HOW DO I?
Certain regions of Latin America and the Caribbean have experienced a significant increase in Zika infections in 2015‐2017. If you are traveling to an area with Zika, the California Department of Public Health recommends taking appropriate precautions for avoiding mosquito bites during the day and at night. Pregnant women are advised not to travel to regions where there is Zika virus transmission.
Since the emergence of Zika in Brazil in 2015, Zika virus has spread rapidly throughout Latin America and the Caribbean. Currently, Zika outbreaks are ongoing in 61 countries and territories, including in Mexico, where the highest numbers of cases are in the southern part of the country. However, the U.S. Centers for Disease Control and Prevention considers any travel to Mexico to be a risk for Zika infection. Individuals have been infected in popular tourist destinations including Cancun, Acapulco, Cabo San Lucas, Puerto Vallarta, Ixtapa, Mazatlan, and most recently, Ensenada, a coastal city in Baja Norte California. Local Zika virus transmission in Baja California Norte increases the risk that California residents will be exposed to the virus due to travel across the border. In addition, identification of local Zika virus transmission in Baja California increases the risk for local transmission in California due to the high volume of travel across the Mexico‐California border daily and the presence of Aedes mosquitoes on both sides of the border. Active Zika virus transmission in the United States and U.S. territories has only been identified in Miami‐Dade County in Florida, Cameron County in Texas, Puerto Rico, U.S. Virgin Islands, and American Samoa.
Zika virus infection during pregnancy can cause a serious birth defect called microcephaly, as well as other severe fetal brain defects and poor pregnancy outcomes. Zika virus infection has also been
tied to Guillain‐Barré Syndrome, a rare disorder that can cause muscle weakness and paralysis. Although primarily transmitted by mosquitoes, Zika virus can also be sexually transmitted.
Zika is transmitted by Aedes aegypti and Aedes albopictus mosquitoes. These two mosquitoes are aggressive day‐biters that can potentially transmit the virus after biting an infected person. These mosquitoes typically develop in small, water‐filled containers. The presence of Aedes aegypti has been established in Mexican cities along the California‐Mexico border, such as Mexicali, Tecate, and Tijuana. In California, Aedes aegypti and Aedes albopictus mosquitoes have been detected in numerous California counties, including along the border in San Diego and Imperial counties.
Reported Zika Cases in California
As of February 2017, the number of reported Zika cases among travelers returning from Zika‐affected areas continues to increase in California. Since the ongoing Zika virus outbreak in Latin America began in 2015, there have been more than four hundred travel‐associated Zika virus infections in California.
Zika Virus Transmission
Zika virus is transmitted to people primarily through the bite of an infected Aedes species mosquito.
Transmission has also been reported through sexual contact with an infected person, from a pregnant woman to her fetus, through blood transfusion, and through laboratory exposure.
Zika Clinical Presentation
Most people infected with Zika virus have no symptoms. If symptoms develop, the most common are fever, rash, joint pain, and/or red eyes. Symptoms usually begin a few days to a week after being bitten by an infected mosquito or having unprotected sex with an infected partner. The illness is usually mild with symptoms lasting for several days to a week. However, Zika virus infection during pregnancy can cause serious birth defects. Pregnant women should not travel to Zika‐affected areas. Additionally, pregnant women should abstain from sex or use condoms with partners who have traveled to an area with Zika for the duration of the pregnancy.
If you are traveling to an area with Zika virus transmission, the California Department of Public Health
recommends taking steps to avoid mosquito bites during the day and at night. If you have returned from an area with Zika and have fever with joint pain or rash within the two weeks following your return, please contact your health care provider and say where you have traveled, and use mosquito repellent for three weeks following your return.
There are no vaccines to prevent Zika. Preventing mosquito bites is the best way to avoid becoming infected.
- 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 andthen the repellent.
- When weather permits, wear long‐sleeved shirts and long pants.
- Use air conditioning or window/door screens to keep mosquitoes outside. If you are unable to protect yourself from mosquitoes inside your home or hotel, sleep under a mosquito bed net.
- Help reduce the number of mosquitoes outside your home or hotel room by emptying standing water from containers such as flowerpots or buckets.
Important Information for Pregnant Women
Pregnant women should take special precautions to protect themselves from Zika virus.
- If you are pregnant, do not travel to areas with Zika.
- If you are pregnant and must travel, talk to your healthcare provider before traveling, and strictly follow steps to avoid mosquito bites during your trip.
- Because sexual transmission of Zika is possible, pregnant women whose partners have traveled to an area with Zika should either not have sex, or use condoms consistently and correctly for the duration of the pregnancy.
- If you are pregnant and were potentially exposed to Zika (either through travel to an area with Zika or through unprotected sex with someone who traveled to an area with Zika), talk to your healthcare provider regardless of whether or not you have Zika symptoms.
More Information for Clinicians
More information on the clinical presentation, epidemiology, and diagnostic criteria for Zika is available in the following California Department of Public Health resources: Zika Virus FAQs for Health Care Providers and Zika Virus Testing FAQs for Health Care Providers.
What you can do to reduce the risk of Zika infection:
How to protect yourself from mosquito bites:
Information on invasive Aedes mosquitoes in California: