Zika Epi­demic to last for Years, could be­come En­demic

The Star (St. Lucia) - - HEALTH - ZIKA -

The Zika virus isn’t go­ing any­where any­time soon, ac­cord­ing to ex­perts. They say the epi­demic is likely to con­tinue for an­other two to three years, and in a worst-case sce­nario could be­come en­demic in Latin Amer­ica.

Sci­en­tists from the Med­i­cal Re­search Coun­cil Cen­tre for Out­break Anal­y­sis and Mod­el­ing at Im­pe­rial Col­lege Lon­don believe the epi­demic will end only when the pop­u­la­tion reaches a stage of “herd im­mu­nity,” when there are no longer enough un­in­fected peo­ple for trans­mis­sion of the virus to be sus­tained.

Once this stage is reached, there would be a long pe­riod with few new cases un­til the emer­gence of a new gen­er­a­tion who had not been ex­posed to Zika, the re­searchers said in the jour­nal Sci­ence.

Us­ing data mod­el­ing, the sci­en­tists pre­dicted that the next out­break would take place in around 10 years’ time. And they said slow­ing the spread of the virus would sim­ply de­lay the point at which it fiz­zled out nat­u­rally.

Ear­lier this year, the World Health Or­ga­ni­za­tion (WHO) de­clared the Zika virus a global pub­lic health emer­gency, largely be­cause of the risk to new­borns.

Zika in­fec­tion is gen­er­ally mild, with most peo­ple ex­pe­ri­enc­ing few, if any, symp­toms. But it is known to cause mi­cro­cephaly, a se­vere birth de­fect in which ba­bies are born with ab­nor­mally small heads and brain dam­age.

De­spite con­cerns from lead­ing sci­en­tists, the Olympic Games are go­ing ahead next month in Brazil, where the cur­rent out­break that be­gan last year con­tin­ues to rage.

Brazil­ian health work­ers have tried to tar­get the Aedes ae­gypti mos­quito, which trans­mits Zika. But the re­search pa­per said the out­break was not “con­tain­able” and tar­get­ing the mos­quito would have lim­ited im­pact.

Pro­fes­sor Neil Fer­gu­son, lead au­thor of the re­search, said any ef­forts to slow the spread of the virus could ac­tu­ally pro­long the cur­rent epi­demic. In a worst-case sce­nario, he said, the virus could be­come en­demic. “It might also mean that the win­dow be­tween epi­demics could ac­tu­ally get shorter.”

The virus could be­come en­demic in Latin Amer­ica, which would re­sult in smaller, fre­quent out­breaks, for ex­am­ple, but no one yet un­der­stood why Latin Amer­ica was par­tic­u­larly af­fected.

“One pos­si­bil­ity is cli­mate may have in some way aided spread of the virus, as spread co­in­cided with an El Nino event,” Pro­fes­sor Fer­gu­son sug­gested. “Ge­netic mu­ta­tion of the virus might also have played a role, although early data cur­rently give lim­ited sup­port for this hy­poth­e­sis.”

Fer­gu­son also spec­u­lated that pre­vi­ous ex­po­sure to Dengue fever might heighten the Zika in­fec­tion in an in­di­vid­ual, as re­cent stud­ies had sug­gested.

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