Dengue –typhoid co-infection: a study on coexistence of viral and bacterial infection in endemic areas

Background: Acute Febrile illness (AFI) is a common cause of patients seeking healthcare in India, especially between June and September. Co-infections with two or more infectious agents are also becoming a major health problem and the similarity of symptoms further makes accurate clinical diagnosis and treatment difficult without laboratory confirmation. Material and methods: Total 3250 samples were tested for Dengue NS1 and IgM retrospectively from the patients with history of febrile illness between September to November 2015. Out of these, 251 positive Dengue NS1 and/or IgM samples requested for blood culture and/or Rapid Salmonella IgM test were studied for co-infection of Dengue and typhoid fever. Dengue NS1 and IgM antibodies were detected by Dengue NS1 and Dengue IgM antibody capture ELISA test. Diagnosis of Salmonella infection was done by blood culture and Rapid Salmonella IgM immunochromatography test in the laboratory. Result: In total of 251 positive Dengue samples, 9 samples were found co-infected with typhoid fever. 4 patients were blood culture positive and 5 were Rapid Salmonella IgM test positive. Maximum number of dengue positive cases was found in age group 20- 40 y. Conclusion: Acute febrile illnesses are highly prevalent during rainy season in endemic area like India and possibility of Dengue typhoid fever co infection cannot be ruled out. Meticulous history taking, careful clinical examination and right choice of laboratory tests for the diagnosis of these co-infections not only help in timely detection of the disease but also prevent from the fatal outcomes.