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Mosquito-Borne Disease Prevention

Published on November 13, 2024

Mosquitoes are incredibly annoying pests, but preventing mosquito bites can protect you from a lot more than itching. In 2024, over 12 million cases of dengue have been reported in the Americas and the Caribbean, including local transmission in Florida, Texas, Hawaii, Arizona, and California [1]. Other outbreaks include highly deadly Eastern equine encephalitis, with 17 cases as of Nov. 5th in the US [2], West Nile with 1,195 cases [3], and Oropouche virus, which has seen outbreaks in South America and the Caribbean [4]. These diseases are often asymptomatic, but may also become neuroinvasive and cause significant long-term symptoms. 

Ongoing mosquito-borne illness outbreaks are a significant threat, but there are many steps we can take to reduce the risk of mosquito-borne illnesses:

Avoid Mosquito Bites:

  • Timing: Stay indoors when mosquitoes are most active, typically at dawn and after dusk.
  • Clothing: When outdoors, wear long sleeves, hoodies, sweatpants, socks, sneakers, and hats to cover as much skin as possible even in hot climates.
  • Repellents: Use insect repellent on clothing (preferred) or exposed skin, such as those containing DEET. Consider spraying clothes with permethrin in high risk conditions.　Please note that permethrin is toxic to people, cats, and aquatic life and may also cause allergic reactions in humans. Permethrin is a likely carcinogen. While it is very effective, its use should be targeted and carefully considered [5, 6]. 

Home and Environment:

  • Window screens: Ensure that window screens are intact and do not have holes to prevent mosquitoes from entering.
  • Water control: Eliminate standing water both indoors and outdoors where mosquitoes can lay eggs. 
  • Mosquito traps: Stand containers of water where mosquitoes may lay eggs, then discard this water, thereby interrupting the cycle at the larval stage. It is critical to discard these regularly; there are also chemical agents that can be added to interrupt development [7]. 

Public Spaces:

  • Stay informed: Stay informed about local mosquito activity, especially during heat waves.
  • Support local measures: Support local measures to manage mosquito populations and be aware of public parks or areas closed due to mosquito-borne disease risks.

Despite successful public health and government actions that have eliminated mosquitoes in various regions globally, mosquitos have recolonised most of their original habitats in the last several decades. Community-level action and individual actions are needed to both reduce populations and protect individuals from infection [8]. 

By following these guidelines, individuals and communities can significantly reduce the risk of mosquito-borne diseases.

H5N1 Update

There are important updates regarding the H5N1 avian flu outbreak in the US dairy industry since our last newsletter [9]. As of November 11th, the CDC reports that there have been 46 confirmed human cases of H5N1 in the US [10]. A serological study found 7% of infected herd farm workers had been infected (8 out of 115 workers tested) [11]. There are now almost 500 cattle herds confirmed infected in 15 states [12]. This indicates there are at least hundreds of farm workers who have been infected but have not been identified. The USDA also stated that the virus has been detected in a pig, which could be an isolated incident but experts warn that in conjunction with the seasonal flu, this could lead to a more dangerous hybrid virus that transmits from person to person [13, 14]. 

Canadian officials are also investigating what is assumed to be the first human case of H5N1 in a teenager in British Columbia [15].

Good News

Researchers in Switzerland and Germany are developing a new COVID-19 vaccine via “single-cycle infection SARS-CoV-2 viruses” (SCVs) that have been engineered to lack the essential Envelope gene [16]. While the SCVs are able to infect cells, producing an immune response, the infected cells do not produce more viable virus. This approach may be more suitable for immunocompromised individuals than live attenuated virus vaccines, which require one’s own immune system to clear the virus. Additionally, the researchers removed several genes in the SCVs that reduce immune cell activation, enabling their SCV vaccine to produce a stronger immune response. This study is particularly promising because the SCV vaccine was able to prevent airborne transmission in Syrian hamsters. Note: Necessary clinical trials for approval generally take 1.5 to 3 years if everything proceeds smoothly.

Who We Are

The WHN Science Content Team produces the WHN Newsletter and other science-based content. We are currently working on policy-relevant literature reviews and a panel on clean air advocacy. If you would like to join us, our Slack channel is #science-content-team, and if you’re not on Slack, you can email info@whn.global or fill out our interest form at https://whn.global/join-our-science-content-team/ . No formal science writing experience is necessary. 

