A new strain of dengue raises con­cern

This year, there have been more than 19,000 cases of dengue in Tamil Nadu. And doctors and sci­en­tists are on ten­ter­hooks over the emer­gence of a new geno­type of the dengue virus

Governance Now - - CONTENTS - Shivani Chaturvedi shivani@gov­er­nan­cenow.com

In 2012, there was a ma­jor out­break of dengue in Tamil nadu. Across the state, 12,826 cases were re­ported, but the epi­cen­tre was Tirunelveli dis­trict. There were 66 deaths. Bad as this was, it marked a turn­ing point in the course of the dis­ease: early in novem­ber 2017, sci­en­tists at the na­tional in­sti­tute of Virol­ogy (niv) in Pune an­nounced the pres­ence of a new, Asian geno­type of the dengue-caus­ing virus from the sam­ples of the 2012 out­break in Tamil nadu and the 2013 out­break in Ker­ala. This is a cause for worry, as sci­en­tists and physi­cians have no way of pre­dict­ing how the new geno­type will af­fect the stricken and whether it will re­sist old treat­ment pro­to­cols. it will be a game of wait and watch very care­fully.

glob­ally, the widely preva­lent strains of the virus are denv-1, denv-2, denv3 and denv-4. All four have been ac­tive in in­dia, but the dom­i­nant strain has been what is called the Amer­i­canafrican geno­type of denv-1, known to oc­cur in 52 per­cent of serum sam­ples of pa­tients from across in­dia. now, along with the old Amer­i­can-african denv-1 geno­type, a new Asian geno­type na­tive to in­dia has been de­tected. sci­en­tists es­ti­mate that the new geno­type has been around for six decades; but only of late has it caused dengue in suf­fi­ciently large num­bers of pa­tients to be de­tected in sam­ples. And it is not as if the new strain has re­placed the old: the old ex­ists with the new, fur­ther fog­ging doctors’ view of how epi­demics might play out. “Both old and new geno­types of denv-1 are now co-cir­cu­lat­ing in Tamil nadu and Ker­ala,” says dr ra­jan r Patil, se­nior epi­demi­ol­o­gist and as­so­ciate pro­fes­sor at srm univer­sity, chen­nai, who is study­ing how the two geno­types are com­pet­ing for dom­i­nance.

Will the new geno­type cause more out­breaks of the dis­ease? Will the symp­toms be dif­fer­ent, and, more im­por­tantly, more de­bil­i­tat­ing? Will it cause higher mor­tal­ity? Will it cause more out­breaks? Will it cause vari­a­tions in the ex­ist­ing form of the dis­ease? What is the level of epi­demics it will cause? such are the ques­tions sci­en­tists are seek­ing an­swers to. But the main cause of worry stems from the new geno­type hav­ing been as­so­ci­ated with se­vere and ex­ten­sive dengue epi­demics in sin­ga­pore in 2005 and sri Lanka in 2009. in fact, there is rea­son to be­lieve, say sci­en­tists, that the geno­type may have ar­rived in south in­dia from sin­ga­pore.

“The Asian geno­type would have en­tered south in­dia years back, and now, when­ever there is an epi­demic, it spreads very fast,” says dr Arvind ra­manathan, who has worked on dengue in sin­ga­pore for three years and is now based in chen­nai. “even­tu­ally, it might spread across the rest of the coun­try. it is just a mat­ter of time.” He says a re­search pa­per from Viet­nam too men­tioned

“Since there is no vac­cine against dengue, ac­tive sur­veil­lance is the only way out. Gov­ern­ments only want quick so­lu­tions when there are out­breaks, but won’t cre­ate a sys­tem to pre­vent them.” PK Ra­jagopalan Ex direc­tor, Vec­tor Con­trol Re­search Cen­tre, ICMR, Puducherry

that the Asian geno­type virus had been found in pa­tients there and that it was able to pro­duce a larger num­ber of viruses in the blood.

