By Lok R. Pokhrel, assistant professor of environmental health in the Department of Epidemiology and Biostatistics
In just three weeks this summer, hurricanes claimed the lives of more than 150 people in Texas, Florida and Puerto Rico and caused hundreds of billions of dollars in damage. Around the same time, monsoon flooding in Nepal, India and Bangladesh claimed more than 1,200 lives and affected millions more. Now, public health officials fear new health disasters in these areas.
Torrential rains and flooding turned cities into microbe-infested swamplands. Water from flooded landfills, chemical sites and sewage found their way into these areas. Residents risk exposure to toxins in standing water, which can lead to short- and long-term illnesses.
As significant as these risks are, there is yet another problem lurking in the water: mosquitoes.
Mosquito populations increase after flooding, when standing water serves as a breeding ground for many species. The public must understand, then, why mosquitoes are so dangerous and know how to minimize their risk of exposure to mosquito-borne diseases.
Mosquitoes kill more humans worldwide than any other animal, causing about one million deaths per year. Zika, primarily carried by the Aedes species of mosquito, has garnered much attention in recent years. More than 5,300 cases were reported in the United States as of September 2017, with more than 37,000 in U.S. territories, according to the Centers for Disease Control and Prevention.
Notably, Texas and Florida are among the top four states where Zika cases were reported before the hurricanes. This is likely due to their warm climates and the number of international travelers they host. That makes it especially important for officials there to reduce the risk of people contracting the disease.
It’s not an easy task. Currently, no vaccine or drug prevents or treats Zika. Mosquito nets aren’t much help: The Aedes often bites during the day, when people are outdoors, as opposed to the nighttime when people are more likely to stay in one place. And, in general, conventional pesticides that control mosquitos are quickly becoming obsolete as the insects develop resistance to them.
At the College of Public Health, we are exploring how nanotechnology can help control mosquito populations. Nano-sized particles—up to 10 times smaller than a micrometer and nearly imperceptible even with powerful electron microscopes—can penetrate a mosquito’s cell, while larger molecules typically find it harder to enter a cell and bioaccumulate.
This means we potentially can develop new, more effective pesticides. Since the nanoparticles are so small, a nanoparticle-driven pesticide would work in lower doses than current, high-volume pesticides. This would reduce their costs and have less of an impact on other life forms.
Thanks to preliminary findings, we have applied for a two-year grant from the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health. Right now, we know these particles can penetrate the cells, but we don’t know exactly how. If funded, our hope is that we can apply this new knowledge to controlling other species of mosquitoes, including Anopheles and Culex.
Understanding this further can lead to developing practical products that can keep people safe from diseases.
How to minimize mosquito exposure and potential health risk in flood and mosquito-prone areas:
- ‘Tip and toss’ objects that may hold standing water, such as old tires, cans, buckets, vases, etc.
- Cover standing water with soil if possible.
- Use EPA-approved mosquito repellents.
- Wear long sleeve clothing or clothing treated with permethrin.
- Mosquito-proof your home by screening your porch, doors and windows.
- Avoid travel to areas with high Zika infections.
- Avoid becoming pregnant if you or your partner is infected with Zika