A man fogging a mosquito prone area in south west Delhi. Credit: Owais Rashid Hakiem
Primary dengue infections contribute significantly to severe disease burden1, says a study which challenges the assumption that primary infections of the mosquito-borne disease are less severe than secondary infections.
India has the largest number of dengue cases globally but understanding of the correlation between primary and subsequent dengue infections and disease severity remains unclear.
In a muti-institutional collaboration led by the Emory Vaccine Center, USA, and the International Centre for Genetic Engineering and Biotechnology in New Delhi, researchers studied 619 children with confirmed cases of dengue in three tertiary care centres between 2012 and 2018.
The team identified the infecting dengue virus serotype in 65% of patients – infections were seen with dengue virus 1 (DENV-1), DENV-2, DENV-3 and DENV-4. Researchers classified the patients as having primary or secondary infections based on the ratio of dengue-specific plasma IgM and IgG (immunoglobulin M and G, types of antibodies that help fight off infections).
The team found that primary dengue infections accounted for more than half of the total clinical cases (344 of 619), severe dengue cases (112 of 202) and fatalities (5 of 7), suggesting disease severity did not show a significant association with secondary infections. The frequency of severe disease was similar in both types of infection. This trend was consistent across all clinical sites and was not linked to a specific serotype.
The researchers say this emphasizes the need for a dengue vaccine that can be safely used in people who have never been exposed to the virus.
