STUNG

Af­ter dengue and chikun­gunya, the Aedesa­e­gypti mos­quito de­liv­ers a new shock, Zika fever

Down to Earth - - FRONT PAGE -

DOWN TO EARTH

The world is in the throes of yet an­other in­fec­tious dis­ease out­break. A re­port re­leased by the World Health Or­ga­ni­za­tion ( who) on Fe­bru­ary 5 says that the Zika virus has spread to 33 coun­tries. Brazil, the worst af­fected , has be­tween 0.5 mil­lion to 1.5 mil­lion sus­pected cases.

Zika was first iso­lated from the rhe­sus mon­key in Uganda’s Zika for­est in 1947 and in hu­mans in 1952. But in the next five decades only 15 cases were re­ported from Africa and South­east Asia. In 2007, there was a mas­sive spread of this zoonotic dis­ease (in­fec­tions that emerge in an­i­mals and jump to hu­mans) in Yap, an is­land group in the Western Pa­cific, and things have been get­ting worse since then. The virus went to other Pa­cific Is­lands be­fore reach­ing Brazil, from where it spread rapidly to other parts of South Amer­ica, Cen­tral Amer­ica, Mex­ico, and the Caribbean. Things came to a head on Fe­bru­ary 1 when the huge num­ber of cases forced who to de­clare it a Pub­lic Health Emer­gency of In­ter­na­tional Con­cern. This is only the fourth time who has de­clared a state of emer­gency.

The Zika virus, spread by Aedes ae­gypti and Aedes al­bopic­tus mos­qui­toes, usu­ally causes mild fever, aches, rashes and con­junc­tivi­tis. But this time, the in­ci­dence of mi­cro­cephaly (a con­di­tion of un­der­de­vel­oped heads and brain de­fects) in chil­dren born to women who suf­fered from the in­fec­tion dur­ing preg­nancy is much higher. Till Jan­uary 22, the virus had caused 3,893 sus­pected cases of mi­cro­cephaly only in Brazil. This is over 30 times the num­ber of sus­pected cases re­ported by the coun­try in any given year since 2010. Seven of the 33 Zika-af­fected coun­tries have re­ported a rise in cases of mi­cro­cephaly. The virus also seems to have a link with Guil­lain-Barré Syn­drome, a pro­gres­sive neu­ro­log­i­cal dis­ease that causes paral­y­sis.

The pos­si­ble links have turned the Zika virus from a mild threat to an alarm­ing one. In the Amer­i­cas, the virus has spread rapidly mainly be­cause the pop­u­la­tion has never been ex­posed to this pathogen and has, there­fore, not de­vel­oped im­mu­nity. Only two coun­tries in the Amer­i­cas—Canada and Chile—are com­pletely free of the virus.

A baby is di­ag­nosed with mi­cro­cephaly in Re­cife, Brazil. The neu­ro­log­i­cal dis­or­der is as­so­ci­ated with Zika

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