Zika is a virus that spreads through the bite of certain types of mosquitoes. If infected while pregnant, a mother can pass Zika to her unborn child. Zika infection during pregnancy can cause birth defects and developmental delays. Zika virus can also be passed through sex and blood transfusions.
While the virus can cause mild symptoms, about 80 percent of people with Zika do not have any symptoms at all. Severe disease requiring hospitalization is uncommon and fatalities are rare. Although uncommon, Zika virus may also be among the causes of Guillain-Barré syndrome, a condition in which your immune system attacks part of your nervous system.
Mosquito bites are the primary way that Zika virus is spread. The virus can also be passed from a pregnant woman to her unborn child, if the mother is infected during pregnancy. Additionally, a person with Zika can pass it to his or her sex partners. There have not been any reports of pets or other kinds of animals spreading or becoming infected with Zika.
Not all mosquito types transmit Zika virus. It is primarily transmitted through the bite of an infected Aedes mosquito (Aedes aegypti and possibly Aedes albopictus). These mosquitoes are found throughout Texas and can be active year-round in parts of South Texas that experience mild winters. They typically lay eggs on the walls of water-filled containers like buckets, bowls, animal dishes, flower pots, and vases. They live indoors and outdoors and are most active between dawn and dusk.
Infected people can transmit Zika virus to mosquitoes even if they’re not sick. If a mosquito takes a blood meal from an infected person, after seven to 10 days, it can pass Zika virus to other people it bites.
Although some cases of local transmission have been reported in Texas, most Texas cases of Zika are related to travel. These travel-related cases involve people who were bitten by an infected mosquito while traveling to an area where Zika is being spread and then diagnosed after returning home.
Many people infected with Zika will have no symptoms or mild symptoms that last several days to a week. However, Zika infection during pregnancy can cause a serious birth defect called microcephaly and other severe birth defects. Current research suggests that Guillain-Barré syndrome, an uncommon sickness of the nervous system, is associated with Zika; however, only a small proportion of people with recent Zika virus infection get GBS.
Once someone has been infected with Zika, it’s very likely they’ll be protected from future infections. There is no evidence that past Zika infection poses an increased risk of birth defects in future pregnancies.
While many with Zika do not have any symptoms, the virus can cause fever, rash, joint pain, and conjunctivitis (red or pink eyes) lasting a few days to a week. Read more on our Symptoms page.
To diagnose Zika, your doctor will ask you about recent travel and symptoms you may have, and may collect blood and urine to test for Zika or similar viruses.
No. Currently, there is no vaccine or specific treatment for Zika virus.
Your best protection is to avoid infection:
- Prevent mosquito breeding.
- Protect yourself from mosquito bites.
- Wear Environmental Protection Agency (EPA)-registered insect repellents while outside.
- Protect against sexual transmission.
- Use barrier contraceptive methods, such as condoms, consistently and correctly during sex or abstain from sex.
If you have Zika, it's important to protect others from getting sick by avoiding mosquito bites and by following the U.S. Centers for Disease Control and Prevention (CDC) guidance for prevention of sexual transmission and advice for Women & Their Partners Trying to Become Pregnant.
For more details on how to prevent Zika, see our Prevention page.
Use Environmental Protection Agency (EPA)-registered insect repellents. When used as directed, these insect repellents—including those that contain DEET—are proven safe and effective even for pregnant and breastfeeding women.
Do not apply insect repellent onto a child’s hands, eyes, mouth, or to a cut or irritated skin. Instead, spray an EPA-registered insect repellent onto your hands and then apply it to a child’s face. Cover cribs, strollers, and baby carriers with mosquito netting for babies under two months.
Texas covers certain mosquito repellent products for the prevention of Zika virus as a benefit of Medicaid and other state programs. To find out if you are eligible, and for more information, see the Mosquito Repellent Available as a Statewide Benefit page on the Texas Health and Human Services website.
Areas with Zika Infection Risk
No. The U.S. Centers for Disease Control and Prevention (CDC) recommends that pregnant women should not travel to areas with Zika infection risk. Talk to your doctor if you live in an area with Zika risk and are pregnant or planning to become pregnant.
People who live in or are traveling to areas where Zika is being spread should take steps to prevent mosquito bites and sexual transmission of Zika.
Texans who live along the Texas-Mexico border—particularly those who are pregnant—should be especially cautious to prevent mosquito bites and protect themselves from sexual transmission of Zika virus.
Testing & Treatment
On April 2, 2018, the Texas Department of State Health Services (DSHS) updated its testing guidance for pregnant women in Texas:
- Pregnant women who live in Cameron, Hidalgo, Kinney, Maverick, Starr, Val Verde, Webb, Willacy, and Zapata counties should be tested three times during pregnancy (using PCR only).
- Elsewhere in the state, pregnant women with no symptoms but recent possible exposure (for example, women who have traveled to areas with ongoing Zika transmission) should be tested as soon as possible up to 12 weeks after exposure.
The guidance for testing non-pregnant residents remains the same:
- Residents of the nine higher-risk counties with a rash plus one other common Zika symptom (fever, joint pain or conjunctivitis) should be tested.
- Residents of other parts of the state with three or more Zika symptoms should be tested.
- Any non-pregnant resident with Zika symptoms starting within two weeks of travel to an area with ongoing Zika transmission or sexual contact with a traveler to an area with ongoing transmission should be tested.
