California Department of Public Health (CDPH) Director and State Public Health Officer Dr. Karen Smith today advised that although there is no evidence of mosquitoes carrying Zika virus in California, people should always take steps to avoid mosquito bites, including removing standing water and wearing insect repellant when necessary. Californians should also be advised of international travel alerts for the countries where Zika virus is circulating. 

“Although no one has contracted Zika virus in California, mosquito bites can still be harmful and the public should take steps to protect themselves,” said Dr. Smith. “Help reduce the risk of mosquito bites by removing standing water from around your home and wearing mosquito repellant when appropriate.”  

As of Jan. 29, 2016, there are six confirmed cases of Zika virus in California, all of which were contracted when traveling in other countries with Zika virus outbreaks in 2013 (1), 2014 (3) and 2015 (2). CDPH will continue monitoring for any confirmed cases in California and will provide weekly updates every Friday. To protect patient confidentiality, specific locations of infected patients cannot be disclosed.   

Zika virus is primarily transmitted to people by Aedes aegypti and Aedes albopictus mosquitoes, the same mosquitoes that can transmit dengue and chikungunya viruses. These mosquitoes — which are not native to California — have been identified in 12 California counties, although there are no known cases where the mosquitoes were carrying the Zika virus in this state. The six confirmed cases of Zika virus in California were acquired in other countries.

The Centers for Disease Control and Prevention (CDC) have issued a travel alert (Level 2-Practice Enhanced Precautions) for people traveling to regions and certain countries where Zika virus transmission is ongoing: American Samoa, Brazil, Colombia, Costa Rica, Curacao, El Salvador, French Guiana, Guatemala, Haiti, Honduras, Martinique, Mexico, Nicaragua, Panama, Paraguay, Suriname, Venezuela and Puerto Rico.

People traveling to these and other countries with known Zika virus risk should take steps to avoid being bitten by mosquitoes, including:

Use insect repellents containing DEET, picaridin, IR3535, oil of lemon eucalyptus, or para-menthane-diol for long lasting protection. If you use both sunscreen and insect repellent, apply the sunscreen first and then the repellent. Pregnant women and women who are breastfeeding can and should choose an EPA-registered insect repellent and use it according to the product label

Wear long-sleeved shirts and long pants

Use air conditioning or window/door screens to keep mosquitoes outside. If you are not able to protect yourself from mosquitoes inside your home or hotel, sleep under a mosquito bed net

Help reduce the number of mosquitoes outside by emptying standing water from containers such as flowerpots or buckets

The CDC and CDPH have also issued guidance for pregnant women recommending they avoid countries where Zika virus is circulating. Pregnant women who cannot avoid travel to these countries should talk to their health care provider and take steps to avoid mosquito bites. The CDC and CDPH have also provided guidance for physicians on the evaluation of pregnant women and infants who may have been exposed to Zika virus.

Most people infected with Zika virus will not develop symptoms. If symptoms do develop, they are usually mild and include fever, rash and eye redness. If you have returned from an affected country and have fever with joint pain, rash within two weeks, or any other symptoms following your return; please contact your medical provider and tell the doctor where you have traveled. While there is no specific treatment for Zika virus disease, the best recommendations are supportive care, rest, fluids and fever relief.

There is concern that Zika virus may be transferred from a pregnant woman to her baby during pregnancy or delivery. Preliminary reports suggest that Zika virus may cause microcephaly (abnormal fetal brain development). This possibility has not been confirmed and is being actively investigated. CDPH has requested that health care providers report suspected Zika virus disease or associated conditions of microcephaly to local health departments. Local health departments will report cases to CDPH, which is coordinating referral of any specimens to CDC for diagnostic testing.

For more information on Zika virus disease and other mosquito-borne illnesses, please visit the CDPH Zika virus information webpage.