Circulation of Dengue virus-1 (DENV-1) serotype in Delhi, during 2010–11 after Dengue virus-3 (DENV-3) predominance: A single centre hospital-based study.

ABSTRACT

Background: Delhi, a city in north India, has so far witnessed several reported outbreaks of dengue. Dengue in Delhi from being epidemic is slowly changing towards being endemic and hyper-endemic. Circulating type of the virus is also changing over the years. In the absence of an effective vaccine, dengue prevention to a major extent relies on virological surveillance, and development of effective, locally adapted control programmes. In the present study, we tried to identify the between-year non-epidemic serotype of dengue virus circulating in Delhi, during 2010–11. Methods: Acute-phase samples were collected from the patients attending the Institute of Liver & Biliary Sciences, New Delhi, India. Dengue diagnosis was done using WHO case definitions. All the samples were subjected to Dengue NS1 Ag ELISA and modified nested RT-PCR. Results: A total of 75 acute-phase samples were received, of which 19 (25.3%) were positive for dengue NS1 antigen. Dengue RT-PCR was positive in 14.6% (11/75) samples. All the RT-PCR isolates were of DENV-1 serotype. No case of concomitant infection with more than one serotype was observed. Median age of involvement was 23 yr (range10–86). Maximum number of cases were seen in the age group of 21–30 yr. Male to female ratio was 1.2 1. Maximum number of suspected dengue cases (n=79) was seen during September and October. Conclusions: DENV-1 was circulating in Delhi in the year 2010–11 in non-epidemic period following reported predominance of DENV-3 and co-circulation of all dengue serotypes in the epidemic years 2003, 2006 and 2007.