12-year-old die of dengue fever in Howrah, toll rises to seven in West Bengal

Kolkata: The dengue toll has risen to seven in West Bengal amid experts cautioning against a viral strain triggering hyper-active immune response, an official said on Wednesday.

"The total number of deaths due to dengue is seven since June-end. We have confirmed the death of a 12-year-old child from Howrah due to dengue. A total of 995 people have been affected by the disease since January 2016 in the state," Director of state`s health services B.R. Satpathi said.

Experts say this time a considerable number of patients complaining of typical dengue symptoms (joint pain, rashes etc.) have, however, failed the dengue screening that establishes the mosquito-borne viral disease.

"A lot of people are exhibiting typical dengue symptoms but tests do not reveal dengue," said protozoologist Amitabh Nandy.

Expert Shyamasish Banerjee said the strain that is prevalent this year is triggering an abnormal immune response.

"Liver affection is more than last time and we are observing more inflammation in the gall bladder etc. Also, people don`t know about this but this time, we are also seeing macrophage activation syndrome (MAS) due to the particular strain that is circulating," said Banerjee.

MAS leads to hyper-activated but dysregulated immune activity causing overwhelming inflammatory response resulting in non-remitting high fever, inflammation of spleen, liver ad nervous system dysfunction as well as haemorrhage.

Four different strains of the dengue virus are responsible for the disease: DENV1, DENV2, DENV3 and DENV4.

"In 2014, in Bengal the DENV1 and DENV3 strains were mainly prevalent. In 2015, we saw the more fatal DENV2 and DENV4. We are yet to establish which of the four is circulating now. It will take some time," added Satpathi.