Zika virus update for travelers

The Pan American Health Organization currently reports that 40 countries and territories in the Americas have confirmed local mosquito-borne transmission of the Zika virus since January, 2015. In addition, five countries, including the U.S., have reported sexually transmitted Zika infections.

I have been writing about the problems of Zika for travelers for quite some time. In my April column, Take Zika virus seriously, even in the U.S., I explained,

“The Zika virus is primarily spread to people by bites by infected Aedes aegypti mosquitoes. Last week, the Centers for Disease Control and Prevention (CDC) posted new U.S. maps of a larger than previously estimated range the Aedes aegypti mosquito could reach this summer.”

Since then, new information has come to light which makes the threat for travelers in the Americas, including the U.S., potentially more serious.

While the Aedes aegypti mosquito only reaches as far north in the U.S. as southeastern Pennsylvania, all of New Jersey, New York City, southern Ohio, and San Francisco, it does cover nearly half the land area of the continental U.S. According to the Centers for Disease Control and Prevention (CDC), Zika can also be spread by the Aedes albopictus mosquito, which is found in all but 10 northern U.S. states.

Now, it’s been reported that Brazilian researchers at the Oswaldo Cruz Foundation have found another mosquito species, the Culex quinquefasciatus, infected with the Zika virus. Researchers at the Foundation previously reported the Culex quinquefasciatus could be infected with Zika, but now they have collected an infected mosquito of the species in the city of Recife.

Assuming this initial report is confirmed, it’s very troubling. Culex mosquitos are found in tropical and subtropical regions across the globe, as well as in temperate zones, such as in the U.S., where they are more common than the other varieties of mosquitoes carrying Zika. In the U.S., according to the American Mosquito Control Association, the country’s most common mosquitoes are Culex varieties. The Culex quinquefasciatus, commonly known as the “southern house mosquito,” is found in 28 U.S. states, according to the Invasive Species Compendium.

In addition to a new potential mosquito carrying the Zika virus throughout the Americas, the first case of sexual transmission of Zika from a woman to a man appears to have occurred in New York City, according to health officials.

Previously, scientists knew that men with Zika could pass it to female or male partners during unprotected sex, even if the man had no Zika symptoms. The virus remains active in semen longer than in blood. Assuming the new case is confirmed, we will then know that Zika is spread much like other sexually transmitted diseases. According to Dr. John Brooks, CDC expert on sexual transmission of Zika, the CDC is now updating its recommendations to include this new information.

These two discoveries are already requiring public health officials to rethink their vector control plans to control and contain Zika carrying mosquitoes. In the U.S. and elsewhere, the CDC and its counterparts are beginning to rewrite their warnings and instructions for Zika prevention based on the new data.

For travelers to Zika affected areas, the new information should raise their level of concern, require Zika prevention preparation for their journey, and push them to learn more about protecting themselves from becoming infected with the virus.

As it’s apparent that three varieties of mosquitoes can carry Zika — including one of the most common — more than ever, if you’re in an area where Zika can be spread by mosquitoes:

• Wear long-sleeved shirts and long pants whenever outdoors. Pull your socks over your pants legs to prevent mosquitoes from going under them.

• Use EPA-registered insect repellents proven safe and effective. The CDC recommends DEET- based insect repellents for mosquitoes. Use a repellent with a DEET concentration of 20 percent or more. Concentrations above 50 percent last longer.

Always follow the product’s use instructions and reapply as directed. If using sunscreen, apply the sunscreen before applying the repellent.

• Treat clothing and gear with permethrin-based insect repellents. Don’t use permethrin-based repellents directly on your skin, as they’re only intended to treat clothing.

• When camping, sleep under mosquito netting. Use mosquito netting for sleeping indoors if windows and/or doors without screening are open for ventilation.

At this time, the CDC is updating its warnings and instructions for the prevention of sexually transmitted Zika infection, so for sexually active travelers in Zika affected areas, I will anticipate their update as well as I can.

• Pregnant women and those attempting to become pregnant should consider postponing travel to Zika affected areas.

• Male partners of women attempting to become pregnant should also consider postponing travel to Zika affected areas.

• Men and women who have any possibility of being infected with Zika, whether or not they’re showing possible symptoms, should use precautions to prevent sexual transmission of Zika to their partner, such as a condom for men, not sharing sexual toys, not brushing teeth, which can promote bleeding prior to sexual relations, etc.

With the new information available about Zika, it’s essential travelers take all precautions necessary to prevent infection from mosquito bites, and if sexually active, use proper precautions meant for any sexually transmitted disease.

(Image: 2016 Map of U.S.A. of Range of Mosquitoes Transmitting Zika Virus, Copyright © 2016, NSL Photography. All Rights Reserved.)