PCR. This will help in determining the actual burden of typhoid malaria co-infections in our set up.