Zika Virus


Courtesy of CDC, 2006

What is the Zika virus?

Zika virus is a mosquito-borne virus that prior to 2015 occurred in Africa, Southeast Asia, and the Pacific Islands. However, in May 2015, the Pan American Health Organization (PAHO) issued an alert about the first confirmed Zika virus infections in Brazil. Since then Zika virus has been identified in several countries throughout South and Central America, and the Caribbean. No mosquito-transmitted Zika virus cases have been reported in San Diego County, but there has been a sexually-transmitted case in the region, as well as cases reported in returning travelers.


How Is It Spread?

Zika virus is spread by the bite of an infected Aedes species mosquito, which actively bite humans during the daytime. These are the same mosquitoes that spread dengue, chikungunya, and yellow fever viruses. Mosquitoes become infected when they feed on a person already infected with the virus. Infected mosquitoes can then spread the virus to other people through bites. Zika virus is rarely spread from person to person; there have been rare instances of sexual and perinatal (mother-to-child) transmission as well as through blood transfusion.

What Are the Symptoms?

Symptoms begin between 2 and 12 days (most commonly 3-7 days) after exposure to the virus. Although most people who become infected with Zika virus have no symptoms, approximately 20% may develop acute onset of fever with rash, joint pain, or conjunctivitis (red eyes). Other commonly reported symptoms include muscle aches and headache that may last for several days to a week. Severe disease requiring hospitalization is uncommon and deaths from the disease are rare. However, there have been cases of Guillain-Barré syndrome reported in patients following suspected Zika virus infection. Some babies with microcephaly (abnormal brain and small heads) have been reported among mothers who were infected with Zika virus while pregnant. In April 2016, CDC scientists announced that enough evidence has accumulated to conclude that Zika virus infection during pregnancy is a cause of microcephaly and other severe fetal brain defects.

What Can You Do?

The public should continue to remember the  “Prevent, Protect, Report” slogan that has guided the County’s fight against West Nile virus.

Prevent mosquito breeding sites. Every week, dump out and clean containers that hold water inside and outside homes. Fill plant saucers with sand or fine gravel so water won’t form pools where mosquitoes can breed.

Protect yourself from mosquito bites. Wear long sleeves and pants when outdoors. Use insect repellent, preferably one containing DEET. Make sure the screens on your windows and doors are in good condition, do not have holes or tears, and are secured to keep insects out.

Report if you are being bitten by mosquitoes during daylight hours, or if you find mosquitoes that match the description of the yellow-fever mosquito or Asian tiger mosquito.


Latest Update on the Zika Virus

For the latest, updated information on the Zika Virus, please see Frequently Asked Questions – Zika Virus and Mosquitoes  San Diego County – October 2016



The websites and resources below provide additional information to community members and medical providers regarding  Zika virus.    

Information for the Public

Resources for Healthcare Providers

County of San Diego




CDC Information about Other Diseases Carried by Aedes Mosquitoes


For more information, contact the Epidemiology Program 619-692-8499 or send us an e-mail.