A call to ac­tion

De­spite Zika threat, plan to test ‘ Franken- fly’ re­mains in limbo.

The Star Malaysia - Star2 - - SCIENCE - By JENNY STALE­TOVICH

AT the epi­cen­tre of the Zika out­break in Latin Amer­ica and Brazil, world health of­fi­cials have em­braced a lab- en­gi­neered “Franken­fly” as a po­ten­tial weapon to con­trol a fright­en­ing virus sus­pected of caus­ing hor­rific birth de­fects in new­borns.

But six years af­ter a pi­o­neer­ing test run in Key West in the US was first pro­posed, a plan to de­ploy the ge­net­i­cally mod­i­fied bugs re­mains on in­de­ter­mi­nate hold.

A lab built to pro­duce de­signer males that breed non- vi­able off­spring re­mains shut­tered while the US Food and Drug Ad­min­is­tra­tion ( FDA) con­tin­ues to mull over po­ten­tial en­vi­ron­men­tal im­pacts.

Mean­while, a pe­ti­tion to stop those tri­als in the tiny, up­scale neigh­bor­hood of Key Haven, just out­side of Key West, con­tin­ues to draw sig­na­tures – more than 160,000 so far. Whether the grow­ing con­cern about Zika spread­ing in Florida breaks a seem­ing stale­mate re­mains to be seen.

An FDA spokes­woman said re­cently the agency has so far re­ceived no “ex­plicit” or­ders to fast- track its re­view, even af­ter Pres­i­dent Barack Obama asked for US$ 1.8bil ( RM7.56bil) to fight the virus and ex­pand mos­quito- con­trol pro­grammes.

The agency, said spokes­woman Juli Put­nam, is work­ing as “ex­pe­di­tiously as pos­si­ble”.

But in Brazil, where be­tween 500,000 and 1.5 mil­lion peo­ple are be­lieved to have been in­fected in the last year, of­fi­cials have de­cided they can’t af­ford to wait.

The Aedes ae­gypti mos­quito, which car­ries the virus, thrives in ur­ban trop­i­cal set­tings – like Brazil’s many fave­las. Over the eons, it has de­vel­oped an in­sid­i­ous pref­er­ence to live with hu­mans and spread dis­ease, that make it the “cock­roach of mos­qui­toes”, said Florida In­ter­na­tional Univer­sity ge­neti­cist Matthew DeGen­naro.

Un­like Florida’s na­tive marsh mos­qui­toes, the Aedes ae­gypti evolved to be at­tracted to hu­man odour.

In­creas­ingly, govern­ment of­fi­cials are look­ing to­ward what some have dubbed franken­flies for help. Last week, the World Health Or­ga­ni­za­tion said fog­ging “fol­lowed by the con­trolled re­lease of ge­net­i­cally mod­i­fied mos­qui­toes” is worth con­sid­er­ing.

Florida Keys Mos­quito Con­trol District ex­ec­u­tive di­rec­tor Michael Doyle is headed to Brazil later this month for a con­fer­ence ex­am­in­ing the use of ster­ile in­sects like the kind Ox­itec hopes to breed in the Keys.

For the Bri­tish com­pany, the Brazil­ian out­break may fi­nally set the stage to per­suade scep­ti­cal Keys res­i­dents and fed­eral reg­u­la­tors.

“When chikun­gunya came into the Caribbean two years ago, that should have been a mas­sive wake- up call,” said CEO Haydn Perry. “We just need to get on with it.”

The com­pany has al­ready re­leased mil­lions of mos­qui­toes in tri­als in Brazil and is build­ing a pro­duc­tion plant in the state of Sao Paulo. The plant, lo­cated near Piraci­caba, a city of about 350,000 where six mil­lion mos­qui­toes were re­leased last April to bat­tle an out­break of dengue, should be fin­ished by mid- year.

With the Zika out­break, Perry said the com­pany is now con­sid­er­ing ex­pand­ing it.

“The big­gest ques­tion we have is, are we build­ing ( the plant) big enough?” he said.

Florida, where 21 travel- re­lated cases of Zika had been con­firmed as of Mon­day, has long been at war with the Aedes ae­gypti, mostly con­trol­ling the dis­eases its spread.

Two years ago, chikun­gunya in­fected about a dozen Florid­i­ans and in 2009 Key West bat­tled an out­break of dengue – a pub­lic health threat that first prompted mos­quito man­agers in Mon­roe County to ponder us­ing the ge­net­i­cally mod­i­fied in­sects in the United States.

Faced with the Zika scare, lo­cal mos­quito con­trol of­fi­cials say they’re keep­ing care­ful watch, but so far have no plans to change their ap­proach even as they are get­ting swamped with calls.

