The re­turn of yel­low fever

Financial Mirror (Cyprus) - - FRONT PAGE -

Be­fore the hor­rors of the lat­est Ebola out­break in West Africa could even be­gin to fade from our minds, the Zika virus emerged as a ma­jor global health risk, and is now oc­cu­py­ing re­searchers and doc­tors in South Amer­ica, Cen­tral Amer­ica, and the Caribbean. Yet the death toll from an­other virus is ris­ing fast: yel­low fever.

In south­west­ern Africa, An­gola is fac­ing a se­ri­ous yel­low fever epi­demic – its first in 30 years. Since the virus emerged in Luanda, An­gola’s cap­i­tal and most pop­u­lous city, last De­cem­ber, it has killed 293 peo­ple and in­fected a sus­pected 2,267. The virus has now spread to six of the coun­try’s 18 prov­inces. Trav­ellers have taken cases to China, the Demo­cratic Repub­lic of Congo, and Kenya. Namibia and Zam­bia are on high alert.

Yel­low fever virus is trans­mit­ted by Aedes ae­gypti – the same mos­quito that spreads the Zika virus. Symp­toms in­clude fever, mus­cle pain, headache, nau­sea, vom­it­ing, and fa­tigue. At least half of un­treated pa­tients with se­vere cases of yel­low fever die within 10-14 days.

The good news is that, un­like Zika or Ebola, yel­low fever can be con­trolled with an ef­fec­tive vac­cine, which con­fers life­long im­mu­nity within a month of ad­min­is­tra­tion. And, in­deed, vac­ci­na­tion forms the core of An­gola’s Na­tional Re­sponse Plan, ini­ti­ated early this year with the goal of ad­min­is­ter­ing the yel­low fever vac­cine to more than 6.4 mil­lion peo­ple in Luanda Prov­ince. So far, nearly 90% of that target pop­u­la­tion has been vac­ci­nated, thanks largely to the World Health Or­gan­i­sa­tion, the In­ter­na­tional Co­or­di­nat­ing Group for Vac­cine Pro­vi­sion, and other coun­tries, in­clud­ing South Su­dan and Brazil, which to­gether made some 7.35 mil­lion doses of the vac­cine avail­able.

The mass vac­ci­na­tion ef­fort has stemmed the spread of yel­low fever. But to end the out­break, vac­ci­na­tion has to con­tinue not only in Luanda, where an ad­di­tional 1.5 mil­lion are at risk of in­fec­tion, but also en­com­pass other af­fected prov­inces. This will be a ma­jor chal­lenge. ae­gyp­tii mos­qui­toes in the af­fected ar­eas means that the risk of trans­mis­sion re­mains high.

An out­break in a re­gion like Asia, which lacks ex­pe­ri­ence with a yel­low fever epi­demic and has no ca­pac­ity to man­u­fac­ture the vac­cine, would be par­tic­u­larly dif­fi­cult to control. Ac­cord­ing to John P. Woodall, the founder of the dis­ease-alert ser­vice ProMED, if yel­low fever spreads to parts of Asia with the right cli­mate and mos­quito species, hun­dreds of thou­sands could be in­fected (and pos­si­bly die) be­fore vac­cine stocks are de­liv­ered.

The virus also has the po­ten­tial to spread to the Amer­i­cas, which are home to Aedes mos­quito vec­tors that trans­mit not only yel­low fever, but also dengue, Zika, and chikun­gunya. Al­ready, the Pan Amer­i­can Health Or­gan­i­sa­tion has de­clared an epi­demi­o­log­i­cal alert for yel­low fever in Latin Amer­ica.

To help limit yel­low fever’s spread, in­ter­na­tional health reg­u­la­tions re­quire that all trav­ellers to the 34 coun­tries where yel­low fever is en­demic present a vac­ci­na­tion cer­tifi­cate. But the im­ple­men­ta­tion of those reg­u­la­tions de­pends on each coun­try’s ca­pac­ity, and is thus far from per­fect. Al­ready, a to­tal of nine lab­o­ra­tory-con­firmed cases of yel­low fever im­ported from An­gola have been re­ported by the Na­tional IHR Fo­cal Point of China. Re­ports of yel­low fever in­fec­tion in non-im­mu­nised trav­ellers re­turn­ing from a coun­try where vac­ci­na­tion against the dis­ease is manda­tory high­lights the need to re­in­force the im­ple­men­ta­tion of vac­ci­na­tion re­quire­ments.

The WHO is work­ing closely with sev­eral part­ners and the An­golan govern­ment to com­bat the cur­rent out­break. But, as some health ex­perts have pointed out, even more needs to be done. The WHO now must con­vene an emer­gency com­mit­tee to co­or­di­nate a broader in­ter­na­tional re­sponse, mo­bilise funds, and spear­head the rapid scale-up of vac­cine pro­duc­tion, as well as a “stand­ing emer­gency com­mit­tee” ca­pa­ble of ad­dress­ing fu­ture pub­lic-health crises quickly and ef­fec­tively.

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