Compiled by Yuan-ling Liang

In response to the growing population infected with Zika, many countries are seeking solutions to tackle mosquito-borne diseases. On February 15, Taiwan also announced a research team may be launched to study epidemics due to the widespread of dengue fever in Southern islands and the potential threat of the Zika virus.

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Fighting Zika with genetically modified mosquitoes

British company Oxitec, a subsidiary of the biotech firm Intrexon (XON), has been working to control the spread of mosquito-borne diseases. With scientists from Oxford University, the company focuses on the reproduction of mosquitoes rather than prevention of bites and medical cure. Genetically modified mosquitoes OX513A are bred and introduced into the air to mate with other Aedes aegypti mosquitoes, which force their offspring to die earlier.

Diseases spread by the Aedes aegypti mosquito include Zika virus, dengue fever, chikungunya and yellow fever, which all lead to destructive consequence in human health. Occurring mainly in tropical areas, these diseases put more than an estimated 40% of the world’s population at risk, fatal or not. The recent outbreak of Zika virus has even been recognized as the biggest global health threat since the emergence of Ebola.

CNN reported in 2014 that Oxitec breeds large numbers of mosquitoes in laboratories and injects the sperm cells of the males with a lethal gene to control the spread of dengue fever. When the mosquito is released into the wild and mates with a female — always of the same species – the deadly transgene is passed on and the offspring dies.

According to test results, examinations performed by Oxitec in Malaysia, Brazil, Panama and the Cayman Islands cut down the targeted Aedes aegypti mosquito population by over 90%, which was quite successful.

Researchers at the University of California who have pioneered a method that renders mosquito offspring unable to fly also adopted the approach. At Imperial College London, a team has also suppressed malaria in trials by modifying mosquitoes to only give birth to males, which do not bite and cannot transmit the disease.

According to an announcement made by Oxitec on January 19, latest tests in Piracicaba, Brazil last year cut the targeted mosquito population by 82% in a matter of months, and even led the city to expanding its project with Oxitec by allowing the company to build a new mosquito-producing factory in the region.

Piracicaba Mayor Gabriel Ferrato states, “Based on the results presented today, we decided to extend the project in CECAP/Eldorado district for another year and also signed a record of intent to expand the project to the central area of Piracicaba. This will bring to the city a new Oxitec factory to meet demand for years to come and help protect the public’s health with this clean and innovative technology.”

Photo Credit: Aquila @Flickr CC BY SA 2.0

Photo Credit: Aquila
@Flickr CC BY SA 2.0

Possible harm remains uncertain

However, people also bear concern towards the effect of GM mosquitoes, since introducing such a large amount of mosquitoes into the environment appears inadequate for human health. Some critics even believe that implementation of GM mosquitoes is happening too fast without enough understanding of the impact.

Dr. Luke Alphey, CSO of Oxitec, claims the company has been refining the techniques since 2009 and it offers a high degree of control. On its website, Oxitec says even if someone is bitten by a modified Aedes aegypti mosquito, no genetically modified DNA would enter the bloodstream since the risk of allergy or toxicity in such proteins is not found.

Trisha Kadakia, an obstetrics-gynecology resident, says in an article that this strategy is a valiant attempt to solve the problem at its root, but not without consequences. Kadakia writes, “We don’t have long-term data to provide answers on how it affects local ecosystems, food chains, public health, etc," and states the method may have a great impact on agriculture due to the possible development of resistance to the lethal gene or reaction to antibiotics.

Strategies taken worldwide

Countries struck by the Zika outbreak have been advising women to prevent pregnancy. The Brazilian government has also been frantically spraying affected regions, deploying more than 200,000 soldiers to assist in the fight.

Scientists in the US are working with authorities in Brazil to develop a vaccine that will cure and protect people against the virus. Health officials in Brazil say they expect to develop a vaccine for the Zika virus in about a year.

According to a recent announcement made by the Ministry of Health and Welfare in Taiwan, the research team formed to study epidemics will integrate short-term policies related to prevention methods and cures. A better warning system will also be built through promoting the study of vector mosquitoes and testing pesticides.

As for long-term plans, a corporate that targets mosquito-borne diseases may be established in Southern Taiwan on a national scale, hoping to lead further studies in the Asia Pacific region.

Edited by Olivia Yang

The News Lens
“Kill switch: breeding kamikaze mosquitoes" (CNN)
“Zika virus: Brazil hopes to develop vaccine in ‘one year'"( BBC)
“Fighting the Zika virus with mutant mosquitoes" (CNNMoney)
“UK company creates genetically-modified mosquitoes to help in fight against Zika" (News Australia)
“The potential solution to Zika is hidden in its name" (KevinMD)