In Mi­ami- Dade County, which as of Mon­day had the most Zika cases with seven, mos­quito sea­son tends to start in late spring or early sum­mer when marsh mosquitos, which don’t carry the dis­ease, blow in off marshes or man­groves on the coast.

De­spite this win­ter’s heavy El Nino rains, mos­quito pop­u­la­tions have not risen, said Chalmers Vasquez, the county’s mos­quito con­trol op­er­a­tions man­ager. The district plans to con­tinue fo­cus­ing ef­forts on get­ting home­own­ers, who have mostly been com­plain­ing about mos­qui­toes around drainage ponds and canals, to dump stand­ing wa­ter.

“In peo­ple’s minds, there’s of course a rea­son to be con­cerned about it,” Chalmers said. “We’re try­ing to get the mes­sage out that canals, ditches and man- made lakes and what­ever we have around here has noth­ing to do with this mos­quito.”

The Keys, with its year- round sea­son, takes a more ag­gres­sive ap­proach. In ad­di­tion to a team of in­spec­tors that go door to door daily in search of breed­ing grounds, planes rou­tinely fog.

“What we do on day- to- day op­er­a­tions is what most peo­ple do in an emer­gency sit­u­a­tion,” said Beth Ran­son, spokes­woman for the Florida Keys Mos­quito Con­trol District.

Which is what brought Ox­itec to Florida, where bat­tling mos­qui­toes has earned the district a rep­u­ta­tion for cut­ting edge tech­niques.

Pitched as a safer, more af­ford­able way of bat­tling Aedes ae­gypti, Ox­itec’s en­gi­neered mos­qui­toes work by re­leas­ing males de­signed to pro­duce off­spring with a kil­lswitch, or de­fec­tive gene that kills them.

The off­spring also bear a flo­res­cent marker gene so their lar­vae can be iden­ti­fied when in­spec­tors con­duct mos­quito counts. That al­lows mos­quito con­trol dis­tricts to gauge the progress of the pro­gramme.

The method was first de­vel­oped to bat­tle an out­break of the flesh- eat­ing screw worm – its Latin name trans­late to “eater of man”. The nasty bug mi­grated from South Amer­ica and by the 1930s was feast­ing on cat­tle across the South­east of the US, mount­ing up mil­lions in losses for ranch­ers.

In 1953, a Texas en­to­mol­o­gist who helped the US Army de­velop DDT came up with the idea of ster­il­is­ing male flies with an X- ray ma­chine. Tests con­ducted around the US, in­clud­ing Sani­bel Is­land, showed huge suc­cesses. The flies are still in pro­duc­tion in the US, Mex­ico and Panama.

What Ox­itec is do­ing, said DeGen­naro, who runs Florida In­ter­na­tional Univer­sity’s Mos­quito Ge­net­ics and Be­hav­ior lab, is a “21st cen­tury” ver­sion of that.

Be­cause mos­qui­toes can’t tol­er­ate ra­di­a­tion, Ox­itec ge­net­i­cally en­gi­neered male mos­qui­toes, which don’t bite, to be ster­ile and have a kill switch.

“They don’t bite, they mate with as many fe­males as they can, and then those fe­males don’t re­pro­duce,” DeGen­naro said. “You’re not re­ally in­tro­duc­ing the gene into the en­vi­ron­ment be­cause things are dy­ing.”

The Brazil­ian out­break also raises an­other trou­bling ques­tion: Is the virus or the mos­quito that car­ries it chang­ing?

Un­til last year, Zika was an ob­scure dis­ease named for a for­est in Uganda with symp­toms so mild health of­fi­cials had trou­ble track­ing it.

Then in 2015, an out­break be­gan in Brazil with a new twist: about 4,000 ba­bies were born at the same time with mi­cro­cephaly that of­fi­cials strongly sus­pect was caused by the virus.

They now be­lieve it may also be trans­mit­ted through sex, yet an­other wrin­kle that could com­pli­cate stop­ping its spread.

Re­searchers also fear that Aedes ae­gypti could de­velop a re­sis­tance to in­sec­ti­cides. Other rapid changes are also rais­ing con­cerns: warm­ing tem­per­a­tures have ex­panded the mos­qui­toes zone while global travel and ur­ban­i­sa­tion of the trop­ics has in­creased.

“We’ve just had this huge chikun­gunya out­break that spread through the Caribbean and South Amer­ica. So why should we be so sur­prised that an­other mos­quito- borne ill­ness is do­ing the same thing?” DeGen­naro said. “We have been in­cred­i­bly lucky in Mi­ami. We re­sisted the chikun­gunya out­break. I hope we will re­sist the Zika out­break.”

— Pho­tos: TNS

deGan­naro holds a bot­tle with a mos­quito used in his re­search to help com­bat the Zika virus

A re­searcher holds his arm in a test to watch the mosquitos atr­racted to hu­man scent.

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