Key points about Zika virus
- Many countries including parts of the continental U.S. have been identified as areas with risk of Zika virus infections.Since 2016, the number of cases reported from Latin America and the Caribbean have fallen dramatically. However, transmission in these areas continues.
- 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 the Oregon State Public Health Lab and private laboratories.
- Advise patients to void mosquito bites and use condoms or abstain from sex following return from a Zika-affected area.
Zika Virus (Diseases A-Z) | Zika Virus Updates | Zika Information for Travelers
On this page:
Zika infection is reportable in Oregon. Healthcare providers are required to report suspect Zika virus infections to the local health department (pdf) in which the patient lives within one day (call the "CD Nurse" Communicable Disease number).
Whom to test
Use the algorithm below to help determine whether or not to test your patient for Zika.
For more detailed information, please see section 3 of the Oregon Zika Investigative Guidelines (pdf).
How to test
Both private labs and the Oregon State Public Health Laboratory (OSPHL) can test specimens for Zika.
- Specimens should be collected within 12 weeks of symptom onset or exposure. Any test run outside this range may not be sensitive enough to detect an infection.
- NOTE: If specimens from asymptomatic pregnant women are collected within 14 days of most recent exposure and serum and urine are negative by PCR, follow-up serum may be needed for additional testing.
Testing through OSPHL
If you are submitting your specimens to OSPHL, local health authorities must approve and coordinate testing of all initial and follow-up specimens. OSPHL can test for Zika virus via Trioplex PCR (which also detects dengue and chikungunya viruses) and Zika IgM.
Specimens submitted to OSPHL without prior approval will not be tested.
Testing through private labs
If you are pursuing Zika testing through a private commercial lab, consult your clinical laboratory for send-out options.
Currently, several commercial labs offer PCR and IgM testing for Zika virus. We recommend that providers follow CDC testing criteria for whom to test and guidance for what should be tested.
Updated guidance from CDC recommends that negative PCR tests for those meeting testing criteria as a suspect cased should be followed by IgM testing for Zika, dengue, and chikungunya virus infections. Dengue and chikungunya serologies are not currently available at OSPHL, and can be done through commercial labs. Please see CDC laboratory guidance.
Limitations of Testing
Testing for Zika virus infection is complex and has limitations. Both Zika PCR and IgM testing generally identify recent infection and may not be reliable more than 12 weeks after exposure. The Zika IgM test is not specific to Zika virus and a positive result may reflect cross-reactivity with other flaviviruses such as dengue. 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.
In addition, recent evidence has suggested that Zika antibodies may stay in the body for months after infection for some individuals. Therefore, Zika antibody testing for pregnant women may not be able to determine whether they were infected before or after they became pregnant.
Read more here about understanding Zika virus test results
Guidance for pregnant women
- CDC recommends that pregnant women do not travel to any area with a risk of Zika virus infection.
- If travel to a region with Zika virus risk is unavoidable, they should avoid mosquito bites and unprotected sexual contact with others in the affected area.
- Pregnant women should also avoid unprotected sex for the duration of the pregnancy with partners who have recently visited a Zika-affected area.
- For pregnant women who live in, or frequently travel (daily or weekly) to an area with a Zika travel notice, CDC recommends that health care providers can consider concurrent Zika virus NAT testing in addition to previously recommended IgM testing at least once per trimester to provide additional clinical information to determine whether a positive IgM test result indicates a recent infection.
- Read more here: CDC 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 6 months after symptoms start or last possible exposure
- For Oregon women planning to become pregnant who frequently travel (daily or weekly) to areas with a Zika travel notice, healthcare professionals can consider testing for Zika antibodies before pregnancy. Testing before pregnancy can guide test result interpretation in a subsequent pregnancy. However, antibody test results before pregnancy should not be used to determine if it is safe for a woman to become pregnant because the test results could have multiple interpretations and the test results represent a single point in time.
- For more detailed information, view CDC recommendations for women of reproductive age living in areas with Zika.
- 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.
For prenatal providers
CDC guidance for clinical management of pregnant women with possible Zika virus exposure can be found here.
See also CDC's Update: Interim Guidance for Prevention of Sexual Transmission of Zika Virus - United States, July 2016.
Webinar for midwives
The Oregon Health Authority conducted a Zika for Midwives webinar on November 10, 2016. The information provided was based on the available body of evidence at that time. When accessing the webinar, providers should keep in mind that our knowledge and guidance of Zika will change as more research is done. Providers should continue to update their knowledge of the disease and guidelines.
Watch the webinar: Zika for Midwives - November 10, 2016
For pediatric providers
It is possible that an infant with congenital Zika infection may be born to a mother with undetected illness. If you suspect an infant or fetus might have Zika infection, determine whether the mother has possible exposure to Zika. If so, contact the local health department (pdf) where the mother resides to arrange testing.
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 are available available here.