Fight­ing Zika with mu­tant mos­qui­tos? Brazil tries new method

The Myanmar Times - - The Pulse -

SCI­EN­TISTS in Brazil are pre­par­ing to re­lease mil­lions of fac­tory-bred mos­qui­toes in an at­tempt to wipe out their dis­tant cousins that carry trop­i­cal dis­eases. The in­sects’ method: have sex and then die.

Bri­tish firm Ox­itec says its ge­net­i­cally mod­i­fied mos­qui­toes will swarm in among or­di­nary species such as Aedes ae­gypti, the in­sect that car­ries feared dis­eases such as Zika, dengue, yel­low fever and chikun­gunya. In late Oc­to­ber, Myan­mar’s gov­ern­ment an­nounced the first known di­ag­no­sis of a case of Zika in Myan­mar, where Aedes ae­gypti are com­mon­place.

The mu­tated ver­sions will mate with the fe­males of the or­di­nary mos­qui­toes, spawn­ing ba­bies with a ge­net­i­cally in­built flaw that causes them to die quickly.

With their work done, the mod­i­fied fa­ther mos­qui­toes will then give up the ghost them­selves – as they are ge­net­i­cally pro­grammed to do.

Ox­itec says its fac­tory in the town of Piraci­caba, north­west of Sao Paulo, can pro­duce 60 mil­lion mu­tant mos­qui­toes a week.

Piraci­caba is the world’s “first and big­gest fac­tory” of ge­net­i­cally mod­i­fied mos­qui­tos, said Ox­itec pres­i­dent Ha­dyn Parry.

“This is the only place where we have a fac­tory like this. We can use this as a hub for Brazil,” said Parry, who trav­eled to Piraci­caba for the plant open­ing.

Cur­rently their only Brazil­ian cus­tomer is the city of Piraci­caba, “but we are hav­ing con­ver­sa­tions with sev­eral mu­nic­i­pal­i­ties and states”, Parry said.

Ac­cord­ing to the firm, five field tests that they con­ducted be­tween 2011 and 2014 – in Panama and the Cay­man Is­lands, as well as the north­east­ern Brazil­ian state of Bahia – showed the pop­u­la­tion of wild Aedes ae­gypti in­sects dropped by 90 per­cent af­ter the mu­tant mos­qui­toes were re­leased.

Ox­itec does not yet have a sales per­mit from Brazil’s An­visa health au­thor­i­ties, and there are no epi­demi­o­log­i­cal stud­ies show­ing whether mos­quito-car­ried dis­eases drop af­ter the fac­tory-bred in­sects are re­leased.

Parry is not con­cerned. “We are still wait­ing for An­visa ap­proval – we have no date for it, but we ex­pect it for 2017,” he said.

And none of this has stopped the mayor of Piraci­caba from sign­ing a four-year, US$1.1 mil­lion deal with Ox­itec.

In its first wave, the com­pany will re­lease 10 mil­lion fac­tory-bred mos­qui­tos each week into this city of 360,000 peo­ple.

The need for in­sect con­trol is press­ing, as the summer in the south­ern hemi­sphere ap­proaches and the mos­quito pop­u­la­tion – and cases of the dis­eases that they carry – is likely to boom.

As of July nearly 1.4 mil­lion cases of dengue were recorded in Brazil, fol­low­ing the record 1.6 mil­lion cases in 2015, ac­cord­ing to health min­istry fig­ures.

In the same pe­riod 174,000 cases of Zika were re­ported.

The Zika virus out­break be­gan in late 2015 in Brazil and has since spread across the Amer­i­cas.

Zika is par­tic­u­larly dan­ger­ous to preg­nant women be­cause it can cause birth de­fects such as mi­cro­cephaly, in which ba­bies are born with un­usu­ally small heads and brain de­for­mi­ties.

Zika in­fec­tion has also been linked to a nerve and im­mune dis­or­der called Guil­lain-Barre syn­drome.

Sci­en­tists keep the spa­cious rooms at the Piraci­caba fac­tory at tem­per­a­ture and hu­mid­ity lev­els ideal for mos­quito breed­ing.

While fe­male mos­qui­toes are kept for breed­ing, male mos­qui­toes of the OX513A breed – espe­cially de­vel­oped by Ox­itec in 2002 – are re­leased to mate with fe­males in the wild, pro­duce short-lived off­spring, then die.

Ox­itec bi­ol­o­gist Karla Te­pedino dis­misses en­vi­ron­men­tal­ists’ con­cerns about the lack of long-term im­pact stud­ies.

“There are three es­sen­tial fac­tors for the trans­mis­sion of these dis­eases: the mos­qui­toes, the virus and hu­mans. What we do here is elim­i­nate the mos­qui­toes, which trans­mit the virus,” Te­pedino told AFP.

“Elim­i­nat­ing the vec­tor, we elim­i­nate the dis­ease,” she said.

The Aedes ae­gypti mos­quito is well-adapted to city life as it can breed in even tiny amounts of wa­ter, such as a pud­dle of rain­wa­ter or wa­ter pooled in flow­er­pots. –

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