Hurricane Matthew’s Potential Impact on the Spread of Zika

In the wake of Hurricane Matthew, there have been concerns regarding how the storm might affect the spread of vector-borne diseases including Zika. Although local transmission of Zika virus has only been confirmed in Florida, coastal areas up through the Carolinas could experience increased human exposure to mosquitoes as they recover from Hurricane Matthew.

An article published by Adrienne Lafrance in The Atlantic looked at this topic. Lafrance cites research conducted at Tulane University that examined the incidence of West Nile disease in areas affected by Hurricane Katrina in 2005. Researchers found that the number of people with neurologic disease associated with West Nile Virus had increased sharply in the three weeks following Hurricane Katrina.

What does Hurricane Matthew have to do with Zika?

West Nile Virus, just like Zika Virus, is spread by mosquitoes, and a hurricane can have interesting effects on both human and mosquito activity. Specifically, hurricanes can create four main conditions that might lead to a more favorable environment for breeding, which can contribute to increased exposure to mosquitoes and also the spread of Zika.

Increased mosquito activity and exposure are caused by:

• Standing Water: As Hurricane Matthew skirted the southeastern coast of the U.S. nearly two weeks ago, it dumped over 15 inches of rain in some areas which led to flooding. Storm surge from Matthew reached nearly 10 feet in some areas, leading to coastal flooding. These two types of flooding, from rain and storm surge, mean that when the waters recede, there will likely be many residual reservoirs of water that can become effective mosquito breeding grounds. Because mosquitoes do not travel far from their breeding grounds, the closer you or your home is to residual areas of standing water, the more susceptible you may be to mosquito bites.
• Power Outages: More than two million people from Florida to North Carolina lost power as a result of Hurricane Matthew, which means no air conditioning. This forces people outdoors, or to open their doors and windows to keep cool, allowing mosquitoes into their homes.
• Infrastructure Damage: Even minor damage to doors, window screens, or the infrastructure of a building can allow mosquitoes to easily get inside homes.
• Recovery Efforts: Cleanup and recovery efforts require many residents to spend more time outdoors, making them more susceptible to mosquito bites and, in turn, to possible Zika exposure.

Although the increase in West Nile observed after Hurricane Katrina could be linked to other variables besides those listed above, it is important to take heed and keep a watchful eye on Zika’s potential to spread in the aftermath of Hurricane Matthew. Even though local transmission of Zika virus has only been confirmed in the Sunshine State, those in coastal areas from Florida to the Carolinas should be vigilant about protecting themselves from mosquito bites and minimize exposure as much as possible during recovery efforts.

Author: Sid Baccam, Computational Epidemiologist, IEM