Zika and Mosquitoes: How to Protect Yourself

For many parts of the United States, springtime means the start of mosquito season. Depending on the species and local weather, hibernating insects wake when it warms up or hardy eggs start to hatch. Rising temperatures also mean rising fears of mosquito-borne diseases in this country — West Nile virus, dengue fever, and the latest threat, Zika virus.

Often, Zika infection has no symptoms. If there are any, symptoms are mild, such as fever, joint pain, and rash, and last a few days to a week. In some people, it might cause a nerve disorder called Guillain Barre syndrome that causes muscle weakness, sometimes permanently. But one of the most worrying effects is that catching Zika in pregnancy seems to be linked to a serious birth defect called microcephaly. Seen by the thousands in Brazil, these babies are born with heads that are smaller than normal and often grow up with a range of developmental disabilities. We don’t have the full picture yet, but researchers think that about 1 percent of pregnant women infected with Zika will have disabled babies.

Because of this, the Centers for Disease Control and Prevention (CDC) recommends that pregnant women avoid travel to areas with Zika, which now include three US territories (Puerto Rico, American Samoa, and the US Virgin Islands), and more than 35 other countries and territories in the Americas, Oceania (Pacific Islands), and Africa. Especially if you’re pregnant, you’ll want to check the CDC website and talk to your doctor before and after you go abroad in the near future.

What if you’re staying at home or travelling within the US this spring or summer? So far, no locally acquired cases have been reported in the continental United States (all cases have been brought here by recently returned travelers). There have been a few cases of people passing on the virus to others through sex, so recent travelers and their partners may need to be extra careful — the CDC is even advising people who have had Zika infections to wait a few months before trying to have children.

But as it warms up, it’s possible that Zika could become a wider concern in the States this summer.

A recent study published in PLOS Currents: Outbreaks identifies American cities that have Aedes aegypti mosquitoes (the primary carrier of Zika) in the summer. The cities with higher levels are mainly in the South and Northeast and include Miami, Orlando, New Orleans (high levels) and Houston, New York, and Atlanta (moderate levels). Some of these places also see a lot of travel to and from Zika-affected countries. That combination could mean Zika becomes one more mosquito-borne disease to worry about at home. In Florida, the governor has already declared a state of emergency in four counties to combat the Zika threat.

Image: AJ Monaghan et. al. PLOS Currents: Outbreaks. 16 March 2016.

So how do you protect yourself? Your best bet is to avoid getting bitten this mosquito season, if only to avoid those nasty bites. Here are some tips from experts.

1. Stay indoors during peak hours. Limit outdoor activities during dawn and dusk, when mosquitoes are most active — although some species, including A. aegypti, tend to bite in the daytime, too. Shut windows and doors, or at least make sure they’re covered with mesh screens free of rips or tears where mosquitoes can wriggle through. Turn on the AC. “You want to try do everything you can to keep the mosquitoes out,” says William Schaffner, a professor of preventive medicine at Vanderbilt University Medical Center. That holds especially true for A. aegypti. “This is a rascal that likes getting into your house” — where it proceeds to lie in wait throughout the day, Schaffner says.

2. Dress long, loose, and light. If you do venture outdoors, wear loose-fitting long sleeves and pants to expose as little of your flesh as possible to hungry mosquitoes. Since they tend to gravitate to darker blues, reds, and purples, opt for lighter hues.

3. Spray on the repellent. Most mosquito repellents have a chemical called DEET, which is very effective against mosquitoes and other bugs. Despite some fears, DEET is considered safe even for pregnant women and children. Just use a little care.

• Choose a product with 10 to 30 percent DEET; according to the CDC, concentrations over 50 percent don’t add extra protection and can be toxic.
• Use only as directed. Spray in an open area, and away from the mouth. DEET is toxic when swallowed.
• According to the CDC, don’t use it on babies under two months old.
• Don’t apply it to kids’ hands in case they put them in their mouth or touch their eyes.
• Reapply every 3 to 4 hours if you’re sweating or swimming (check the directions). It’s best to use separate sunscreens and repellents to avoid applying too much DEET.

According to the CDC, certain natural repellents like oil of lemon or eucalyptus can offer protection too, but they may not be as effective. You can also treat clothing and netting with a long-lasting permethrin spray. (Do not apply permethrin directly to the skin.)

4. Drain or cover standing water. Since mosquitoes need standing water to breed, eliminating standing water can vastly reduce their numbers. Schaffner suggests “what we used to call in Boy Scout camp, ‘policing the area.’ In other words, make a survey of the surroundings in your own home.” As a general rule, dump or clean out anything that could hold water for more than 10 days, which is how long most mosquitoes take to hatch and mature.

