Zika in King County: What it means and who should be concerned

Blood tests confirmed the first case of Zika virus in King County today in a man in his forties who had recently been in Colombia. This is the third case of Zika virus in the state of Washington, all found in people who became infected while in countries that have current Zika outbreaks. We caught up with Dr. Jeff Duchin, King County Health Officer, to find out what this means for people who live here.

Were you surprised that we’ve gone this long without having a case of Zika in our county?

JD: Yes, it was a little surprising, given the amount of international travel that passes through SeaTac. With ongoing widespread outbreaks in the Americas and the Caribbean including Puerto Rico, there have been over 400 Zika cases among travelers visiting or returning to the mainland United States. I expect that those numbers will continue to grow, including here in King County. And because many Zika cases are mild or without symptoms, there are likely more cases than get reported everywhere.

Could Zika spread from this one case to the wider public through local mosquitoes?

No, Zika cases in returning travelers to King County do not pose a risk of community Zika-Mosquito-icon spread locally. The kind of mosquitoes that can transmit Zika virus (from the species Aedes aegypti and Aedes albopictus) aren’t found in the Pacific Northwest. Even if a local mosquito bit someone who is infected, they wouldn’t pass the Zika virus.

What about through sexual transmission?

Zika virus can be spread from a recently infected man through sexual contact. This case and all men who test positive for Zika infection are counseled about measures to prevent sexual transmission.

It’s important for men who have traveled to an area with Zika to follow CDC’s guidance to prevent sexual transmission of Zika, even if they don’t feel sick. Many people who are infected don’t have any symptoms, so infected men could unknowingly spread the virus. Men and women should always take steps to prevent mosquito bites if they travel to Zika-affected areas.

What is the CDC learning about the health outcomes from Zika?

In most cases, illness from Zika is mild. Many people don’t have any symptoms, and when they do, they generally have fever, rash, joint pain, or red eyes.

For pregnant women and newborns, it’s a different matter. Strong evidence now shows that Zika virus can cause a birth defect called microcephaly, an abnormally small brain and skull. Zika has also been linked to other problems in newborns, such as eye defects, hearing loss, and impaired growth. So while Zika illness is usually pretty mild in most adults, it’s deeply concerning for pregnant women and their babies. Researchers are still investigating Zika infections during pregnancy. For example, we don’t know why some infected pregnant women have babies that are healthy and others have babies with birth defects.

A small proportion of Zika infections have been linked to Guillan-Barré Syndrome (GBS), which causes muscle weakness and sometimes paralysis. CDC is still investigating this, but it appears likely that Zika triggers GBS.

Should people in King County take any steps to prevent getting Zika?

Because we don’t have the mosquitoes that carry Zika here, we don’t need to take special measures to ward off mosquitoes because of Zika (although wearing repellant is recommended locally to prevent West Nile virus infections).

Zika is a serious risk for pregnant women who travel to areas where outbreaks are occurring and who have sex partners who have traveled to these areas. Women who are pregnant or who want to get pregnant should avoid travel to Zika-affected areas if possible and both women and men who do travel to areas where the Zika virus is spreading should take precautions to prevent infection from this virus. That means strictly following steps to prevent mosquito bites during the trip. Couples with men who live in or travel to areas with Zika can prevent the spread of Zika through sex by using condoms every time they have sex, or by not having sex during the risk period (see CDC site for details regarding duration of precautions). To be effective, condoms must be used consistently and correctly. The CDC has guidance on preventing sexual transmission.

If someone thinks they have Zika, how can they be tested?

If you have recently traveled to a Zika-affected area and experience symptoms of Zika, see your healthcare provider and tell your provider about your travel. We work with healthcare providers to determine whether individual patients potentially have Zika, based on the symptoms and travel itinerary. If your illness is consistent with Zika, your healthcare provider can order blood tests. It currently takes a few weeks to get results back because there are only a small number of labs at this time that can process Zika tests and there is a large volume of tests requested. However, in the past week the FDA approved a new type of commercial diagnostic test that can be ordered by healthcare providers for people who meet the CDC criteria for testing, so that may help reduce the waiting time in some cases.

Congress has been debating providing funding for Zika response in the U.S. What kind of work goes into Zika response at local health departments?

Local health departments are critical to the response of new disease outbreaks. Our communicable disease investigators, public health nurses, and epidemiologists:

  • work with healthcare providers to identify and investigate possible Zika cases that are reported,
  • work with state departments of health to provide diagnostic testing, and
  • follow-up with results and with counseling when needed for infected persons.

For example, in King County, although we just identified our first lab-confirmed Zika case, we have investigated over 200 cases of possible Zika infection, and made several other related diagnoses of mosquito-borne infections including dengue and chikungunya virus infections.

In areas that have the type of mosquitoes that can transmit the virus, local health departments also monitor mosquito populations and carry out mosquito control measures to prevent local spread. Health departments also keep healthcare providers and the public updated with the latest information and guidance on evaluating, diagnosing and preventing Zika virus infections.

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I am a risk communications specialist at Public Health - Seattle & King County.