Summer of the Mosquito: Part 2
A female Culex Pipiens, the main vector for West Nile Virus, taking a bloodmeal from a unsuspecting host.
I remember the first West Nile outbreak in the United States, in 1999. I lived in the New York area at the time and the first thing I remember was people being terrified by the mysterious bird die-offs. Following the identification of West Nile Virus in humans, the fear that a potentially fatal illness may be lurking in the ever too prevalent mosquito population scared people to the point that they were afraid to go outside. This first year resulted in 62 positive human cases, including 7 fatalities (all of these cases were in New York).
Much has changed since 1999. Since 1999 there have been over 30,000 reported cases of West Nile reported in 48 States, causing cities, states, and counties to successfully implement programs to monitor and control mosquito populations. Also, bird populations have developed immunity to the virus and there are no longer birds dying off from West Nile. Despite the prevalence of West Nile, the general public has begun to relaxing its fear of the outdoors and mosquitoes.
Unfortunately, this summer a West Nile outbreak has developed in Texas, relighting Americans fear of the disease. According to the Center for Disease Control(CDC) as of September 4, there have been 1,993 confirmed cases of West Nile Virus in the United States, 45% of these cases have been reported by Texas. People have once again started to wonder if it’s safe to go outside.
Though fall is just around the corner here in the Northeast, mosquito “season” is far from over, especially in the south. I have put together a brief list of advice for reducing your risk from being bitten by mosquitoes and potentially acquiring West Nile based on my experience doing mosquito and other vector-borne disease research and prevention.
1. Personal Protection
Species of the genus Culex (the genus of mosquitoes responsible for human cases of West Nile Virus) prefer to feed at dusk, night, and dawn. By wearing long sleeves and pants you can try to protect yourself from skeeters without the use of repellants (though I do recommend usage of repellants because I have been bit through clothing on numerous occasions).
The use of repellant has been deemed safe and effective by the CDC, which recommends the use of “conventional repellants” like DEET and Picardin and “biopesticide repellants” like Oil of Lemon Eucalyptus, PMD and IR3535 as active ingredients in repellants.
2. Source Reduction
Source reduction is an important and ecological approach to reducing mosquito populations. Removing standing water and open containers from your property eliminates potential breeding grounds for Culex mosquitoes (and also for container-breeding mosquitoes like the invasive Tiger Mosquito Aedes Albopictus). Standing water like inflatable pools and birdbaths should be checked regularly because there is no such thing as a tadpole in a birdbath. As we used to say “Check it or Chuck it”.
3. Attempt to Mosquito Proof Your Home
During the summer heat, open windows are an efficient way to cool down your house. Not all species of mosquitoes come indoors, but to protect yourself from those who do its important to maintain your window screens and seal all possible entry points.
I have always found the epidemiology and ecology relating to vector borne diseases like West Nile Virus fascinating. There are so many factors (e.g. temperature and rainfall) that can lead to an outbreak or change in disease distribution. As the climate (theoretically) continues to warm surveillance and control of mosquitoes will become more and more important. Hopefully my prevention advice will help you take some control over your risks factors for West Nile.
Note: Despite the current outbreak the chances of acquiring West Nile Virus and getting sick are still very low. Chances of getting ill are higher for those older than 50 years and the immune compromised. Also, not everyone infected with West Nile will develop symptoms. According to the CDC only 1 in 5 infected experience symptoms; and of those infected less then 1% develop severe neurological symptoms.
Culex via Shutterstock