Good mozzie, bad mozzie

Malaysia is basing its faith in Wolbachia, but we advise a mutation warning

MOSQUITOES are deadly. According to an article in the Scientific American on June 1, 2015, Aedes aegypti — the mosquito that spreads yellow fever, dengue, Zika and Chikungunya — killed more American troops than enemy fire in the Spanish-American War in 1898. In Malaysia, too, they are biting above their weight. Up to Feb 23, they have claimed 40 lives, double the number for the same period last year. No wonder the Institute for Medical Research (IMR) is following in the footsteps of Australia by getting good mozzies (as mosquitoes are called Down Under) to fight bad mozzies. This is how it works: Aedes aegypti mosquitoes infected with a bacterium called Wolbachia are released into the wild to immunise mosquitoes. IMR has been doing this since March 28, 2017, and has released three million Wolbachia-infected mosquitoes in seven dengue hotspots. IMR claims an 80 per cent success rate.

While it may be too early to preen oneself, IMR’s elation is understandable. This is a groundbreaking effort as it was in Australia. Plus, Malaysia has tried other ways to fight the menace and failed. Innocuous mosquito nets, toxic sprays and deadly DDT (dichlorodiphenyltrichloroethane) have all misfired. The last was banned as a pesticide worldwide under the Stockholm Convention in 2001 after it was found to pose great danger to wildlife and the environment. Wouldn’t the Wolbachia-infected mosquito pose a similar threat? IMR thinks not, but Universiti Kebangsaan Malaysia’s parasitology and entomology expert Associate Professor Dr Hidayathulfathi Othman raises interesting questions. The number to be released must be a minimum of 20,000 to 50,000 in one go because between 20 per cent and 30 per cent of the mosquito population must be infected to push dengue rates down. The strains, too, must be the right one as some just do not work at temperatures between 26 °C and 37 °C. Also, what works for Aussie mozzies may not work for Malaysian mosquitoes.

There may be other dangers which we may not know. Life forms develop resistance, and this may happen in this experiment. If this fear turns out to be true, then we will be faced with mosquitoes that develop sterner stuff than they are naturally endowed with. We have seen this happen with DDT. IMR and Hidayathulfathi both say infecting Aedes aegypti with Wolbachia isn’t the same as genetically modifying the mosquitoes. But we have a different take. Infecting the mosquitoes with Wolbachia where there is none may not be on all fours with genetic engineering, but it is close. Mutation cannot be ruled out. Twenty years — that is the number of years in total researchers have spent on this Wolbachia project — is too short a time to know about mutation for certain. Just because we haven’t seen it happen, doesn’t mean it wouldn’t occur. DDT took a lot longer before disaster hit home.

Consider this. As the experts acknowledge, Aedes aegypti does not come endowed with Wolbachia bacterium. The scientists inject it into the mosquito’s eggs in the lab. Isn’t this tinkering? Are we not playing God? This is one hubristic step we are duty-bound to caution against.

While it may be too early to preen oneself, IMR’s elation is understandable.