Sterilizing mosquitoes may be the answer to curb Zika, Dengue, Chikungunya, WHO reports

By Angela Betsaida B. Laguipo, BSNNov 18 2019

A new technique that sterilizes male mosquito through radiation shows promise in fighting mosquito-borne illnesses, including Zika, dengue and chikungunya. Soon, health experts plan to test the technique as part of global health efforts to control these diseases.

Dubbed as the Sterile Insect Technique (SIT), the innovative technology has bee developed decades ago to target crop-eating insects in the United States. Now, UN researchers have studied the technique over the past ten years to adapt it to mosquitoes.

Working with the World Health Organization (WHO) tropical diseases program, the UN’s special programme for Research and Training in Tropical Diseases (TDR) plans to develop a pilot program for countries that are interested in utilizing SIT on mosquitoes to test its effect on disease transmission.

Image Credit: WHO

They have now drawn up guidelines for countries who are interested to tackle disease outbreaks caused by mosquitoes, including the aedes aegypti species that cause potentially-fatal illnesses such as dengue fever, and other mosquito-borne diseases, including chikungunya and Zika virus disease.

Controlling mosquito populations is the only measure used today to reduce the risk of vector-borne diseases. At the moment, many countries with many cases of these mosquito-borne illnesses rely on insecticides to control the spread and proliferation of mosquito populations.

However, with the use of insecticides for a long time, some species of these mosquitoes have already developed resistance. Further, insecticides have residual effects on the environment. Health experts urge for the development of alternative methods, which are safer and more effective.

SIT involves rearing large numbers of sterilized male mosquitoes in facilities and laboratories and releasing them to mate with females. These male mosquitoes can’t reproduce; hence, the mosquito population will decrease over time.

The scientists will also evaluate the entomological efficacy to provide guidelines and to design a program that will implement the method throughout many countries. The program will take about four years before it is known whether pilot tests are successful in reducing disease transmission.

“Evidence of the efficacy of the SIT in reducing disease transmission will help inform larger-scale deployment of the technology,” the researchers said.

Health effects of mosquito illnesses

The diseases spread through the Aedes aegypti species of mosquitoes can take a toll on many lives. For instance, dengue fever, when it’s left untreated, can lead to a potentially fatal complication called dengue hemorrhagic fever. This complication causes many deaths linked to dengue fever due to the risk of bleeding.

Many countries, particularly in warm and tropical areas, are at a higher risk of dengue fever.

“Half the world’s population is now at risk of dengue. And despite our best efforts, current efforts to control it are falling short. We desperately need new approaches, and this initiative is both promising and exciting,” said Dr Soumya Swaminathan, WHO Chief Scientist.

The incidence of dengue has dramatically increased because of transport and travel, unregulated urbanization, insufficient sustainable vector control tools, and environmental changes. Many countries have reported dengue outbreaks, including the Philippines, Brazil, and Bangladesh, among others.

The disease has caused 3.34 million cases in 2016 alone, with a total of 128 countries at risk. Moreover, Zika virus has caused an estimated 1.5 million cases between 2015 and 2016, while chikungunya has caused 1.2 million cases in 2015.

Sterile Insect Technique in depth

The Sterile Insect Technique (SIT) is an environmentally-friendly pest management method first used by the United States Department of Agriculture. Successfully used for about 60 years, it has targeted insect pests that attack crops and livestock, including the New World screwworm fly, Mediterranean fruit fly, and the Tsetse flies.

In this method, male insects are sterilized and released in a target area. When these sterile males mate with females, they are no offspring. When this cycle goes on, it can markedly reduce the target wild insect population over time.

Male mosquitoes will be used since they don’t bite and can’t pose a risk of disease transmission. The scientists will release the male mosquitoes through a drone release system.