Dengue outbreak increases with climate change: Dr Nemai Bhattacharya

Climate change and global warming were found to be the most important contributors behind the rise in dengue cases in West Bengal over the years, said Dr Nemai Bhattacharya, Professor and head of the Virology department of The School of Tropical Medicine.

While pointing out the causes as why the disease has been surfacing for repeated times in a year taking a heavy toll on human lives, Bhattacharya said the climate change played an important role here. There had been significant changes in weather in recent times which made dengue-virus stronger gradually. Global warming and a sharp rise in the temperature helped the virus to thrive further. Dengue was never such life threatening like Ebola, Japanese Encephalitis as it now appears to be in recent times, Bhattacharya said.  

The proposition that is doing a round that the disease appearing more than once a year due to a change in the nature of dengue virus was summarily rejected by Bhattacharya. 

For example, it may be mentioned that the dengue first appeared in January 2015 and after claiming several lives, the disease later subsided in April. It again resurfaced in September and killed several people across the state.

There was much hue and cry in the state that it was the failure of the civic bodies as they failed to take adequate preventive measures leading to the death of several people. 

But according to him, it was never easy to anticipate the timing of possible attack of the disease because the changes in weather help the virus to grow. Despite of preventive measures taken up by the civic bodies, the killer mosquitoes continue to sting people. One of the main reasons behind the rise of the disease was the lack of awareness among people, he said.

Bhattacharya, however, stressed the need of anti-dengue campaign at regular interval especially in February-April. 

Entomologists should visit the areas at risk and collect the samples of mosquito larva. Beside the civic bodies, he appealed to all the institutions, both government and private and the households to undertake surveillance and to clean the water in the reservoir and other container from time to time. 

Explaining why the disease is dangerous, he said people were often attacked by dengue twice within a gap of six months or a year.  In these cases, there were high chances of mortality as it has been found that a patient was attacked twice by two different types of dengue viruses within a short span of time. 

In such cases there were “heterotypic infections” or anti-body reactions in the patient’s body leading to deadly hemmaregic dengue or shock syndrome. There are four types of dengue viruses.

Previously, it was found that dengue used to appear during the post-monsoon season and hence the outbreak would have picked up its pace during September-November and later subsided. Taking the example of 2015, Bhattacharya said.