How West Bengal plans to counter a shift in dengue strain

Health and family welfare departmentt alerts district magistrates, focuses on slums as new serotype takes centre stage

By Moushumi Basu
Published: Friday 23 November 2018
As Kolkata counters dengue deaths WB health & family welfare dept take a slew of steps. Credit: Getty Images

West Bengal’s Department of Health and Family Welfare has drawn up a plan to counter a dengue outbreak in the state that has already claimed 22 lives in capital Kolkata. What has added to the department’s worry is that the strain of virus that has affected the most this year is not the usual one.

The National Institute of Cholera and Enteric Diseases, Kolkata tested blood samples of around 700 patients and found that more than 70 per cent were affected by serotype 2 of the dengue virus.

This is the second year when that strain has been predominant. “The pattern of dengue virus is changing. Serotypes 1 and 3 were the most common until about two years ago,” said Ajay Chakraborty, director of health services in the state.

The department has classified the state’s districts into three groups based on their vulnerability to the disease. At a meeting Thursday it directed the district magistrates (DM) to draw up specific plans according to the susceptibility of their respective areas.

Weekly epidemiological and entomological surveillance would feature parameters including mosquito index, larvae breeding, cases of fever, etc, Chakraborty said.

According to him, urban slums would be especially monitored as they draw a large migrant population and have little civic amenities: “The preponderance of the disease is likely to be more in these localities.”

The DMs were asked to form rapid action teams at district, block and municipal levels to cut delay in detecting cases.

Door-to-door surveys have been intensified to identify pools of stagnant water that are ideal breeding grounds for Aedes Aegypti mosquitoes, vectors for the disease. Health department workers were scouting for cases of fever to get patients tested, Chakraborty said.

“We are also re-working our information, education and communication strategies to increase awareness,” he added.

The Kolkata Municipal Corporation has five dengue detection centres. The state also has 32 sentinel surveillance hospital laboratories to collect specialised data on particular diseases. Doctors and para-medics at such centres were being trained to better manage the situation, Chakraborty said.

The prevalent Serotype 2 of the dengue virus is more virulent than others in terms of symptoms as well as mortality. In advanced stages the disease can lead to leakeage of plasma from blood vessels into surrounding tissues. Complications can develop even after the initial fever subsides, said virologist Amitabha Nandy.

He said the change in trend was worrying but serotype classification in itself wouldn’t be of much help as there was no specific medicine for the disease itself.

“What is really important is to carry out requisite confirmatory tests when the initial symptom of fever is detected,” he added.

Pointing out that a number of diseases like malaria and chikungunya may start with fever, he said a timely NS1 (Non-structural protein) test could detect cases of dengue.

Alternative Medicine Specialist and activist Jagannath Chatterjee from Odisha stressed on the importance of herbal medication like Kalmegh (Andrograthis Paniculata) that has been claimed to be effective in treatment as well as prevention of dengue.

According to some research, the herb has the potential to be an anti-viral for dengue. The Tamil Nadu Government has distributed a herbal concoction based on it free of cost to manage dengue. It was also reportedly effective for Zika, chikungunya and similar vector-borne diseases.

Environmental changes may also have a part to play, said agricultural scientist Anupam Paul. He pointed out how species like the Indian Bull Frog (Ranatigerina), the common black frog (Bufomelanostic) and native fish like Chaeng, catfish etc, which thrive on mosquito larvae, are increasingly disappearing from water bodies.

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