CEO Prof. CHAN responds to new prevention technologies for Chikungunya Fever

Recently, the importation of chikungunya fever into Hong Kong has raised concerns, with suggestions to explore new prevention and control technologies, including the commonly referred “using mosquitoes to combat mosquitoes” approach. In response to media inquiries, Prof. CHAN Ying-yang, Emily, CEO of GX Foundation, presented several important viewpoints. She stated:

1. The so-called “using mosquitoes to combat mosquitoes” actually refers to releasing large numbers of Wolbachia-infected Aedes albopictus (hereafter referred to as Aedes mosquitoes) into the environment. These mosquitoes and their offspring have a lower probability of transmitting viruses, but they do not possess the ability to “combat” other mosquitoes. Therefore, the term “using mosquitoes to combat mosquitoes” is inaccurate.
   
   
2. The fundamental theory behind the Wolbachia method involves artificially breeding Aedes mosquitoes in laboratories and infecting them with Wolbachia bacteria, thereby reducing their ability to transmit chikungunya or dengue fever viruses. Under certain conditions (see Appendix 1), this may also cause the offspring of these artificially bred and infected mosquitoes to lose their ability to transmit these viruses. However, it is important to note that there is no scientific evidence confirming whether offspring produced from mating between Hong Kong’s native Aedes mosquitoes and artificially bred, Wolbachia-infected Aedes mosquitoes will completely lose their viral transmission capability.
   
   
3. This biological method is not new. Its implementation in a few countries has yielded insignificant results, and based on global practical experience, several key issues require attention.
   
   
4. First is the issue of cost and resources. Some countries have indicated that this method may require millions of dollars in basic expenses, alongside coordination with mosquito eradication measures. The simultaneous use of chemical insecticides will inevitably affect and kill the artificially bred Wolbachia-infected mosquitoes.
   
   
5. Second is ecological impact assessment. Considerations must include the suitability of the scale and location of implementation, including the role of natural predators and wild mosquitoes. Additionally, while the release of large numbers of Wolbachia-infected mosquitoes does not transmit chikungunya or dengue fever viruses, they still bite humans, causing discomfort and unnecessary panic among residents. Lastly, precaution against unknown factors, such as potential impacts on local ecosystems, is essential.
   
   
6. In terms of timeliness, the effects of releasing Wolbachia-infected Aedes mosquitoes are not immediate. It requires a period of mosquito mating and reproduction cycles before results become apparent. Authorities must also continuously monitor viral mutations and changes in mosquito adaptability.
   
   
7. In Singapore, where dengue fever is endemic, the government once released Wolbachia-infected mosquitoes in a community, successfully reducing dengue cases initially. However, after sustained releases, dengue cases surged in 2024, reaching 1.36 times the number recorded in 2023.
   
   
8. Furthermore, other scientific studies indicate that Wolbachia-infected mosquitoes can reduce dengue incidence by 38%, but only reduce chikungunya incidence by 10%. Therefore, governments must conduct thorough scientific evidence-based research.
   
   
9. To effectively prevent and control Aedes-borne diseases such as chikungunya and dengue fever, comprehensive mosquito prevention and eradication efforts are essential. After two years of field research and preparation, GX Foundation has launched large-scale mosquito control programmes in multiple countries since 2024, based on the principle that “no mosquitoes mean no mosquito-borne diseases”, including dengue and chikungunya. GX Foundation focuses on physical means, installing over 18,000 mosquito lamps across six countries threatened by dengue and malaria, supplemented by mosquito nets, rapid test kits, sticky fly traps, and public health education, achieving significant results. Initial successes in Timor-Leste (Southeast Asia) were published in the UK’s authoritative medical journal The Lancet in March this year and endorsed by Timor-Leste’s national leaders and WHO representatives. Similar projects launched last year in Honduras (Central America) also yielded remarkable results. Other countries include Laos, Cambodia, Vanuatu, and Djibouti. Mosquito lamps and nets have no side effects or long-term consequences, are low-cost, and have received support from national health ministries and partners.
   
   
10. Mosquitoes are the most lethal pests to humans. Since 2000, mosquito-borne diseases have caused an average of 2 million deaths annually worldwide. These diseases are a major challenge in global public health, but their complexity demands diverse control methods. Hong Kong society must deepen its understanding of theory and practice. I hope all sectors will pay close attention and fully cooperate with the government’s mosquito control measures.