Zika Virus Disease
Zika virus disease is an infectious disease which the World Health Organization has declared is a Public Health Emergency of International Concern. Zika is primarily spread through mosquito bites (Aedes aegypti and Aedes albopictus), but it can also be:
- Transmitted through sex (i.e., anal, oral and vaginal sex; and sharing sex toys)
- Passed from pregnant women to their babies during pregnancy and birth
- Spread in other ways, including blood transfusions and tissue and organ transplants
Most individuals (about 80%) infected with Zika virus don't develop symptoms or know they are infected. When symptoms do occur they may include:
- Muscle or joint pain
- Conjunctivitis (red eyes)
- Headache — especially with pain behind the eyes
Although most of those infected with Zika virus infection will not experience noticeable symptoms, there are very significant risks associated with the disease.
According to the Centers for Disease Control and Prevention, Zika virus infection causes serious birth defects and negative pregnancy outcomes, including miscarriage, microcephaly and other "severe fetal brain defects." Microcephaly is a condition in which a baby's head and brain are underdeveloped and smaller than expected. Microcephaly can result in intellectual disabilities, hearing and vision problems, seizures, and other health concerns. Important information for pregnant women is available through the Centers for Disease Control and Prevention.
In addition, with increased numbers of neurological conditions occurring in outbreak areas, questions have been raised about a potential connection between Zika virus and Guillain-Barré syndrome and other neurological disorders.
Unlike some infections, there is no vaccine against Zika virus, nor is there a specific medication to treat the infection.
Outbreak Locations and Travel Safety
Historically, Zika virus outbreaks have occured in Africa, Southeast Asia and the Pacific Islands. Zika made its first appearance in the Americas (Brazil) in 2015 and has since spread throughout various regions of Central and South America, Mexico, and the Caribbean.
Zika Travel Notices
Travelers (especially pregnant women, women who are planning pregnancy, and the sex partners of either) should take note of the Centers for Disease Control and Prevention (CDC) Zika Travel Notices* in effect for regions with local Zika virus transmission, including areas in:
- Central America
- Pacific Islands
- South America
- And countries with endemic Zika
Note: The CDC currently recommends that pregnant women not travel to areas with Zika!
If you will be traveling to a location with local Zika transmission, reduce your risk of mosquito bites by using insect repellent, turning on the air conditioner in your hotel room, keeping windows and screens closed, and wearing long-sleeved shirts and long pants. If you are pregnant or trying to become pregnant, or you are a sex partner of either, consult with a healthcare provider prior to travel. Additional tips can be found through the Centers for Disease Control and Prevention's Plan for Travel.
If you have recently travelled to an area with local Zika transmission, the CDC recommends watching for fever, headache, joint pain, muscle pain, conjunctivitis, or a rash appearing within two weeks of travelling. See a doctor or other healthcare provider if you become ill and inform them where you traveled. Pregnant women who have recently traveled to an area with Zika should talk to their doctor about their travel even if they have no symptoms of Zika virus disease. All individuals who have traveled to an area with Zika should also prevent mosquito bites for at least three weeks after returning from travel and follow CDC recommendations to prevent sexual transmission of Zika virus (also see the California Department of Public Health's Zika + Sex).
Preventing Zika Virus Infection
For comprehensive Zika prevention information, visit the Centers for Disease Control and Prevention.
Prevent Mosquito Bites | Prevent Infection During Pregnancy | Prevent Infection when Trying to Get Pregnant | Prevent Sexual Transmission | Prevent Infection After Travel | Prevent Infection if You're Sick with Zika
The mosquitoes which transmit Zika virus not only bite during the night, they are aggressive daytime biters. These mosquitoes also spread chikungunya virus and dengue virus.* You can help protect yourself and others against mosquito bites by strictly following mosquito bite prevention guidelines, which include:
- Eliminating standing water (e.g., water in toys, flower pots, trash containers, etc.) in and around your home on a weekly basis by emptying, scrubbing (mosquito eggs stick to containers), turning over, covering, or throwing out items.
- Using air conditioning
- Using screens on windows and doors
- Correctly using an Environmental Protection Agency-registered insect repellent
- Note: Some repellents (e.g., oil of lemon eucalyptus) have age-related safety restrictions. General insect repellent use and safety information is available, but always carefully follow specific insect repellent instructions for use on babies and children.
- Wearing long sleeves
- Treating clothing and gear with permethrin according to product instructions
- Covering cribs, strollers and baby carriers with mosquito netting
- Sleeping under a mosquito bed net
*Visit the California Department of Public Health or see "Other Mosquito-Borne Infections" in the "Resources" section of this page for information on chickungunya and dengue infections in Mexico, Central and South America, and the Big Island of Hawai‘i.
- Pregnant women — no matter what trimester — should not travel to areas where Zika virus is spreading. Refer to the Centers for Disease Control and Prevention's Information for Pregnant Women and Zika Travel Notices for the most up-to-date information.
- Pregnant women who have traveled to an area with local Zika virus transmission are advised to talk to their healthcare providers about their travel even if they don't have infection symptoms.
- Correctly use condoms and other barriers (e.g., latex dams) from start to finish every time you have sex or don't have sex for the duration of the pregnancy.
- Avoid sharing sex toys during pregnancy.
