Key points about Zika virus
- Many countries and parts of the continental U.S. have been identified as areas of possible Zika virus transmission. Since 2016, the number of cases reported from Latin America and the Caribbean has fallen dramatically.
- Dengue virus currently is causing large outbreaks in many areas of the world, with low to no Zika virus transmission being reported globally.
- Zika can be spread through mosquito bites, from mother to child, via unprotected sexual contact, or through blood transfusion or laboratory exposure.
- 80% of individuals with Zika infection are asymptomatic.
- Regardless of symptoms, people with Zika virus infection can transmit the virus to others.
- Zika virus testing is available through commercial laboratories. Concurrent dengue testing is recommended for symptomatic individuals given the changing epidemiology.
- Advise patients to avoid mosquito bites and use condoms or abstain from sex following return from a Zika-affected area.
Zika Virus (Diseases A-Z)
On this page:
Zika infection is reportable in Oregon. Healthcare providers are required to report suspect, presumptive, and confirmed Zika virus infections to local health department in the patient's county ofo residence within one day (call the "CD Nurse" Communicable Disease number).
As of January 1, 2019 the Oregon State Public Health Laboratory does not perform Zika testing.
Many commercial laboratories offer Zika testing options. Zika IgM testing is no longer recommended because IgM antibodies can cross-react with other flaviviruses like dengue and can persist for months following infection, so they may not be indicative of a recent infection. Providers should refer to their clinical laboratory for guidance on specimen collection and transport when sending Zika testing to commercial laboratories.
Zika testing is recommended for:
- Individuals, including pregnant women, who have at least one symptom of Zika (fever, rash, joint pain, or conjunctivitis) and possible Zika virus exposure defined as
- recent travel to
an area with risk of Zika or
- unprotected sexual contact with someone who recently traveled to an area with risk of Zika.
- Pregnant women, without symptoms of Zika, who have possible Zika virus exposure and
- have concerning ultrasound findings or who deliver an infant with concerning findings related to
congenital Zika syndrome or
- have ongoing possible Zika virus exposure (at least monthly travel to a Zika-affected area, or unprotected sex with a partner who frequently travels to a Zika-affected area).
- Infants whose mothers have possible Zika virus exposure and
- are born with birth defects consistent with
congenital Zika syndrome or
- have maternal laboratory evidence of possible Zika virus infection during pregnancy.
NOTE: Zika virus testing is no longer routinely recommended for asymptomatic pregnant women with recent possible Zika virus exposure, but without ongoing exposure.
Testing asymptomatic individuals when there is a smaller number of new cases occurring could increase the likelihood of false-positive test results. Testing is not routinely recommended for asymptomatic pregnant women with some, but not ongoing, exposure; however, testing may be considered based on patient preferences and clinical judgement. Healthcare providers should discuss with their patients the limitations of testing and provide prevention guidance, including avoiding unprotected sex for the duration of the pregnancy.
For more detailed information, please see the
CDC Testing Guidance and the Oregon Zika Investigative Guidelines (pdf).
CDC recommends that dengue and chikungunya testing should also be done for those who meet Zika testing criteria as a suspect case. Dengue and chikungunya serologies are not currently available at OSPHL and can be done through commercial labs. Please see
CDC laboratory guidance.
Fact SSheets for Patients: What You Should Know About Zika Virus Testing
Limitations of Testing
Zika IgM antibodies can persist for months to years following infection and detection may not be indicative of a recent infection. Plaque reduction neutralization testing (PRNT) is needed to confirm Zika virus infection after a positive IgM test; however, PRNT results do not always yield a specific flavivirus result.
Read more about
understanding Zika virus test results.
Guidance for pregnant women
Guidance for couples considering pregnancy and women who could become pregnant
- CDC recommends precautions for women and their partners thinking about pregnancy. Couples should consider avoiding nonessential travel to areas with Zika. CDC suggests the timeframes outlined below for couples to wait before trying to get pregnant.
Suggested timeframe to wait before trying to get pregnant
|Possible Zika exposure via recent travel or
sex without a condom with a partner infected with Zika
- Wait at least 8 weeks after symptoms start or last possible exposure
- Wait at least 3 months after symptoms start or last possible exposure
Read more here:
CDC guidance for women trying to become pregnant
Guidance for travelers
- Travelers to Zika-affected areas should actively
avoid mosquito bites and unprotected
sexual contact with others in the affected area. These precautions are recommended for all people who travel to Zika-affected areas.
- Returning travelers should
avoid mosquito bites for three weeks after their last exposure. The goal is to minimize risk of introduction of the virus into local mosquito populations.
- Travelers who have pregnant partners should
avoid sex or use a condom or other barrier methods during any sexual activity (vaginal, anal, oral, and sharing of sex toys) for the rest of the pregnancy.
- For more details, see
Protect yourself during sex on CDC's Zika website.
- Read more here:
CDC guidance to protect yourself and others
For prenatal providers
CDC guidance for clinical management of pregnant women with possible Zika virus exposure can be
For pregnant women with possible Zika virus exposure who were not tested or who were tested more than 12 weeks from their symptom onset or last exposure, placenta testing at the time of birth should be considered if ultrasound findings show evidence of congenital Zika syndrome (for example, microcephaly). Placenta testing can help to confirm maternal Zika infection. Testing is done at CDC and requires pre-approval for submission and testing.
For more detailed information, please see the CDC Testing Guidance and the
Oregon Zika Investigative Guidelines (pdf).
See also CDC's Update:
Interim Guidance for Prevention of Sexual Transmission of Zika Virus - United States, August 2018.
For pediatric providers
Zika virus can cause serious birth defects in infants whose mothers had Zika infection during pregnancy. A distinct pattern of birth defects has been recognized as
congenital Zika syndrome and includes:
- Intracranial calcifications
- Damage to the back of the eye
- Congenital contractures
It is possible that an infant born to a mother with possible Zika virus exposure may have congenital Zika infection. New findings suggest that infants with congenital Zika infection may appear healthy at birth but could have underlying brain abnormalities or other Zika-related health issues.
The links below provide additional information on the clinical evaluation and management of infants born to mothers with possible Zika virus exposure.
If you suspect an infant or fetus might have clinical findings compatible with congenital Zika infection, determine whether the mother has possible exposure to Zika. If so, along with PCR and IgM testing at a private laboratory, placenta testing at CDC may be recommended. Contact the
local health department in the mother’s county of residence to discuss recommendations for placenta testing.
Oregon resources for early intervention and family support services
For more information, please visit
CDC's Zika webpage for health care providers or call your
local health department (pdf) (call the "CD Nurse" Communicable Disease number). Clinicians needing communications materials to assist with raising awareness about Zika among their patients, prevention, or counseling for patients with positive test results can visit
CDC’s Zika Communication Toolkits and click on the "Healthcare Providers and Management" tab. Alternate language formats