Episode of coexisting infections with multiple dengue virus serotypes in central Karnataka, India

Summary: Background: The co-circulation of multiple dengue virus serotypes has been reported in many parts of the world, including India; however, concurrent infection with more than one serotype of dengue virus in the same individual is rarely documented. Method: An outbreak of dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) occurred in and around Davangere, Karnataka, from June 2011–March 2012. This is the first report from India with a high percentage of concurrent infections with different dengue virus serotypes circulating during one outbreak. Acute phase sera from patients were tested for the presence of dengue virus RNA by RT-PCR. Results: Of the 72 samples tested for dengue virus RNA, 42 (58.3%) were positive. All four dengue virus serotypes were found to be co-circulating in this outbreak, and DENV-2 was the predominant serotype. In addition, concurrent infection with more than one dengue virus serotype was identified in 18 (42.9%) dengue virus-positive samples. Conclusion: Our study showed that serotype DEN-2 was dominant in the positive dengue virus-infected samples; the other serotype present was DEN-3. This is the first report of concurrent infections with different dengue virus serotypes in this part of the world. Keywords: Dengue fever, Concurrent infection, RT-PC