Zika Virus Dis­ease: A new dis­ease in an ‘im­muno­log­i­cally naïve’ pop­u­la­tion

The Star (St. Lucia) - - LOCAL -

Zika virus dis­ease is gen­er­ally a mild vi­ral dis­ease caused by the bite of an in­fected Aedes ae­gypti mos­quito. Only 1 out of ev­ery 4 per­sons af­fected with the dis­ease may de­velop symp­toms such as fever, skin rash, joint or mus­cle pain, and red eyes. Though the mos­quito is the main agent re­spon­si­ble for spread­ing the dis­ease, it has also been shown that the virus can sur­vive for many weeks in the se­men of in­fected males, mak­ing sex­ual trans­mis­sion of Zika virus dis­ease pos­si­ble.

Prior to 2016, Zika virus dis­ease had not been de­tected in Saint Lucia and most Caribbean coun­tries. This means that our pop­u­la­tion has no nat­u­ral im­mu­nity to this dis­ease. (We are an ‘im­muno­log­i­cally naive’ pop­u­la­tion.) As such, if a per­son is bit­ten by a mos­quito in­fected with the Zika virus, there is a high pos­si­bil­ity that the in­di­vid­ual would con­tract the dis­ease, though its symp­toms may be ab­sent or very mild. Given the very mild na­ture of the dis­ease, most per­sons who con­tract Zika may not know that they are in­fected and would there­fore not be recorded as cases within the health sys­tem. This, in ad­di­tion to lab­o­ra­tory fac­tors, im­plies that the num­ber of con­firmed cases recorded by the Epi­demi­ol­ogy Unit will not re­flect the ac­tual num­ber of cases of Zika virus dis­ease on-is­land. As of June 15, 2016, 8 cases of Zika virus dis­ease have been con­firmed and, of this num­ber, 3 are preg­nant women. These women are be­ing closely mon­i­tored by Ob­stet­ric and Gy­nae­col­ogy spe­cial­ists.

We have also noted a mild but grad­ual in­crease in the num­ber of per­sons pre­sent­ing to health cen­tres and primary care clin­ics with com­plaints of itchy, gen­er­al­ized rash, mainly on their face and up­per body. Some of these in­di­vid­u­als give a re­cent his­tory of hav­ing had a low grade fever but most do not have fever at the time when they seek care for the itchy rash. A few per­sons present with red eyes and in com­par­i­son with the trends seen dur­ing the Chikun­gunya out­break, rel­a­tively few per­sons present with com­plaints of painful, swollen joints.

Rapid lab­o­ra­tory tests for Zika virus dis­ease are un­re­li­able. In ad­di­tion, the virus is de­tectable in the blood of in­fected per­sons for only a brief pe­riod. This makes con­fir­ma­tion of the dis­ease dif­fi­cult. Treat­ment of pa­tients is the same re­gard­less of whether the dis­ease is sus­pected or con­firmed. Treat­ment is mostly sup­port­ive with pain- and fever-reliev­ing medicines such as parac­eta­mol, rest, flu­ids and med­i­ca­tion to de­crease itch­i­ness of the rash where present.

Given that Zika virus dis­ease has been con­firmed in Saint Lucia, as per es­tab­lished epi­demi­o­logic guide­lines only a small sam­ple of per­sons sus­pected as hav­ing the dis­ease will now be rou­tinely tested. All preg­nant women sus­pected of hav­ing Zika virus dis­ease will be tested and closely mon­i­tored dur­ing their preg­nancy, given the pos­si­bil­ity of birth de­fects such as mi­cro­cephaly in their new­borns. Ad­mit­ted pa­tients and pa­tients sus­pected of hav­ing the rare com­pli­ca­tion of Guil­lain Barre Syn­drome (GBS) - a par­a­lytic-like ill­ness - will also be tested. Sam­ples are cur­rently be­ing sent to CARPHA in Trinidad where more ad­vanced, DNA PCR tests are per­formed. We have also sent sam­ples of sus­pected Guil­lain Barre Syn­drome pa­tients to Mar­tinique for test­ing but re­sults have been neg­a­tive for Zika virus dis­ease.

With the on­set of the rainy sea­son and the in­creased re­ten­tion of rain­wa­ter in re­cep­ta­cles such as open drums, dis­carded tyres and other refuse, it is an­tic­i­pated that the mos­quito pop­u­la­tion will in­crease and cause more spread of dis­ease, un­less we take mea­sures to de­crease mos­quito breed­ing and pro­tect our­selves from mos­quito bites.

The mea­sures to be taken to pre­vent the spread of Zika virus dis­ease are the same mea­sures taken to de­crease the spread of other mos­quito-borne dis­eases such as Dengue fever and Chikun­gunya fever. They in­clude: • Wear­ing long-sleeved cloth­ing and long pants • Us­ing mos­quito re­pel­lents on ex­posed limbs and on cloth­ing • Uti­liz­ing bed nets and in­stalling win­dow and door screens where pos­si­ble • Get­ting rid of all breed­ing sites of mos­qui­toes such as old tyres, plas­tics and other refuse around the home; us­ing soil in­stead of wa­ter in flower vases; en­sur­ing that drums are prop­erly cov­ered and wa­ter tanks are prop­erly sealed • Per­form­ing at least once weekly in­spec­tions of your home and sur­round­ings, work­places and schools, to en­sure that there are no breed­ing sites for the Aedes ae­gypti mos­quito.

The Min­istry con­tin­ues its fog­ging op­er­a­tions and mos­quito sur­veil­lance, as well as health pro­mo­tion ac­tiv­i­ties to de­crease the im­pact of Zika and other mos­quito-borne dis­eases.

With the upcoming car­ni­val sea­son, vis­i­tors to our shores are re­minded that mosquito­borne dis­eases are en­demic in the trop­ics and, as such, mea­sures should be taken to pre­vent one­self from be­ing bit­ten by mos­qui­toes. The World Health Or­ga­ni­za­tion also ad­vises that preg­nant women consider de­lay­ing travel to Zika-af­fected areas.

The Min­istry of Health has en­gaged with mul­ti­ple stake­hold­ers in rais­ing aware­ness about Zika virus dis­ease and tak­ing mea­sures to de­crease the breed­ing of mos­qui­toes. Part­ners such as the Tourism Industry, Ed­u­ca­tion sec­tor, com­mu­ni­ties and other stake­hold­ers are en­cour­aged to re­main vig­i­lant and con­tinue pre­vi­ously ini­ti­ated ac­tiv­i­ties within their sec­tors.

The gen­eral pub­lic is en­cour­aged to con­tinue tak­ing mea­sures to pre­vent the breed­ing of mos­qui­toes and de­crease their chances of be­com­ing in­fected with Zika virus dis­ease.

Preven­tion is still the best cure against the Zika virus and the Min­istry of Health con­tin­ues to urge cit­i­zens to keep their sur­round­ings mos­quito-free.

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