Zika Virus Not Here, But Mosquitoes Still A Public Health Threat

By: Alan Pollock

Topics: Health

Two species of mosquitoes present in the Americas are known to carry the Zika virus.  Neither the Aedes aegypti mosquito (pictured) nor the Aedes albopictus have been detected on Cape Cod.  JAMES GATHANY / CDC

With the Zika virus continuing to generate headlines – and threatening to derail the 2016 Summer Olympics in Rio – it's not hard to understand why local officials have had inquiries about the risk on Cape Cod.

Public health officials and entomologists say they have received calls from Cape Codders concerned about contracting the Zika virus from mosquitoes. While the two species of mosquitoes that carry Zika aren't present on Cape Cod, officials say there are plenty of other good reasons to keep biting bugs at bay.

Zika, best known for sometimes causing birth defects in babies born to infected mothers, is believed to be carried by just two species of mosquitoes present in the Americas, Aedes aegypti and Aedes albopictus. Neither has been detected yet in Barnstable County, according to Gabrielle Sakolsky, entomologist and assistant superintendent of the Cape Cod Mosquito Control Project. But the latter species, also known as the Asian tiger mosquito, has turned up in Bristol County.

“That population keeps popping up in New Bedford,” she said. Entomologists, working like detectives, traced the trapped tiger mosquitoes to a certain location where tires are stored outdoors. Those tires came to Massachusetts from New Jersey, which is within the natural range of that species.

“As long as those tires are holding some water, there may be mosquitoes developing in them,” Sakolsky said.

As it has since 1930, the Cape Cod Mosquito Control Project has been researching mosquitoes and performing the sometimes back-breaking work necessary to reduce their numbers here.

“We submit mosquitoes on a weekly basis throughout the summer” to laboratories that test for diseases like eastern equine encephalitis and West Nile virus, Sakolsky said. West Nile virus, first detected in the U.S. in 1999, can cause illness ranging from a mild fever to more serious disease like encephalitis or meningitis. Eastern equine encephalitis is very rare, but also very serious; it typically causes fever, a stiff neck, headache, and lack of energy. Swelling of the brain can cause patients to go into a coma, and about half of victims die from the disease. Most others are left permanently disabled.

“It's never good to be bitten by mosquitoes,” Sakolsky said.

The best way to prevent mosquito bites is to reduce their numbers, and that means eliminating the places where they breed.

“Go outside, walk around your yard and empty out any standing water in man-made containers,” she said. Mosquitoes don't fly far from home, so the mosquitoes on your property might very well have hatched there. Look for things like flowerpots, overturned trash can lids, and particularly “the tarp on the boat,” Sakolsky said.

It's wise to limit outdoor activity when mosquito feeding is at its peak, typically around dawn and dusk. Wearing long-sleeved clothing can help, and it also makes sense to keep window screens in good repair. When it comes to bug spray, it pays to read the fine print, she added.

“Check the label of the repellent you're going to use,” Sakolsky said. The product should have an EPA registration number that shows that the product was tested both for its effectiveness and for safety for use on skin. Choices range from the synthetic compound known as DEET to plant-based alternatives like oil of lemon eucalyptus. Beware other so-called “natural” repellents that haven't been tested for safety or effectiveness. “I see a lot of those products out there,” Sakolsky said.

At least locally, when it comes to Zika, fear outweighs the actual risk. Naturally, Cape Codders can still contract the virus by traveling to tropical areas where it is prevalent or potentially by having unprotected sex with an infected person – though this possibility is still being researched. But when it comes to contracting the disease from a Cape Cod mosquito, that doesn't appear likely.

“I completely understand why people are calling,” she said. Often those who call are parents-to-be or grandparents-to-be who are worried about the virus. “They'll be spending time on the Cape and I think they want to alleviate their anxiety,” she said.