Detection of Dengue Viral Infections in Aedes Mosquitoes: An Essential Tool for Epidemiological Surveillance (Commentary)
Dengue fever (DF) and dengue haemorrhagic fever (DHF) are important mosquito-borne viral diseases of humans and recognised as important emerging infectious diseases in the tropics and subtropics. (1) There has been a considerable increase in the geographic spread, number of cases and severity of the disease in the past four decades, since there is a drastic change in the environment due to rapid urbanization and increase in transportation facilities in several parts of India. Thus, the disease once confined to urban areas has now penetrated in to rural areas with several outbreaks from rural areas. As there is no vaccine available for the dengue fever, the prevention and control of the disease mainly depends on the epidemiological surveillance that provides reliable estimate of the disease and thereby helping to implement effective vector control measures. There are several methods such as detection of virus specific IgM antibodies, virus isolation and viral antigen detection available for the diagnosis of the clinical specimens. However, it is important to find out the vector infection rate as well as the density in an area to determine the transmission potential of dengue virus. Identifying serotypes only during outbreaks will not be of much helpful to prevent any future outbreaks. Mapping of areas with prevalence of different serotypes is essential to develop a forecasting system. In India, dengue virus isolations in mosquitoes have been made in wild-caught mosquitoes as early as 1960s (2,3). However, suckling mice inoculation for virus isolation, a laborious and time consuming technique which requires many passages has been replaced by recent techniques such as immunofluorescent assay using serotype specific monoclonal antibodies.