There is no specific treatment or vaccine for Zika virus. However, if you feel sick and are concerned you may have been exposed to Zika, visit your doctor and treat your symptoms accordingly. To feel better, get plenty of rest and drink a lot of fluids. While you are sick, as well as after the virus has left your body, you should continue to follow Zika prevention precautions such as using EPA-approved insect repellent and taking steps to prevent sexual transmission of the virus.
Zika & Pregnancy
Currently, there is no evidence that a woman who has recovered from Zika virus infection (the virus has cleared her body) will have Zika-related pregnancy complications in the future. Based on information about similar infections, once a person has been infected with Zika virus and has cleared the virus from his or her body, he or she is likely to be protected from future Zika infections.
If you are pregnant or planning on becoming pregnant, talk to your doctor about any possible exposure to Zika that you or your sex partner may have had. Pregnant women living in Texas—particularly along the Texas-Mexico border—should be especially cautious to protect against mosquito bites and sexual transmission of Zika.
Although Zika virus has been detected in breast milk, there are no reports of health problems in babies tied to breastmilk from an infected mother. Current evidence suggests the benefits of breastfeeding outweigh the theoretical risks of Zika virus transmission.
Zika in Texas
Most of Texas has a long mosquito season, and the mosquitoes that transmit Zika can be found throughout the state. Also, many Texans travel to places where Zika is being spread. This increases the risk of Texas mosquitoes picking up the virus and spreading it in Texas communities.
Local mosquito-borne spread of Zika has been reported in the continental United States, including in places along the Texas-Mexico border. The Texas Department of State Health Services (DSHS) urges Texans who live along the Texas-Mexico border to remain on alert for Zika and to continue to take precautions against mosquito breeding and mosquito bites year-round.
Texas has made significant progress in its efforts to minimize the impact of Zika on the state. While local transmission has occurred in Texas, public health officials do not expect widespread transmission across large geographic areas. Small pockets of cases in limited clusters continue to be possible. This assessment is based on the patterns with Zika and dengue, a similar virus spread by the same mosquitoes.
The Texas Department of State Health Services (DSHS) is the lead state agency preparing for, coordinating, and responding to public health and medical incidents involving Zika virus. For emergency preparedness and response, DSHS operates within the overall context of emergency management in Texas, and in conjunction with local, state, and federal partners. Local health departments throughout Texas also play a key role in preparing for and responding to the impacts of Zika virus in their communities, including addressing local mosquito surveillance and control measures.
The Zika Virus Preparedness and Response Plan describes what actions DSHS may take to successfully respond to Zika. It follows a phased approach and includes specific response activities for local transmission.
Learn more on our Zika Response page.
There are two categories of Zika tests to determine if your patient may have Zika virus infection: molecular tests and serologic antibody-detection tests (see the CDC’s Types of Zika Virus Tests for additional details). Molecular tests, commonly known as nucleic acid testing (NAT) or polymerase chain reaction (PCR), test for Zika virus RNA. Zika virus RNA may be detected in serum and urine early in the course of the infection, and in some instances, pregnant women can have detectable Zika virus RNA in specimens collected many weeks after initial exposure. Zika virus-specific IgM antibodies typically develop within the first 3-5 days after infection, and Zika virus-specific neutralizing antibodies develop approximately one week after infection. Zika IgM is usually detectable for at least 12 weeks, and sometimes much longer.
Zika virus PCR is most appropriate for symptomatic individuals with possible Zika exposure who have developed symptoms of Zika disease within the previous week and for asymptomatic pregnant women with possible Zika exposure. DSHS recommends that Zika virus PCR testing be performed on paired urine and serum specimens when possible. Doing so maximizes the sensitivity of the testing, since persistence of viral RNA in various body fluids is not uniform. Serum specimens can be tested without a paired urine specimen, but urine specimens cannot be tested without a paired serum specimen.
For individuals with Zika exposure and Zika symptoms, serologic tests to detect an IgM antibody response to Zika infection should be used alongside PCR to help ensure that a possible Zika infection is detected. Given the potential for Zika IgM to remain elevated for longer than 12 weeks, a positive Zika IgM result may reflect a previous Zika infection if the individual was exposed in the past. Positive Zika IgM test results may also reflect cross-reaction with related viruses called flaviviruses, including dengue virus or West Nile virus.
Positive, equivocal, and inconclusive Zika IgM results require confirmatory testing at a designated public health laboratory, usually the Centers for Disease Control and Prevention (CDC). Confirmatory testing includes the Plaque Reduction Neutralizing Test (PRNT), a more specific method to accurately identify to which virus(es) the patient’s antibodies have responded. PRNT reflects the total neutralizing antibody response to each virus tested and does not reflect the timing of infection. IgM and PRNT results are interpreted together with the patient’s exposure and symptomology to determine whether recent Zika infection may have occurred.
To submit a specimen for Zika testing at one of the Texas Department of State Health Services (DSHS) public health laboratories, make sure to follow the specimen collection and shipping instructions detailed in the Chikungunya, Dengue, and Zika PCR and Serology Specimen Criteria guidance document. All specimens submitted for testing at DSHS public health laboratories require appropriate test request form(s) and supplemental information form(s) to be included with the shipment. Serum is generally a required specimen for Zika testing, and other specimen types may be tested alongside the serum, including urine or cerebrospinal fluid (CSF).
DSHS recommends testing for specific groups with potential exposure to Zika. If you are unsure whether your patient meets the recommended testing criteria for DSHS, please contact your local health department or DSHS public health region for assistance. Note that Zika testing at commercial laboratories is widely available, though these tests may require follow-up testing at a public health laboratory to confirm any preliminary positive results.