Be­cause of this, the chances of the dis­ease spread­ing are much more. As is well known, the dis­ease is spread chiefly by the Aedes ae­gypti species of mos­quito. if pa­tients have the virus in higher num­bers in their blood, the chances of it spread­ing by mos­quito bite are higher, says dr ra­manathan. “in the rest of the coun­try, it is still the Amer­i­can-african geno­type. But it now seems that in Tamil nadu, the Asian geno­type has all but dis­placed the Amer­i­can-african geno­type,” he adds. This poses a pub­lic health hazard. sin­ga­pore has ded­i­cated teams for dengue that go from house to house to screen peo­ple for the dis­ease and ad­vise treat­ment. “since dengue is a big threat in Tamil nadu now, we should have ded­i­cated teams. We have to work more sys­tem­at­i­cally,” he says.

Ac­tive sur­veil­lance is the only way since there is no vac­cine against the dis­ease, says PK ra­jagopalan, for­mer direc­tor of the Vec­tor con­trol re­search cen­tre, in­dian coun­cil of Med­i­cal re­search, Puducherry. He says the gov­ern­ment’s ap­proach is lack­adaisi­cal; gov­ern­ments want quick so­lu­tions when there are out­breaks, but won’t cre­ate and sus­tain as sys­tem to pre­vent them.

Treat­ment, by and large, re­mains the same, what­ever the geno­type. “The only prob­lem is that since all four strains of dengue are preva­lent, and a new Asian geno­type has also emerged, we need to be ex­tra care­ful and can’t ig­nore even a sim­ple fever,” says J rad­hakr­ish­nan, prin­ci­pal sec­re­tary (health), in the Tamil nadu gov­ern­ment.

in­deed, Tamil nadu has a dengue prob­lem on hand: this year, there have been more than 19,000 cases of dengue, with 52 deaths. (For com­par­i­son, in 2016, there were more than 2,500 cases; the death count was five.) But health depart­ment of­fi­cials and pub­lic health vol­un­teers say un­der­staffing at health cen­tres and hos­pi­tals is one of the ma­jor rea­sons the gov­ern­ment has been un­able to check the spread of the dis­ease.

“We have to go at six o’clock in the morn­ing to su­per­vise anti-lar­val pro­grammes, which is ac­tu­ally the job of health work­ers,” says dr nuzrath Ja­han. she says lo­cal self-gov­ern­ment bod­ies too should take ac­tive part in try­ing to check the spread of the dis­ease. so far, they haven’t taken part in such pro­grammes.

Ameer Khan, na­tional co-con­vener of the Peo­ple’s Health Move­ment of in­dia, says, “nine thou­sand vil­lage health nurses were ap­pointed in the state in the 1980s, and there was ap­point­ment of an equal num­ber of health in­spec­tors at that time. over a pe­riod of time, the gov­ern­ment did not make fresh ap­point­ments of male health in­spec­tors once the ex­ist­ing ones re­tired. so the posts re­mained va­cant and at present there are only 3,000 health in­spec­tors across the state whereas there are more than 10,000 vil­lage health nurses.” He says health in­spec­tors play an im­por­tant role in check­ing the spread of vec­tor-borne dis­eases: they are meant to check ev­ery house for stag­nant wa­ter, anti-mos­quito pre­cau­tions and so on. un­der each pri­mary health cen­tre, there are at least six sub-cen­tres, each of which is sup­posed to have a health in­spec­tor. “But now, there is only one health in­spec­tor to ev­ery pri­mary health cen­tre,” says Khan. “so prac­ti­cally, there are no health inpsec­tors work­ing at the vil­lage level.”

Be­sides, there is no staffing to or­gan­ise med­i­cal camps to di­ag­nose and ed­u­cate peo­ple about prevent­ing vec­tor­borne dis­eases. no won­der, sci­en­tists and doctors are wor­ried about the lat­est dengue out­break.

“Each pri­mary health cen­tre (PHC) has at least six sub-cen­tres, each of which must have a health in­spec­tor. But now there’s only one in­spec­tor to ev­ery PHC.” Ameer Khan Na­tional co-con­vener, Pub­lic Health Move­ment of In­dia

Pri­mary health cen­tres in Tamil Nadu are un­der­staffed, and this comes in the way of check­ing the spread of dengue

Newspapers in English

Newspapers from India

© PressReader. All rights reserved.