A VIRUS MORE DEADLY THAN ZIKA? YES, THERE IS

Rift Val­ley fever virus can in­fect a spe­cialised layer of cells around the pla­centa

The East African - - NEWS - By EMILY BUMGAERTNER

A mos­quito-borne virus that causes Rift Val­ley Fever may se­verely in­jure hu­man foe­tuses if con­tracted by moth­ers dur­ing preg­nancy, ac­cord­ing to new re­search.

The mos­quito-borne virus that causes Rift Val­ley Fever may se­verely in­jure hu­man foe­tuses if con­tracted by moth­ers dur­ing preg­nancy, ac­cord­ing to new re­search.

In a study pub­lished last month in the jour­nal Sci­ence Ad­vances, re­searchers used in­fected rats and hu­man foetal tis­sue to dis­cover how the virus tar­gets the pla­centa. Re­sults showed that the virus may be even more dam­ag­ing to foe­tuses than the Zika virus, which set off a global cri­sis in 2015, and left thou­sands of ba­bies in Cen­tral Amer­ica and South Amer­ica with se­vere birth de­fects.

“Zika caught ev­ery­body by sur­prise,” said Amy Hart­man, an in­fec­tious dis­ease spe­cial­ist at the Uni­ver­sity of Pitts­burgh in the US, who led the re­search. “If doctors had known about Zika's birth ef­fects, they could have done a lot more to pro­tect preg­nant women and ba­bies. With Rift Val­ley Fever, we're try­ing to get ahead of the curve.”

Rift Val­ley Fever pri­mar­ily oc­curs in live­stock in sub-sa­ha­ran Africa, where out­breaks cause 90 to 100 per cent of preg­nant cows in a herd to mis­carry or de­liver still­born calves, of­ten a sig­nif­i­cant eco­nomic loss.

But hun­dreds of cases also oc­cur in hu­mans each year, caus­ing flu­like symp­toms and se­vere liver prob­lems. The out­breaks have moved be­yond Africa: In late 2000, an out­break in Saudi Ara­bia in­fected more than 100,000 peo­ple and led to at least 700 deaths, ac­cord­ing to Dr Hart­man. The mos­quito that car­ries the dis­ease is also found in Europe and the Amer­i­cas.

“Cli­mate change can al­ter how emerg­ing in­fec­tious dis­eases will spread,” said Dr Hart­man. “As mos­quito pop­u­la­tions move and change, we have a po­ten­tial for this to spread far be­yond its nor­mal bound­aries.”

There are no vac­cines or treat­ments for Rift Val­ley fever. The World Health Or­gan­i­sa­tion has called the dis­ease a po­ten­tial pub­lic heath emer­gency.

Two cases of in­fected foe­tuses have been doc­u­mented. One in­fant was born with an en­larged liver and spleen, among other symp­toms; the other died within a week. Be­cause the dis­ease can be asymp­to­matic in preg­nant women, many more cases of ab­nor­mal­i­ties and still­births may have been misiden­ti­fied.

Virus in pla­centa

Among rats used in the study, 65 per cent of the pups born to in­fected moth­ers died, com­pared with 25 per cent of pups born from un­in­fected con­trols. Each in­fected mother lost at least one pup, and all of the in­fected moth­ers' off­spring con­tracted the virus.

Preg­nant rats were also more sus­cep­ti­ble to death from Rift Val­ley Fever than non-preg­nant rats.

Most sur­pris­ing to re­searchers, the in­fected moth­ers' pla­cen­tas har­boured more virus than any other tis­sue in the body — more than even the liver, where the virus' dam­age is typ­i­cally ob­served.

“No one in the field recog­nised this be­fore,” said Cyn­thia Mcmillen, a post­doc­toral re­searcher in Dr Hart­man's lab, and one of the study's lead au­thors.

Test­ing on hu­man pla­cen­tal tis­sue re­vealed that, un­like the Zika virus, Rift Val­ley Fever virus has a unique abil­ity to in­fect a spe­cialised layer of cells that sup­ports the re­gion of the pla­centa where nu­tri­ents flow in.

Zika must take the “side roads” into the pla­centa to in­fect a foe­tus, while the Rift Val­ley fever virus can take the “ex­press­way,” Dr Hart­man said.

“The foe­tus is pro­tected from hun­dreds of thou­sands of dan­gers that could af­fect it,” she added. “Only a few mi­crobes can get past, and this is one of them.”

Last week, the Coali­tion for Epi­demic Pre­pared­ness In­no­va­tions launched a call for pro­pos­als to de­velop hu­man vac­cines against Rift Val­ley fever. About $48 mil­lion will fi­nance up to eight projects on Rift Val­ley fever and Chikun­gunya viruses, ac­cord­ing an an­nounce­ment.

“We need more re­search into the epi­demi­ol­ogy — how it causes dis­ease, and how to pre­vent it,” Mcmillen said. “This could spread be­yond where it is found in the Mid­dle East, so aware­ness is sorely needed.”

Zika caught ev­ery­body by sur­prise. With Rift Val­ley fever, we’re try­ing to get ahead of the curve.” Amy Hart­man, Uni­ver­sity of Pitts­burgh

Pic­ture: File

Re­searchers says Rift Val­ley fever may be more dam­ag­ing to foe­tuses than the Zika virus, which set off a global cri­sis in 2015.

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