Mem­bers of the pub­lic should not take things lightly

New Straits Times - - Opinion - The writer is a pro­fes­sor of im­munol­ogy and in­fec­tious dis­eases, and Bio­science In­sti­tute di­rec­tor of Univer­siti Pu­tra Malaysia

IS our strat­egy in con­trol­ling H5N1 in chicken ef­fec­tive? It was nearly 10 years ago when Malaysia last de­tected the highly path­o­genic avian in­fluenza (HPAI) H5N1 in chick­ens.

In the past few weeks, cases of H5N1 have been re­ported in vil­lage chick­ens and game birds in a few dis­tricts in Ke­lan­tan.

This re­sem­bles the first case of H5N1 re­ported in the coun­try in 2004.

How­ever, not much is known about this elu­sive virus.

A study is un­der­way to de­ter­mine

Im­me­di­ate ban­ning of the move­ment of poul­try from the in­fected ar­eas to other places and con­tin­u­ous sur­veil­lance of the oc­cur­rence of new cases of H5N1 should be strictly im­ple­mented.

the ori­gin of the virus and whether the iso­lated viruses from the chick­ens, ex­press re­cep­tors that are im­por­tant for hu­man in­fec­tion.

Based on what we know of pre­vi­ously char­ac­terised H5N1 cases in Malaysia and other coun­tries, the virus is highly con­ta­gious and fa­tal to chick­ens.

It has a lim­ited ca­pa­bil­ity of caus­ing hu­man in­fec­tion un­less they are in close con­tact with the in­fected an­i­mals.

Fur­ther­more, there is no clear ev­i­dence that the virus can cause hu­man-to-hu­man trans­mis­sion, as what was re­ported in the 2009 flu pan­demic or swine flu H1N1 in­fluenza.

How­ever, the pub­lic should not take things lightly, es­pe­cially poul­try farm­ers and per­son­nel who han­dle live and dead chick­ens from the in­fected ar­eas.

They should ex­er­cise ex­treme cau­tion as H5N1 can cause fa­tal in­fec­tion in hu­mans.

A World Health Or­gan­i­sa­tion (WHO) re­port con­firmed 856 cases of H5N1 in­fec­tion in hu­mans have been re­ported from 2003 to this year, with a case fa­tal­ity rate of 53 per cent, the high­est num­ber of cases be­ing in Egypt, In­done­sia and Viet­nam.

It is im­por­tant to note that th­ese are among the few other coun­tries in the world that vac­ci­nate against H5N1 in chick­ens.

Malaysia has vast ex­pe­ri­ence in con­trol­ling out­breaks of zoonotic dis­eases — such as the Ni­pah virus, Ja­panese en­cephali­tis, ra­bies and HPAI — ef­fec­tively.

The best strat­egy to con­trol the dis­ease is strict biose­cu­rity and stamp­ing out of in­fected chick­ens within a 10km ra­dius of in­fected ar­eas.

Im­me­di­ate ban­ning of the move­ment of poul­try from the in­fected ar­eas to other places and con­tin­u­ous sur­veil­lance of the oc­cur­rence of new cases of H5N1 should be im­ple­mented.

Al­though the use of an­tivi­ral drugs to con­trol the virus in chicken is un­com­mon, se­quence anal­y­sis of the re­cently iso­lated H5N1 in­fected chick­ens will let us know whether the virus has de­vel­oped re­sis­tance an­tivi­ral drugs, such as aman­ta­dine and os­eltamivir, that are be­ing used to treat in­fluenza in hu­mans.

Un­like other vi­ral dis­eases, such as the New­cas­tle dis­ease and in­fec­tious bron­chi­tis, where vac­ci­na­tion is part of rou­tine mea­sures, vac­ci­na­tion against H5N1 is an op­tional mea­sure, which should only be con­sid­ered when there is a clear threat of the virus spread­ing and af­fect­ing ma­jor com­mer­cial poul­try farms.

Even in this sit­u­a­tion, vac­ci­na­tions should be pri­ori­tised on ex­pen­sive birds, such as rare ex­otic birds, pure­bred, grand­par­ent stocks and long-lived chick­ens.

The im­ple­men­ta­tion of a vac­ci­na­tion pol­icy may re­strict an­i­mal move­ment, mar­ket­ing and trade of poul­try and poul­try prod­ucts due to the dif­fi­culty in dif­fer­en­ti­at­ing be­tween in­fected and vac­ci­nated birds (Diva). The inability to im­ple­ment Diva and use of poor qual­ity vac­cines will com­pli­cate de­tec­tion of H5N1, in­creas­ing the chance of the virus cir­cu­lat­ing silently and caus­ing pub­lic health con­cerns.

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