Citations

  1. Centers for Disease Control and Prevention. (2024, November 7). Current dengue outbreak. CDC. https://www.cdc.gov/dengue/outbreaks/2024/index.html 
  2. Centers for Disease Control and Prevention. (2024, November 5). Current year data (2024) — Eastern equine encephalitis virus. CDC. https://www.cdc.gov/eastern-equine-encephalitis/data-maps/current-year-data.html 
  3. Centers for Disease Control and Prevention. (2024, November 5). Current year data (2024)  West Nile virus. CDC. https://www.cdc.gov/west-nile-virus/data-maps/current-year-data.html 
  4. Centers for Disease Control and Prevention. (2024, November 5). 2024 Oropouche outbreak. CDC. https://www.cdc.gov/oropouche/outbreaks/2024/index.html 
  5. Centers for Disease Control and Prevention. (2024, May 14). About permethrin-treated clothing and gear. CDC. https://www.cdc.gov/mosquitoes/prevention/about-permethrin-treated-clothing-and-gear.html 
  6. National Pesticide Information Center. (2009, July). Permethrin general fact sheet. NPIC. http://npic.orst.edu/factsheets/PermGen.html 
  7. US Environmental Protection Agency. (2024, June 3). Bti for mosquito control. EPA. https://www.epa.gov/mosquitocontrol/bti-mosquito-control 
  8. Dussfour, I. & Chaney, S. C. (2022). Mosquitopia: The place of pests in a healthy world, Chapter 14: Mosquito control. National Center for Biotechnology Information. https://www.ncbi.nlm.nih.gov/books/NBK585173/ 
  9. WHN Science Content Team. (2024, October 25). H5N1 update. WHN. https://whn.global/newsletter/h5n1-update/ 
  10. Centers for Disease Control and Prevention. (2024, November 8). H5 bird flu: Current situation. CDC. https://www.cdc.gov/bird-flu/situation-summary/index.html 
  11. Mellis, A. M., Coyle, J., Marshall, K. E., Frutos, A. M., Singleton, J., Drehoff, C., Merced-Morales, A., Pagano, H. P., Alade, R. O., White, E. B., Noble, E. K., Holiday, C., Liu, F., Jefferson, S., Li, Z.-N., Gross, F. L., Olsen, S. J., Dugan, V. G., Reed, C., … Levine, M. Z. (2024). Serologic Evidence of Recent Infection with Highly Pathogenic Avian Influenza A(H5) Virus Among Dairy Workers—Michigan and Colorado, June–August 2024. MMWR. Morbidity and Mortality Weekly Report, 73(44), 1004–1009. https://doi.org/10.15585/mmwr.mm7344a3
  12. Animal and Plant Health Inspection Service. (2024, November 8). HPAI confirmed cases in livestock. USDA. https://www.aphis.usda.gov/livestock-poultry-disease/avian/avian-influenza/hpai-detections/hpai-confirmed-cases-livestock 
  13. Lewis, T. (2024, October 31). Bird flu is one step closer to mixing with seasonal flu virus and becoming a pandemic. Scientific American. https://www.scientificamerican.com/article/h5n1-detected-in-pig-highlights-the-risk-of-bird-flu-mixing-with-seasonal/ 
  14. The Associated Press. (2024, October 30). Bird flu has been found in a pig for the first time in the U.S. NPR. https://www.npr.org/2024/10/30/nx-s1-5172615/bird-flu-pig-oregon-first-infection-h5n1 
  15. Kshatri, S. (2024, November 9). B.C. investigating 1st presumptive human avian flu case caught in Canada. CBC. https://www.cbc.ca/news/canada/british-columbia/first-presumptive-avian-flu-case-in-humans-1.7379630 
  16. Lett, M. J., Otte, F., Hauser, D., Schön, J., Kipfer, E. T., Hoffmann, D., Halwe, N. J., Breithaupt, A., Ulrich, L., Britzke, T., Kochmann, J., Corleis, B., Zhang, Y., Urda, L., Cmiljanovic, V., Lang, C., Beer, M., Mittelholzer, C., & Klimkait, T. (2024). High protection and transmission-blocking immunity elicited by single-cycle SARS-CoV-2 vaccine in hamsters. Npj Vaccines, 9(1), 206. https://doi.org/10.1038/s41541-024-00992-z