Genetically modified mosquito eyed as weapon to control Zika

In Photo: This 2006 photo provided by the Centers for Disease Control and Prevention shows a female Aedes aegypti mosquito in the process of acquiring a blood meal from a human host. On January 15 US health officials are telling pregnant women to avoid travel to Latin America and Caribbean countries with outbreaks of a tropical illness linked to birth defects. The Zika virus is spread through mosquito bites from Aedes aegypti and causes only a mild illness in most people. But there’s been mounting evidence linking the virus to a surge of a rare birth defect in Brazil.

By Makiko Kitamura | Bloomberg

GENETICALLY modified mosquitoes that would help fight the Zika virus are getting urgent attention from US regulators, as global health officials raise alarms about the pathogen’s spread.

The US Food and Drug Administration (FDA) is in the final stages of reviewing an application from Intrexon Corp.’s Oxitec unit to conduct a field trial in the Florida Keys, Oxitec CEO Hadyn Parry said in a phone interview. Parry wasn’t able to provide further details on the timing of an FDA decision.

Oxitec genetically modifies the males in a breed of mosquito known as Aedes aegypti—responsible for transmitting Zika, Dengue, Chikungunya and Yellow Fever—so that their offspring die young. The Zika virus has been spreading “explosively” in South and Central America, the World Health Organization (WHO) said on Thursday. Developing a vaccine could take years, drugmakers and health experts have cautioned.

“In the US, fortunately so far, there isn’t any transmission of the disease, but the question is how long will that situation last?” Parry said. “If it does come in, then you need to be able to act quickly.”

Risk in the US

In the US the risk is that travelers will return from affected countries with the virus in their blood, get bitten by mosquitoes in the US, and transmit the virus locally.

The WHO plans to convene a meeting on February 1 in Geneva to consider whether to declare the outbreak—which ma y be linked to microcephaly, a birth defect that causes brain damage and abnormally small heads—as an international public health emergency. It says the pathogen could infect as many as 4 million people in the Americas this year, based on models from the spread of dengue. In most people, the virus causes mild symptoms such as fever, rash and joint pain.

Gene-modification controversy

Genetically modified animals have not been without controversy. The FDA said on Friday that it would ban the US import of salmon made by AquaBounty Technologies Inc. that have genes added to make them grow faster.

“Mosquitoes are food for lots of animals; We would still want to see studies of when birds and bats and amphibians eat these genetically modified animals,” said Jaydee Hanson, a senior policy analyst at the Center for Food Safety, an environmental advocacy organization based in Washington. “They’re introducing into the ecosystem some genetic constructs that have never been there before.”

Hanson also raised the possibility that other mosquito species could still carry the Zika virus. “It doesn’t solve the problem.”

“You always get some people who say I don’t like genetic engineering because it’s a bad thing and we’re messing with nature,” Parry said, referencing concerns that a modified mosquito could spread and take over from other species. “With ours, it’s the complete opposite—it’s a self-limiting gene, they can’t reproduce.”

Oxitec’s FDA application includes an environmental assessment that will be published for public comment. The regulator will complete its evaluation after reviewing the information with the Centers for Disease Control and Prevention and the Environmental Protection Agency, according to a statement on its web site.

A spokesman for the FDA declined to comment beyond referring to the statement.

Brazil effort

Oxitec, based in the UK in Abingdon, near Oxford, won approval for its mosquito in April 2014 from Brazil’s biosecurity commission and has a factory in Campinas, near Sao Paulo. Last week the company said it’s building a larger facility in Piracicaba, also near São Paulo. Oxitec is awaiting final clearance from the Ministry of Health to authorize the sale of the mosquitoes to local authorities and private operators.

As each female mosquito produces over 500,000 eggs in a month, and they are easily transportable to various regions, scaling up to cover large populations isn’t a challenge, Parry said. “What we’re offering is a tool that is going to be really powerful in reducing these mosquito populations and reducing the threat,” Parry said. “It needs to be accelerated.”

Asian’s sick travelers 

The Zika virus is spreading rapidly in Latin America, and Asian governments have issued advisories in a bid to contain the spread of the disease, which could be linked to birth defects and can cause temporary paralysis. So far, no Zika case has been confirmed anywhere in Asia.

A look at some of the measures announced:

 Malaysia. Health authorities have asked travelers from South and Central America who display symptoms such as fever and rashes to immediately report to
health centers.

Deputy Health Director Dr. Lokman Hakim Sulaiman said the move was imperative as it was not practical to conduct public health screenings at national gateways.

“The virus is difficult to detect and there is no quick point-of-care test which can be used,” he said.

 Japan. Japan’s Foreign Ministry has issued a safety advisory urging women to try to avoid traveling to Brazil and other affected countries during pregnancy, and advised all travelers to the area to use caution. It suggested wearing long sleeves and pants, using mosquito sprays and avoid leaving out buckets, empty gardening pots and other containers that can catch water, and report to medical institutions in case of developing suspected symptoms.

The health authorities asked medical facilities to advise pregnant women not to visit the Zika areas, conduct test on suspected patients returning from the areas and send samples to the national lab.

 Australia. The Department of Foreign Affairs and Trade is advising pregnant women to avoid travel in areas where Zika is active.

The federal government is also asking Australian doctors to look out for signs of Zika infection in travelers returning from affected areas. A spokesman said Australian laboratories could diagnose the virus if required.

 India. Health Minister Shri J. P. Naddahas has stressed the control of the spread of Aedes mosquitoes that transmit dengue and the Zika virus and breed in clean water.

“Community awareness plays an instrumental role in this regard. There is a need for greater awareness amongst community,” he said.

India is also stepping up surveillance and has set up a technical group to monitor the situation.

 Hong Kong. Health officials are advising pregnant women and those planning pregnancy to adopt necessary anti-mosquito precautions, and consider deferring trips to areas with Zika virus transmissions.

Secretary for Food and Health Dr. Ko Wing-man also said that because only up to one quarter of the infected persons might develop relatively mild illness, “the attention was therefore not too big.”

Aedes mosquitoes are currently not found in Hong Kong, the Health Department said, but the secretary said that other species of mosquito present in the territory are also considered as possible carriers of the disease.

• Vietnam. The Vietnamese health authority has warned people coming from countries with the Zika virus to monitor their health for 14 days and if they develop fever to report to medical facilities.

The health authority also warned people to empty water containers and use mosquito nets to prevent the possible spread of the virus.

Image credits: AP


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