Fi­lar­i­a­sis ques­tions

Stabroek News Sunday - - REGIONAL NEWS -

In a let­ter pub­lished in this news­pa­per on Thurs­day cap­tioned ‘It makes more sense try­ing to sort out the mos­quito prob­lems to erad­i­cate fi­laria’, Dr Mark Devon­ish took the WHO to task over the method used in its cam­paign to elim­i­nate fi­lar­i­a­sis from the coun­try. The agency is cur­rently run­ning a se­ries of ad­ver­tise­ments in the lo­cal press ex­plain­ing the ra­tio­nale of its pro­gramme, and in­form­ing cit­i­zens about the drugs they are be­ing asked to take.

Erad­i­cat­ing ele­phan­ti­a­sis in par­tic­u­lar, which is the form in which the pub­lic will recog­nise fi­lar­i­a­sis, will be wel­comed by every­one, so a let­ter from a health pro­fes­sional sug­gest­ing that the WHO is do­ing the wrong thing to achieve that end could have a counter ef­fect, dis­suad­ing cit­i­zens from com­ply­ing with the re­quest to take the drugs be­ing ad­min­is­tered. The prob­lem is that layper­sons are not in a po­si­tion to judge whether there is merit in Dr Devon­ish’s as­ser­tions or not.

Dr Devon­ish first de­scribes how a mos­quito spreads fi­lar­i­a­sis by bit­ing some­one who is in­fected, and then trans­fers the worms in their lym­phatic sys­tem to some­one else by bit­ing them. Any­one who is in­fected can be treated with fi­la­r­i­cides to kill the worms. That, he writes, sorts the prob­lem. How­ever, he goes on to say that in Guyana, every­one is be­ing given fi­la­r­i­cides whether they are in­fected or not. He claims that this ap­proach lacks med­i­cal ev­i­dence de­spite it be­ing cham­pi­oned by the WHO. “No tri­als have been done on its ef­fec­tive­ness in erad­i­cat­ing fi­lar­i­a­sis,” he as­sev­er­ates.

He goes on to ex­plain how some­one given fi­la­r­i­cide tablets to­day may be pro­tected for a day or two be­fore the tablet is bro­ken down and ex­creted. “What if a mos­quito is to bite that per­son af­ter the tablet is ex­creted?” he asks, and then pro­vides his an­swer: “The fact is that they will get fi­lar­i­a­sis be­cause the tablet is long gone out of their sys­tem. Com­mon sense would dic­tate for this to be ef­fec­tive then all 800,000 pop­u­la­tion of Guyana have to get the fi­lar­i­a­sis tablet regime at the same time hence there may be a lag in po­ten­tially in­fected peo­ple.”

The doc­tor cites the WHO as ar­gu­ing that a cam­paign over a six-year pe­riod can ad­dress this. How­ever, he goes on to re­mark that the cam­paign has been go­ing on world­wide since 2000 with lit­tle suc­cess in erad­i­cat­ing fi­lar­i­a­sis glob­ally. He ex­pressed doubt that such a strat­egy could be suc­cess­ful in de­vel­op­ing coun­tries “with strug­gling health­care sys­tems.”

Per­haps it could be re­marked that the agency did ex­per­i­ment with putting fi­la­r­i­cides in salt a few years ago, which was man­u­fac­tured in Ja­maica for Ja­maicans and Guyanese. The ex­per­i­ment was not a suc­cess, pos­si­bly be­cause here, at least, it was re­garded with sus­pi­cion, and not enough peo­ple bought it.

Dr Devon­ish’s reser­va­tions not­with­stand­ing, it should be noted that the WHO web­site it­self does ac­knowl­edge that the fi­la­r­i­cide tablets given lo­cally have a “lim­ited ef­fect on adult par­a­sites … [although they]… ef­fec­tively re­duce the den­sity of mi­cro­fi­lar­iae in the blood­stream and pre­vent the spread of par­a­sites to mosquitoes.” (Mi­cro­fi­lar­iae are im­ma­ture lar­vae which grow into adults in a per­son’s lym­phatic sys­tem and are what are trans­mit­ted by mosquitoes.)

