India fights to track rise of dengue fever

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iol scitech sept 15 mosquito INDEPENDENT NEWSPAPERS New research explains mosquitoes' apparent selectivity. Picture: Karen Sandison

New Delhi - When the monsoon season ends in India, locals breathe a sigh of relief as the pools of standing water dry up, and the mosquitoes lose their breeding grounds.

This season's official tally of people who fell ill with dengue fever, transmitted by the Aedes aegypti mosquito, was the highest for years at more than 37,000, with 227 recorded fatalities.

But experts say the figures could belie a much higher count, as many cases go undetected or unrecorded.

US-based dengue specialist Scott Halstead says dengue probably strikes at least 1 million Indians per year, extrapolating from data in Thailand and Vietnam, where 0.1 per cent of the population is estimated to catch the disease in any given year.

Even assuming a similar rate to nearby Sri Lanka or Indonesia, both reporting cases in 0.05 percent of the population each year, would put India's real rate above half a million cases annually.

“The government is not making any serious efforts to calculate the true number of people infected,” says Halstead, an adjunct professor in the Department of Preventive Medicine and Biometrics at the McMaster University in Rockville, Maryland.

Authorities say they are taking the problem seriously.

“We agree that there is under-reporting, but we are not in denial mode,” says Dr AC Dhariwal, director of the National Vector Borne Disease Control Programme.

“Our statistics are significant as they crucially show the trends, that dengue is on the increase.”

But “calculating the true extent of the illness is a challenge,”

says Manish Kakkar, head of zoonotic diseases at the Public Health Foundation of India and a member of the World Health Organisation (WHO) expert group on dengue.

Sufferers of the disease's flu-like symptoms seldom seek medical care, while many who do are treated as outpatients and not tested for dengue.

Regulations requiring all suspected dengue cases to be tested and logged are routinely ignored by private clinics, while in public hospitals the tests are “rarely carried out due to the number of patients,” a doctor at a public hospital in Calcutta explains.

Whatever the figure, no one is denying the rise of dengue, which the WHO has classed as a neglected tropical disease - one that causes widespread harm but has largely fallen out of the public consciousness.

Due to the underreporting, communities have no real sense of the danger, even though people are in theory aware of dengue, Kakkar says.

“Constant efforts are not made to prevent mosquitoes from breeding in houses and gardens,” he says. The water in a single flower vase left for a day or two can allow larvae to hatch, he points out.

The cost is often higher than a few weeks in bed.

The family of Balbir Singh Bhati, a farmer on the outskirts south-east Delhi, did not suspect he had dengue when he fell ill in October until it was too late.

“We thought it was a fever that would go away with antibiotics and medicines,” says his 21-year-old son Mohit, who is now looking for work to support his mother and sister. “We are shocked that he passed away so suddenly.”

Once infected, patients can only be treated for symptoms, as the pathogen itself is a virus and therefore not affected by medication.

“Even doctors prescribe juice of raw papaya leaves as there is no (medical) cure,” says a 45-year old business executive in Gurgaon, south-west of the capital. “That has worked for me and for others.”

Another characteristic of the disease is that India's growing population of former sufferers are at higher risk from re-infection.

A second infection by another of the four strains of the disease can prompt the body's immune system to overreact, leading to breathing difficulties, shock and internal bleeding, and much higher hospitalisation and mortality rates than with the first infection, Halstead explains.

With a first vaccine still in development, and only promising limited protection, experts are calling for the fight to be taken to the source of infection. “We desperately need governmental action against the mosquitoes,” Halstead says.

Improvements are also necessary in tracking the disease effectively, he says, citing Brazil as a positive example.

“They have a very sophisticated system for recording dengue cases. India could learn an excellent lesson from it.”

Dhariwal says improvements are in the works.

“Under the Integrated Disease Surveillance Programme, all health facilities including the private sector will have to report the cases,” he says.

“We are putting in the framework to collect the info, including penalties, and by next year, the system should be in place.” - Sapa-dpa

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