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 has 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 Laboratory and private laboratories.
- 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) | Zika Virus Updates | Zika Information for Travelers
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Zika infection is reportable in Oregon. Healthcare providers are required to report suspect Zika virus infections to the local health department (pdf) in the patient's county of residence 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.
NOTE: Zika virus testing is no longer routinely recommended for asymptomatic pregnant women with recent possible Zika virus exposure, but without ongoing exposure. This includes frequent (e.g., at least monthly) travel to a Zika-affected area, or unprotected sex with a partner who frequently travels to a Zika-affected area.
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 and should be pursued at private laboratories. 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 section 3 of the Oregon Zika Investigative Guidelines (pdf).
- Fact Sheets for Patients: What You Should Know About
Zika Virus Testing
- For Healthcare Providers: Pretest Counseling Conversation Guides
How to test
Both private labs and the Oregon State Public Health Laboratory (OSPHL) can test specimens for Zika.
- NOTE: Specimens should be collected within 12 weeks of symptom onset or exposure. Any test run outside this range may not reliably detect or rule outbe sensitive enough to detect an infection.
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 using a commercial lab for Zika testing, consult your lab 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.
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.
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. Zika IgM testing is not specific for 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 people. Therefore, Zika antibody testing for pregnant women may not distinguish between infections that developed before or after conception.
Read more here 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 6 months after symptoms start or last possible exposure
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
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.
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, contact the local health department (pdf) in the mother’s
county of residence. Appropriate testing can be arranged for the mother and/or the infant.
The links below provide additional information on the clinical evaluation and management of infants born to mothers with possible Zika virus exposure.
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 available here.