Late in 2019, Singapore’s National Environmental Agency opened a new facility with the aim of squashing dengue. This new facility is actually generating and intends to release around 5 million Wolbachia mosquitos per week once at full capacity.
But first, what is the Wolbachia mosquito?
Source: World Mosquito Program
Wolbachia is a natural bacterium present in up to 60% of insect species, including some mosquitos. The World Mosquito Program’s research has shown that when Wolbachia is artificially introduced into the Aedes aegypti mosquito – the primary species responsible for transmitting human viruses such as Zika, dengue, chikungunya, and yellow fever – Wolbachia can help to reduce the transmission of these viruses to people. They are now breeding Wolbachia-carrying mosquitos in partnership with countries to be released in areas affected by mosquito-borne diseases. So far, the evidence shows that dengue incidence is significantly lower in treated communities. Additionally, the Wolbachia strategy can be seen as a comparable approach to gene-editing mosquitoes, that after a few of their short generations go by, they are no longer able to reproduce and die out.
Circling back, Singapore is implementing this technique because of a surge of dengue cases last year, a surge that is projected to worsen due to higher than average temperatures; the continued climate change trend is likely to exacerbate the dengue situation in Singapore. Consequently, they are placing emphasis on breeding lab-created Wolbachia-infected male Aedes aegypti mosquitoes with females, so that the eggs will not hatch. Male Wolbachia-infected mosquitoes also do not bite. Wolbachia can be seen as a way to enhance, not replace, existing vector control strategies.
Are these strategies safe?
Three independent risk assessments have been conducted on the Wolbachia method. The results concluded that there is negligible risk associated with the release of Wolbachia-carrying mosquitoes and that contact with the Wolbachia bacterium does not affect people, animals, and the environment. The World Mosquito Program has received regulatory approval from relevant government bodies in all the countries where they are releasing Wolbachia-carrying mosquitoes and do so with the consent and permission of the communities.
What about malaria?
Though the effects of Wolbachia are not as extensive as in Aedes aegypti, a few studies in Anopheles did show that the presence of the bacteria negatively correlates with the plasmodium parasite; however the Wolbachia bacteria is not, at this time, vertically transmitted. Even though the focus of the Wolbachia methods is to attack dengue, the technology and overall ramifications also have important implications for the malaria community.