Dengue not so deadly this year?

NEW DELHI: Genetic sequencing of dengue virus samples at the Institute of Liver and Biliary Sciences, Vasant Kunj, has shown the presence of multiple strains of the vector-borne infection in the capital — fortunately the relatively less virulent ones are doing the rounds.

The dengue virus Type I, which causes the classic dengue fever, is predominant. Some patients showed the Type III virus, which causes fever without shock.

The two other strains — Type II which causes haemorrhagic fever with shock and Type IV which causes fever with shock or profound shock — haven't been identified in the samples yet.

"We conducted genetic sequencing of 10 virus samples and almost 70% were found to be of Type I. We are in the process of investigating the other samples but initial reports show Type III is also present," said Dr Ekta Gupta, associate professor, at ILBS.

Microbiologists say the presence of multiple strains of the dengue virus is significant as many people already infected with the disease too become susceptible to infection since they are not immune to the different subtypes. The number of cases in the capital has climbed up to 585 but only two deaths have been reported so far.

Gupta said that dengue, which assumed an epidemic form in 1996, followed by outbreaks in 2003, 2005 and 2006 in the capital, has become hyper-endemic (a disease that is constantly present at a high incidence and/or prevalence rate and affects all age-groups equally). Such conditions are prevalent in several South East Asian countries like Thailand, Vietnam and Indonesia, Gupta said, adding, "the frequency of outbreaks and co-circulation of multiple strains of the virus has increased. It could be due to the rapidly growing population, increasing urbanization and lack of an effective vaccine and vector control programmes.

A recent study published in the Journal of Vector Borne Disease on circulation of the dengue virus in the Capital showed the infection more commonly affects the 21-30 age-group. Maximum number of cases were seen during September-October due to post-monsoon collection of water and increased availability of mosquito breeding sites for the aedes aegypti mosquito.

"Since 1996, we have been facing dengue outbreaks periodically. This is partly due to the irresponsible behaviour of civic agencies which start fogging activities only when panic strikes. Why can't they take preventive measures well in advance so that there is less mosquito-breeding," said Dr Navin Dang, consultant microbiologist and director of Dr Dang's Private Limited.