Recommendations for assessment of pregnant women with potential exposure to Zika virus

Zika virus in a pregnant woman can be transmitted to the fetus, and can cause certain congenital abnormalities (including microcephaly). A small number of studies are available on the frequency of congenital defects in babies exposed to Zika in-utero, refer to the section Zika virus infection in pregnancy in the Information for clinicians.

The following recommendations for testing and follow up are being made in order to manage any risk. These recommendations will be updated as more information becomes available about the extent of the risk.

All pregnant women

Healthcare providers should ask about potential exposures to Zika virus.

Potential exposures include:

• Travel to a Zika affected country or country potentially affected by Zika (refer to the United States Centers for Diseases Control and Prevention (CDC) Zika Travel Information page for country-specific information).
• Unprotected sex (oral/anal/vaginal) with an individual with confirmed Zika virus infection.
• Unprotected sex (oral/anal/vaginal) with a traveller who has returned from a Zika affected country or a country potentially affected by Zika.

Pregnant women with potential exposure to the Zika virus

• Laboratory testing should be considered for pregnant women with a potential exposure to Zika virus during or immediately prior to pregnancy.
• The available tests for Zika virus may require 4 weeks following the last potential exposure to give a result. For some, the results will not provide complete reassurance that they have not had a Zika virus infection.
• There is no specific treatment for Zika virus if a positive test is returned.
• A positive test in the mother gives no information on whether the fetus is infected or harmed.
• Refer to Table 1 for detailed information on timing of tests, specimen collection, and recommended follow-up based on results.

To assist in interpretation of results, specimens should be collected at the time of the initial consultation for all pregnant women who have potentially been exposed to Zika virus.

Symptomatic pregnant women

• Testing should be offered to symptomatic pregnant women with a potential exposure to Zika virus. A complete check for travel related illnesses compatible with symptoms of Zika virus infection is advised in addition to testing for Zika virus.
• Symptoms compatible with Zika virus infection may include a low-grade fever, arthralgia (notably of small joints of hands and feet, with possible swollen joints), myalgia, headache, retro-ocular headaches, conjunctivitis, cutaneous maculopapular rash, and post-infection asthenia. These overlap with other arboviral illnesses such as dengue and chikungunya, although Zika virus infection usually has a milder clinical course. Malaria may be another potential differential diagnosis in returned travellers from certain regions.
• In a symptomatic pregnant woman, it is recommended to seek specialist infectious disease advice to discuss the possible range of differential diagnoses.
• Refer to Table 1 for detailed information on timing of tests, specimen collection, and recommended follow-up based on results.

Asymptomatic pregnant women

• Testing of asymptomatic pregnant women with a history of potential exposure to Zika virus can be more difficult to interpret.
• A detailed history should be taken to assess the risk of exposure, which would include the dates and duration of travel to Zika affected or potentially Zika affected countries, exposure to mosquito bites, and details of relevant sexual exposures while travelling or with people who have travelled to Zika virus affected countries.
• There is a low chance of the disease being present in most returned travellers.
• Testing risks false positive results and this needs to be discussed with the pregnant woman.
• Refer to Table 1 for detailed information on timing of tests, specimen collection, and recommended follow-up based on results.

For asymptomatic women who present less than 2 weeks following their last potential exposure, baseline samples collected at the time of consultation should be held at the laboratory for later reference if required.

For guidance on obstetric management including ultrasound surveillance please refer to the RANZCOG guideline.

Table 1.

Notes:

• MFM = maternal fetal medicine unit.
• Specialist obstetric advice and management - refer to RANZCOG guideline.
• ^#Repeat serum samples should be collected at least 2 weeks after the previous sample and at least 4 weeks after the last possible exposure to allow for antibody development and a rising titre to be detected.
• ^{^}Symptoms compatible with Zika virus infection may include a low-grade fever arthralgia (notably of small joints of hands and feet, with possible swollen joints), myalgia, headache, retro-ocular headaches, conjunctivitis, cutaneous maculopapular rash, post-infection asthenia which seems to be frequent.
• ^*Where jurisdictions have capacity, additional testing may be performed
• If an alternative diagnosis is confirmed this should be managed as appropriate.

No Zika virus assays, PCR or serology, are currently validated to guide management of pregnant women, and results must be interpreted cautiously together with all available clinical & laboratory data.

Figure 1 - Pregnant woman with potential exposure to Zika while pregnant or in the periconceptual⁺ period

⁺One month prior to the approximate time of conception.

^*Possible further investigations include repeat serology, serial ultrasounds, and amniocentesis

^{^}Referral for obstetric evaluation and further testing if any abnormalities on ultrasound.

Samples from asymptomatic pregnant women with recent exposure to Zika virus will be held until the second serological sample is tested. At that time, further testing on the acute sample will be performed if required.

When ordering testing for Zika virus, please order:

• Relevant Zika virus testing according to the guidelines
• Additional testing as required. (e.g. dengue, chikungunya and other relevant infections, FBC).

Additional information to assist the pathologist may include:

• Country or countries visited
• Dates of travel (arrival and departure in each country)
• Relevant symptoms and date of onset/cessation
• History (including approximate dates) of receiving any flavivirus vaccine ( e.g. Japanese encephalitis, yellow fever) or previous flavivirus illness (e.g. West Nile virus, dengue)
• Pregnancy status – yes, no, unknown
• If testing follows abnormal ultrasound , describe findings (normal, microcephaly suspected, CNS calcification)
• Other information that you believe may help the pathologist.