Dr. Jeff Duchin, King County Health Officer, is at the CDC for the White House’s Zika Readiness Action Plan Summit to meet with other health officials to share the latest scientific knowledge about the Zika virus and discuss response strategies. We contacted him at the summit to ask him about the latest on Zika.

Why does Zika virus raise enough concern for a White House summit?

For most people, a Zika infection will only cause relatively mild illness, and in many cases, no symptoms at all. But it is a very serious health threat to pregnant women and newborns. There is sufficient evidence linking Zika infection to a birth defect called microcephaly, an abnormally small skull and brain. Researchers are also investigating other health problems for newborns infected with Zika and a possible link to Guillain-Barré syndrome, which can cause paralysis.

Zika virus is spreading in many parts of the world that have the Aedes species of mosquito that transmit the disease, including the U.S. territory of Puerto Rico. There is the potential for Zika to spread in states that have that type of mosquito. Washington State does not have the Aedes mosquito, so even though returning travelers from our area may be infected with Zika, we don’t expect local spread of the infection.  Because much of the US does have the mosquito that can transmit Zika, it’s important that we ready our national and local health systems now, before mosquito season, so that we can adequately track the spread of the virus and put measures in place to limit the mosquito populations.

What is the current research telling us about how Zika spreads?

The main way that Zika spreads is through mosquito bites, and only Aedes species mosquitoes have been shown to carry it. A pregnant woman, if infected, can also pass the virus to her fetus. Research has also sufficiently shown that Zika virus can be spread by a man through sexual transmission. So if a man travels to an area that has Zika and gets infected through a mosquito bite, he could then pass it to his partner through sex. For this reason, women who are pregnant or who are trying to become pregnant should be aware of the risk of infection from men who have been to Zika-affected areas and couples should take precautions to prevent Zika transmission.  At this time, testing men who have been to Zika-affected areas but did not have a Zika-like illness is not recommended.

Is it only men that can spread Zika virus through sex?

UPDATE, 2018: Both men and women can spread Zika through sex before symptoms start, when they have symptoms, and even after symptoms go away. That means that it may be possible for someone to carry Zika and give it to their sexual partners, even if they do not have symptoms or know that they are infected.

The CDC has guidance for couples with partners who live in or travel to areas with Zika to prevent Zika transmission through sex, including specific guidance for couples who are pregnant and those who are considering pregnancy.

If a woman gets infected with Zika before she is pregnant, will that endanger her future pregnancies?

All the available evidence right now suggests that a Zika infection in a woman who is not pregnant does not pose a risk to any future pregnancies after the virus has cleared from her blood.

What advice do you have for people who need to travel to an area where Zika virus is spreading?

If you are pregnant, avoid travel to an area with Zika if at all possible. If you must travel to one these areas, talk to your healthcare provider first and strictly follow steps to prevent mosquito bites:

• Wear long-sleeved shirts and long pants.
• Stay in places with air conditioning or that use window and door screens to keep mosquitoes outside.
• Use Environmental Protection Agency (EPA)-registered insect repellents. When used as directed, these insect repellents, including ones that have DEET, are proven safe and effective even for pregnant and breastfeeding women.
• Remove or stay away from mosquito breeding sites, like containers with standing water.

Because sexual transmission is possible, people traveling to an area with Zika should follow the same steps to prevent mosquito bites.

Is there any Zika spreading in the United States or Washington State?

No, not in the mainland United States or Washington. There are cases of Zika in the U.S. in individual travelers who have been to areas with Zika, but none who have become infected in the United States. Zika is spreading in Puerto Rico, American Samoa, and the U.S. Virgin Islands. As mosquito season starts in states where the Aedes mosquito lives, it’s possible for Zika to spread in those areas—we’re talking about how to limit that possibility at the Zika Action Plan Summit. We don’t expect a risk for Zika to spread in the Pacific Northwest because we don’t have that type of mosquito.

If I’m pregnant, should I avoid travel to places in the U.S. that have the type of mosquito that can carry Zika?

At the time of any travel, it’s a very good idea for pregnant women to check on the status of Zika both in the U.S. and internationally by visiting the CDC’s Areas with Zika web site, talk with their healthcare provider and avoid travel to areas where Zika transmission is active. Because Zika is NOT circulating in the U.S. at this time, the CDC does not have any advisories for travelers to mainland U.S. states.

As mosquito season starts in other parts of the country, it’s possible that we could see cases of Zika acquired in the U.S. in areas that have the mosquito that can transmit Zika. However, even if individual cases of local transmission occur in mainland U.S., widespread or sustained transmission is unlikely. In general, if you travel to areas where mosquitoes are present in the US, it’s always a good idea to take steps to prevent mosquito bites (the same mosquitoes that transmit Zika could carry dengue fever or West Nile virus in the many areas where those disease occur.

Is there a vaccine for Zika?

No. The CDC and its research partners are working on development of one, but it will probably be at least a couple of years before one would be ready.

Originally posted in April, 2016. More information on Zika: kingcounty.gov/zika