In ad­di­tion, the agency on its web­site says that at the start of its world­wide cam­paign, “81 coun­tries were con­sid­ered en­demic for lym­phatic fi­lar­i­a­sis. Fur­ther epi­demi­o­log­i­cal data re­viewed since, in­di­cate that pre­ven­tive chemo­ther­apy was not re­quired in 10 coun­tries... The pop­u­la­tion re­quir­ing MDA [Mass Drug Ad­min­is­tra­tion] has de­clined by 36% (499 mil­lion) where in­fec­tion preva­lence has been re­duced be­low elim­i­na­tion thresh­olds.” It then lists 14 coun­tries as hav­ing achieved the elim­i­na­tion of lym­phatic fi­lar­i­a­sis, while seven more are un­der sur­veil­lance to “demon­strate that elim­i­na­tion has been achieved.” It goes on to say that pre­ven­tive MDA is still re­quired in 52 coun­tries.

Prima fa­cie this would ap­pear to cover some of Dr Devon­ish’s larger con­cerns, although whether in the kind of de­tail he would pre­fer is an­other mat­ter. But he did raise an­other is­sue, and that was the side ef­fects of the drugs used. To give one ex­am­ple, he writes that DEC can af­fect the heart and kid­neys, and should not be used on heart pa­tients or by preg­nant and breast­feed­ing women. He asks whether the ad­min­is­trat­ing per­son­nel are re­ally check­ing for these prob­lems be­fore the medicines are given.

Ex­actly what the ex­tent of the dan­ger of the drugs on cer­tain cat­e­gories of per­sons is, has not been made known to the pub­lic by the global health agency, although it may well be that the ad­min­is­ter­ing per­son­nel have been given in­struc­tions about who should not re­ceive doses. It is some­thing that per­haps re­quires some clar­i­fi­ca­tion from the WHO.

As for Dr Devon­ish, his view – as the cap­tion to his let­ter demon­strates – is that we should for­get about tak­ing on the dis­ease, and deal with the mosquitoes. Well, we have been down this road be­fore. It in­volves some­thing more com­plex than just the WHO and the Min­istry of Health dol­ing out fi­la­r­i­cides to the pop­u­la­tion. It will en­com­pass cen­tral and lo­cal gov­ern­ment agen­cies, re­quire or­gan­i­sa­tional and in some places, en­gi­neer­ing skills, con­sis­tent mon­i­tor­ing and con­sid­er­able sources of funding.

The last time that erad­i­ca­tion was suc­cess­fully achieved was af­ter Dr Gigli­oli worked on the erad­i­ca­tion of malaria from first, the coast­land, and sub­se­quently, the in­te­rior. The in­sec­ti­cide he used was DDT, which was sprayed on the canals and other water cour­ses, as well as in houses in the in­te­rior. How­ever, DDT ac­quired an un­savoury rep­u­ta­tion and was banned world­wide, although re­cently there has been some sug­ges­tion it has stood wrongly ac­cused. In ad­di­tion, in Ge­orge­town and its en­vi­rons, at least, if not else­where, the Min­istry of Health en­tered homes to check for stag­nant water, while a more vig­or­ous City Coun­cil than any we know nowa­days man­aged the drains and trenches. In the ru­ral ar­eas, there were so­phis­ti­cated drainage man­age­ment ar­range­ments that in­cluded the sugar in­dus­try. Ex­actly how all of that would be re­pro­duced in this day and age is a mys­tery, although deal­ing with the drainage for all kinds of rea­sons is a de­sir­able end in it­self, as every­one knows.

Every­one would like to see the end of fi­lar­i­a­sis, and if the WHO’s method to elim­i­nate it from our en­vi­ron­ment, in­deed, from the global en­vi­ron­ment, is vi­able, then they should have our un­qual­i­fied sup­port. It is spe­cial­ists in the sci­en­tific and med­i­cal fields who are best placed to know whether there is any sub­stance at all to Dr Devon­ish’s state­ments; it is dif­fi­cult for the pub­lic to de­cide when they lack the in­for­ma­tion to sup­port their views. Clearly the WHO needs to an­swer the let­ter – al­beit out­side the con­text of their ad­ver­tis­ing cam­paign – re­spond­ing to its con­tentions so cit­i­zens have a clear view of why it is nec­es­sary for them to co­op­er­ate.

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