Press release

From San Mateo County Health System: San Mateo County Has First Confirmed Case of Zika Virus

San Mateo, CA – Apr. 1, 2016

San Mateo County Health System today received confirmation from the California Department of Public Health that a San Mateo County resident has tested positive for Zika virus. The individual was infected with Zika virus while traveling abroad and is now fully recovered. No transmission of the disease took place in the United States, and there was no risk of the virus spreading to the local community from this case. To protect patient privacy, San Mateo County is not releasing further details about the confirmed Zika case.

“There is no reason for the general public to be concerned that they are at risk for getting Zika in San Mateo County at this time,” said Dr. Scott Morrow, San Mateo County Health Officer. “Zika virus is not circulating in our County and the few cases in California to date resulted from contracting the virus while traveling abroad. Taking precautions when traveling, based on CDC guidelines, is the best means of protection from Zika.”

The Zika virus is transmitted primarily by two species of mosquitoes, Aedes aegypti and Aedes albopictus. Zika virus is spread when a mosquito bites a person who has an active Zika virus infection and then bites another person. At this time there is no record of such a transmission occurring in the United States. The Aedes mosquito is mostly found in tropical countries, which currently include American Samoa, Brazil, Colombia, Costa Rica, Curacao, El Salvador, French Guiana, Guatemala, Haiti, Honduras, Martinique, Mexico, Nicaragua, Panama, Paraguay, Suriname, Venezuela and Puerto Rico.

While not native to San Mateo County, Aedes mosquito larvae were identified in Menlo Park in May 2015 by the San Mateo County Mosquito and Vector Control District. The District has been working to eradicate these mosquitos since first detecting them, and has been successful in their efforts—keeping the Aedes population very small and preventing their spread beyond Menlo Park. For more information visit

“Although there is no evidence in California of mosquitoes carrying Zika virus or of illnesses associated with the Aedes mosquito, people should always take steps to avoid mosquito bites,” stated Dr. Morrow. “This includes wearing insect repellent when necessary and removing standing water around homes and properties to keep mosquitoes from breeding. Residents should stay current on international travel alerts for countries where Zika virus is circulating, particularly women who are or may become pregnant.” San Mateo County Health System’s Communicable Disease Program staff issues updated advisories to local health care providers with information on how to identify and test for Zika virus.

For more Zika information and the latest guidance from the Centers for Disease Control and Prevention, visit

For more San Mateo County Health System Zika information, visit