- Women trying to get pregnant and their sex partners should talk to their healthcare providers before traveling to an area with local Zika virus transmission, and take precautions to prevent mosquito bites.
- Consult a healthcare provider if one or more partners have traveled to (or lives in) an area with Zika.
Individuals infected with the Zika virus can spread Zika to their sex partners during anal, oral and vaginal sex, and through sharing sex toys — even when they don't have symptoms. Zika virus can be found in semen, vaginal secretions, blood, urine, and other body fluids — remaining in semen longer than other body fluids. Abstinence (not having sex) is the best way to prevent sexual transmission of Zika virus.
Those at risk (travel to or living in an area with Zika) should follow the latest Centers for Disease Control and Prevention guidelines for preventing sexual transmission of Zika virus which include:
Correctly using condoms and other barriers (e.g., latex dams) from start to finish every time you have sex or don't have sex.
To prevent Zika virus infection transmission after travelling to an area with local Zika virus transmission:
- Prevent mosquito bites for at least 3 weeks after travel
- Zika virus can remain in the blood of an infected person for a week or more. If the infected person is then bitten by a mosquito that mosquito may become infected with the Zika virus and then go on to infect other individuals it bites.
- Abstain from sex (including sharing of sex toys) or correctly use condoms and other barriers (e.g., latex dams) from start to finish every time you have sex
- Refer to the latest Centers for Disease Control and Prevention guidelines for preventing sexual transmission of Zika virus for additional information (e.g., timeframes for using condoms or abstaining from sex), especially with regards to pregnancy safety precautions.
If you develop Zika virus infection symptoms — fever, rash, muscle or joint pain, headache (especially with pain behind the eyes), and conjunctivitis — see your doctor and protect yourself against mosquito bites. Beause Zika virus can remain in the blood of an infected person for a week or more, it is very important for infected individuals to prevent being bitten by mosquitoes which can then go on to infect family, friends and others.
Resources | References
For additional information and prevention strategies, please see these resources:
- Centers for Disease Control and Prevention
Fact Sheets and Infographics
- Frequently Asked Questions: Zika Virus Disease (Links to LADPH)
- This fact sheet is also available in Chinese, Japanese, Korean, Spanish, Tagalong, Thai, and Vietnamese through the LADPH
- How to Protect Against Mosquito Bites (Links to CDC)
- Keep Mosquitoes Out of Your Septic Tank (Links to CDC)
- Mosquito Bite Prevention (United States) (Links to CDC)
- Mosquito Life Cycle (Links to CDC)
- Protect Yourself from Mosquito Bites (Links to CDC)
- Sick with Chikungunya, Dengue, or Zika? (Links to CDC)
- The Right Way to Use a Male Condom (Links to CDC)
- Pregnant? Protect Yourself from Mosquito Bites (Links to CDC)
- Pregnant? Read This Before You Travel (Links to CDC)
The Right Way to Use a Male Condom (Links to CDC)
- Zika Prevention Kit for Pregnant Women (Links to CDC)
- How to Protect Yourself from Getting Zika from Sex (Links to CDC)
- Zika and Sexual Transmission (Links to CDC)
- Mosquito Bite Prevention for Travelers (Links to CDC)
- Spring Break on Your Mind? (Links to CDC)
The Right Way to Use a Male Condom (Links to CDC)
- Chickungunya (Links to LADPH)
- Dengue Fever (Links to CDPH)
- West Nile Virus (Links to LADPH)
- Additional resources (Links to CDPH)
Centers for Disease Control and Prevention. (no date). Recently in the American tropics? Retrieved from http://www.cdc.gov/chikungunya/pdfs/arbovirus_inbound_11x14_508.pdf.
Centers for Disease Control and Prevention. (2015). Help control mosquitoes that spread dengue, chikungunya, and Zika viruses. Retrieved from http://www.cdc.gov/zika/pdfs/control_mosquitoes_chikv_denv_zika.pdf.
Centers for Disease Control and Prevention. (2016). Facts about microcephaly. Retrieved from http://www.cdc.gov/ncbddd/birthdefects/microcephaly.html.
Centers for Disease Control and Prevention. (2016). Mosquito bite prevention for travelers. Retrieved from http://www.cdc.gov/chikungunya/pdfs/fs_mosquito_bite_prevention_travelers.pdf.
Centers for Disease Control and Prevention. (2016). Prevent mosquito bites. Retrieved from http://www.cdc.gov/zika/prevention/prevent-mosquito-bites.html.
Centers for Disease Control and Prevention. (2016). Question and answers: Zika virus infection (Zika) and pregnancy. Retrieved from http://www.cdc.gov/zika/pregnancy/question-answers.html.
Centers for Disease Control and Prevention. (2016). Zika and sexual transmission. Retrieved from http://www.cdc.gov/zika/transmission/sexual-transmission.html.
Centers for Disease Control and Prevention. (2016). Zika prevention. Retrieved from http://www.cdc.gov/zika/prevention/index.html.
Kindhauser, M.K., Allen, T., Frank, V., Santhana, R., and Dye, C. (2016). Zika: the origin and spread of a mosquito-borne virus. Retrieved from http://www.who.int/bulletin/online_first/16-171082/en/.
Pan American Health Organization. (2016). Zika and sexual transmission. Retrieved from http://www.who.int/features/qa/zika-sexual-transmission/en/.