Weaponized Mosquitoes Are Being Deployed to Reduce Vector-Borne Diseases

The World Mosquito Program (WMP), a not-for-profit group involving companies working with Monash University, in Melbourne, Australia, is using mosquitoes to prevent mosquito-borne diseases such as Dengue, Zika, Chikungunya and Yellow Fever. Its reach is 14 countries today located in its own native Australia, Asia, Oceania, and Central and South America. It has been using mosquitoes for disease prevention since 2011.

The science behind its disease prevention program revolves around Wolbachia, an intracellular bacteria found in insects, other arthropods, arachnids (spiders and mites), and crustaceans.

Wolbachia is present in between 50 and 65% of all insect species. It provides its insect hosts with an important benefit, blocking other pathogens from infecting them including all the ones mentioned above. Wolbachia-infected mosquitoes, therefore, when released into the wild to mate with native Aedes aegypti mosquitoes help reduce the spread of vector-borne diseases. Although Aedes aegypti mosquitoes originated in Africa, today they can be found across the world.

When a mosquito hosting Wolbachia bites a human is there any danger to the latter? The WMP states the bacteria “poses negligible risk to humans and the environment.” It poses no danger to other animals as well. That’s why the WMP has received regulatory approval from the governments of countries where it is breeding and releasing Wolbachia mosquitoes in areas where vector-borne diseases are prevalent.

This method of vector-borne disease control is cost-effective and self-sustaining. It is cheaper and less harmful to ecosystems than trying to eradicate disease-spreading mosquitoes using insecticides. It is far less expensive than programs involving the breeding and release of genetically modified sterile male mosquitoes.

The diseases Wolbachia mosquito release programs are targeting have wreaked havoc on human populations.

• Dengue fever infects 390 million annually in Southeast Asia, the Western Pacific, the Americas, and Africa. Its occurrence is on the increase with the World Health Organization (WHO) recording a ten-fold rise in cases from 500,000 in 2000 to 5.2 million in 2019. An average of 20,000 die from it every year. In 2017, it killed more than 40,000.
• Zika is known to have caused microcephaly in infants born of mothers bitten by Aedes mosquitoes carrying the virus. The first known cases of human infections in Africa date to the 1950s. It subsequently spread around the world with known cases in 89 countries. There have been few reported deaths from Zika.
• Chikungunya is caused by the CHIKV virus and was first identified in Tanzania in 1952. It has spread to 110 countries through Aedes mosquitoes since then. Although the debilitating symptoms of Chikungunya can last a long time, the disease is rarely fatal.
• Yellow Fever poses a high-impact, high-disease threat to human populations. Spread by Aedes and Haemagogus mosquitoes as well as ticks infected with arbovirus, the disease is endemic in 34 African countries, and 13 in Central and South America. A single-dose vaccine to prevent it has been developed and is widely available. It provides lifetime immunity. For those who have been infected and experience the severest symptoms, the death rate is 47%.

The WMP release program was recently highlighted in Brazil. A technical worker for the Oswaldo Cruz Foundation, Waldeir Barbosa da Silva, described what’s involved. da Silva has been releasing between 150,000 and 200,000 Wolbachia mosquitoes in Niterói, in Southeast Brazil almost daily. The program for rearing Wolbachia-hosting mosquitoes has even involved schools where students observe the eggs and larvae of the insects nurturing them until the adults emerge from the pupae state. The program is called Wolbito, the name given to the Wolbachia mosquitoes. In Brazil, Wolbito is in high demand in five cities. Plans to build a mosquito factory this year are underway.

Is Wolbachia a panacea for mosquito-borne diseases? No. You’ll notice malaria is not in the mix. But along with the other techniques mentioned in this posting to control the spread of vector-borne diseases, it is a highly desirable program and doesn’t involve chemical sprays that have deleterious effects on other wildlife and humans.