`Pre­dic­tion will never be per­fect'

Down to Earth - - COVER STORY -

Olivier Res­tif, epi­demi­ol­o­gist at the Univer­sity of Cam­bridge, stud­ies the dy­nam­ics of in­fec­tious dis­eases. He spoke to Down­ToEarth on zoonotic dis­eases. Ex­cerpts What chal­lenges do re­searchers in the field of zoonotic dis­eases face? It of­ten takes sev­eral years of painstak­ing field re­search to iden­tify the an­i­mal species that acted as the reser­voir of a par­tic­u­lar dis­ease. In the case of Ebola fever, the virus has been found in apes, bats, ro­dents and more. In each case, it was only in one or a few an­i­mals, mak­ing it very hard to de­cide if th­ese were just anec­do­tal cases or whether we had found the main source of dis­ease. And when you're deal­ing with a deadly virus, re­searchers have to take ex­treme pre­cau­tions to pro­tect them­selves and the peo­ple around them. What are the road­blocks to the ac­cu­rate pre­dic­tion of oc­cur­rence, size or fre­quency of out­breaks? Once an out­break has started, we have epi­demi­o­log­i­cal mod­els to help us pre­dict how much they are go­ing to spread and guide in­ter­ven­tions. How­ever, just like weather fore­cast, they are no­to­ri­ously un­re­li­able in the longer term be­cause we are deal­ing with very com­plex sys­tems: it takes just one per­son get­ting on a plane to start a pan­demic. On a more op­ti­mistic note, we are get­ting much bet­ter at es­ti­mat­ing risk, so we can di­rect pre­ven­ta­tive ef­fort on the re­gions or the an­i­mal species that we have iden­ti­fied as be­ing more "risky", even if we don't know which dis­ease is go­ing to emerge next. Do you fore­see the de­vel­op­ment of such pre­dic­tive ca­pa­bil­i­ties in near fu­ture? Ma­jor in­ter­na­tional pro­grammes are al­ready in place to fill the gaps in our knowl­edge of the chains of trans­mis­sion that can re­sult in zoonotic out­breaks. This in­volves the iden­ti­fi­ca­tion of viruses al­ready pres- ent in wildlife, and a bet­ter un­der­stand­ing of how peo­ple may come in con­tact with those viruses. But pre­dic­tion will never be per­fect, so we must learn from re­cent out­breaks to im­prove the re­sponse. Has there been any no­tice­able change in the fund­ing avail­able in this field af­ter the in­ter­na­tional at­ten­tion the Ebola epi­demic re­ceived last year? For­tu­nately, the fund­ing ef­fort in this area had al­ready in­creased be­fore the lat­est Ebola out­break. But emerg­ing dis­eases, just like cli­mate change or an­tibi­otic re­sis­tance, are global threats that re­quire in­ter­na­tional col­lab­o­ra­tions, and ev­ery coun­try must con­trib­ute. Fund­ing for re­search is im­por­tant, but we ur­gently need to see in­vest­ment in front-line pub­lic health in­fra­struc­ture so that lives can be saved when the next out­break oc­curs. Are we more likely to see mosquito­borne dis­eases like Zika in fu­ture? Th­ese are the dis­eases which we ex­pect would in­crease in re­sponse to cli­mate change. Al­though in­sect vec­tors have been trav­el­ling from trop­i­cal to tem­per­ate re­gions on­board ships and planes for many years, they are now more likely to sur­vive and be­come es­tab­lished in tem­per­ate re­gions as win­ters be­come milder.

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