Despite Zika virus emergency, proven control using GE mosquitos held up by Brazilian red tape

Aedes mosquito feeding

As the Zika virus epidemic in the Americas spirals into a full-scale international public health emergency, concerns have emerged that an effective solution to mosquito control using genetically engineered insects is being held up in Brazil due to the government’s failure to address a regulatory technicality about marketing the disease-control product. Only today the Brazilian health minister admitted that Brazil is “badly losing” the battle against Zika, with 220,000 troops drafted in to assist with emergency control measures.

The genetic engineering approach uses specially-bred males that seek out and mate with wild females and pass on an added gene that causes the offspring to die before reaching adulthood. Male mosquitoes do not bite, so there is no chance of increasing the pest population or disease transmission. It is also self-limiting because all the gene-spliced insects die, removing one of the traditional fears expressed about genetic engineering technology.

The technology was developed by the British firm Oxitec, which recently released results from a widespread release of its GE mosquitoes in the Brazilian city of Piracicaba, in Sao Paolo state, which successfully protected 5,000 people by dramatically reducing the population of biting mosquitoes. The mosquitoes targeted, Aedes aegypti, also spread dengue fever and chikungunya disease, neither of which have a vaccine or a cure yet available.

Oxitec obtained full consent for commercial release from Brazil’s National Biosafety Committee (CTNBio) in April 2014, and has announced plans to scale up mosquito production facilities to cover 300,000 people in Piracicaba. Unfortunately, Brazil’s health surveillance regulator Anvisa has not yet pronounced on the technicality of how to label Oxitec’s product for marketing purposes, potentially holding up further deployment.

In particular this delay prevents GE mosquito control from being extended to municipalities across the country who are battling the Zika outbreak and other mosquito-borne viruses such as dengue. The company has reportedly been waiting for 20 months for Anvisa’s approval, lost time that could have been spent planning for rapid scale-up to help tackle the crisis.

Asked to comment on the concerns, Glen Slade, Head of Business Development at Oxitec said: “Oxitec has been in regular contact with Anvisa since May 2014 regarding the commercialisation of its solution for Aedes aegypti control. At this time we are waiting for Anvisa to inform us of its decision on the way forward.”

Zika virus appeared only recently in Brazil, first being reported in April 2015. It has been linked with the birth defect microcephaly, where babies are born with small heads and underdeveloped brains. Since the outbreak began, a spike in microcephaly cases has been reported, with totals now over 4,000. Officials in Colombia, Ecuador, El Salvador and Jamaica are so concerned about the spread of the Zika virus that pregnant women have been advised not to travel to these areas, and some have even warned women to delay pregnancy altogether. The U.S. Centers for Disease Control and Prevention has issued travel alerts for 20 countries in the Americas.

Oddly, international media coverage of the crisis has focused on efforts to develop a vaccine – a potential long term solution but one that will take many years to bring about – largely ignoring the rapid control that GE mosquitoes can offer. Media have also reported on the threat to the Rio Olympics, with one expert today even warning pregnant women not to travel to the games, again without mentioning that Oxitec’s approach could very effectively protect a city by reducing mosquito populations quickly.

It is not clear whether or not anti-GMO groups, who oppose disease control using Oxitec’s method, have been effective in putting pressure behind the scenes with the Brazilian government to block releases. Opposition in the country has been muted, likely because of the urgency of the health situation. Similarly the domestic press has reported positively on the first Oxitec project in Piracicaba. The most likely explanation for Anvisa’s delay in approval is simply bureaucratic inertia, it seems.

Conventional control strategies for Aedes aegypti focus on insecticide fogging, spraying large quantities of pesticide into the environment, and in particular inside peoples’ homes, where the mosquito can hide during the day before biting at night. However, control using fogging is becoming limited because of evolving resistance and the difficulty in finding mosquitoes. In contrast, Oxitec’s approach uses male mosquitoes, which effectively seek out females to mate with, thereby offering much higher levels of population control with the mosquitos themselves doing the work rather than pesticide-spraying humans.

Insecticide fogging also kills other insects and pollutes the ecosystem. The GE mosquito approach is entirely pest-specific, in contrast, targeting only the specific mosquito species that is the disease vector. The GE technology is also self-limiting – as soon as releases of GE mosquitoes stop, the sterility gene will quickly die out in the wild population. Aedes aegypti is an invasive species, spreading with human habitation and in dense cities, so reducing its population is highly unlikely to have any significant negative effects on ecosystems.

Perhaps the most important difference between the Oxitec approach and conventional control is that first results show an impressive 90% control of mosquito populations with the GE mosquitos rather than 20-30% with insecticides.

Some environmentalists have linked the Zika crisis to global warming, which could be facilitating the spread of the warm-loving invasive mosquito Aedes aegypti that is the disease vector. The climate campaigner Bill McKibben worried yesterday, in a hard-hitting piece published by the Guardian, that the Zika crisis will mean “residents of the rich world will, inevitably, travel less frequently to the places just beginning to emerge from poverty. The links that speed development will start to wither; even the Olympics, theoretically our showcase of international solidarity, is likely to be a fearful fortnight in Rio this August”.

As McKibben aptly concluded: “A civilization where one can’t safely have a baby is barely a civilization.” Women’s rights campaigners have also harshly criticised the calls on women to delay pregnacy in several countries affected by the Zika virus outbreak: “It’s incredibly naive for a government to ask women to postpone getting pregnant in a context such as Colombia, where more than 50% of pregnancies are unplanned and across the region where sexual violence is prevalent,” Monica Roa, a member of Women’s Link Worldwide group, told the BBC.

Clearly a more effective rapid disease control option is urgently needed – and Brazil may already have a tool available that can offer a quick way to limit the crisis and protect womens’ right to get pregnant without fear that their babies will be born with birth defects due to the spread of Zika.


© Mark Lynas
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