Keep your eyes peeled for these common breeding sites:

• Pets’ water bowls: Wash and change Fido’s water bowl daily. Mosquitoes often lay eggs along the edges, Wesson says.
• Garden items. That includes décor, like birdbaths and fountains. Make sure tarps and covers are drawn taut so water doesn’t collect in folds and depressions.
• Plants. Water plants and grass carefully to avoid puddles. Dump out the drainage that collect excess water from potted plants.
• Rain barrels. Cover rainwater collection barrels with mesh comparable to window screening, fine enough to prevent eggs from slipping through.
• Gutters. Peek at your gutter periodically, or ask your building manager to do so, if you live in an apartment. Realign with the downspout, if necessary. “Sometimes they get beaten about…so they don’t drain completely,” Schaffner explains. Repair any sagging, and clear leaf debris, which can also cause water to pool.
• Spouts. Cover downspouts that drain water from gutters with mesh to prevent mosquitoes from entering. Many downspouts are made from corrugated metal, whose dips and valleys can also collect water, says Dan Schamberger, mosquito program manager at the Maryland Department of Health and Mental Hygiene. “It’s nice, dark, and moist and boom, you got all kinds of mosquitoes.”
• Swimming pools. Although typically not a huge danger, they can make for ideal breeding sites if left untreated and stagnant.
• Toys. Clear the backyard of kids’ toys, which can also cup water.
• Trash. Cover trash cans to prevent them from filling with water. Notify your city’s sanitation or public health department if you spot a lot strewn with tires or other junk. (Most major cities have a 311 phone line you can call for service requests.)

5. Or, try larvicide. If you have problem areas of water around your house, you can treat them with larvicides approved by the U.S. Environmental Protection Agency (EPA). These chemicals kill immature mosquitoes (larva). They often come in pellet, granular, tablet, or briquette form. Most won’t harm humans, pets, or even other insects, though the EPA has banned one called temephos.

6. Dim the lights. Mosquitoes, like many insects, find bright light irresistible. Dim or turn them off completely. Robert Yanity, a spokesperson for the South Carolina Department of Health and Environmental Control, suggests bulbs that give off yellow light. Avoid black light, though, which attracts some mosquito species, Wesson says. (Bug zappers use this fact to attract them.)

7. Flip on the fan. Schamberger suggests setting up an electric fan on your porch or deck. Not only are mosquitoes too weak to fly against the draft, it might also help dissipate the carbon dioxide from our breath that attracts them.

8. Shower often. Some studies show that mosquitoes are drawn to human sweat and body odor. Besides cooling you off, a quick shower might make you less attractive to the bugs.

9. Camp smart. “Do the research before you go,” Yanity says. Know whether to expect lots of mosquitoes at your destination. Whenever practical, cover up with long pants, socks, long-sleeved shirts, and scarves. On uncovered areas of skin, use plenty of repellent, and make sure your tent has mesh screens with no rips or tears. Hang up an insecticide-treated mosquito net (available at most outdoor supply stores) over outdoor sleeping areas. If you’re outside at night, stick close to a campfire — smoke can help keep mosquitoes at bay.

10. Know what to avoid. Lots of products claim to protect against mosquitoes – including “some that people wishfully hope will work, as well as others where there’s really no data to suggest that they work,” says Daniel Kass, deputy commissioner at the New York City Department of Mental Hygiene. Some are just dangerous. Kass suggests avoiding these:

• Foggers. Spraying chemicals that kill adult mosquitoes might not be effective — or safe, for that matter, Kass says.
• Coils. Burning mosquito coils produces smoke meant to repel bugs, although research on exposure to this smoke has raised health concerns. Some are illegally imported and contain toxic pesticides.
• Citronella candles. They might smell better than DEET but don’t offer much more protection than other candles.

Mosquitoes are responsible for more human deaths worldwide than any other animal on the planet, and despite our best efforts, they’re tough to outwit. Most likely, you’ll still get a few bites this summer, but don’t panic — the odds of catching Zika are low in this country. If you ever suspect you might have symptoms of Zika or a similar illness, contact your doctor for advice.

Editor: Deepi Brar

Melissa Pandika is a freelance writer in Oakland, California.

Selected references

• Centers for Disease Control and Prevention. Zika Virus. CDC website. [Link]
• Cauchemez S, Besnard M, Bompard P, et al. Association between Zika virus and microcephaly in French Polynesia, 2013–15: a retrospective study. Lancet. 2016.
• Frequently Asked Questions. American Mosquito Control Association. 2014. [Link]
• Monaghan, AJ, et al. On the Seasonal Occurrence and Abundance of the Zika Virus Vector Mosquito Aedes Aegypti in the Contiguous United States. PLOS Currents: Outbreaks. 16 March 2016. [Link]
• Mosquito Prevention. Dallas County Health and Human Services. 15 March 2016. [Link]
• Nasci, RS, et al. Protection Against Mosquitoes, Ticks and other Arthropods. CDC Health Information for International Travel 2016 (Yellow Book). [Link]

MELISSA PANDIKA
Rally Health