Interim recommendations for assessment of pregnant women with potential exposure to Zika virus

The recommendations for Zika virus testing may change as the outbreak evolves. Please return to this website to check the latest recommendations before testing.

Page last updated: 19 August 2016

    Zika virus in a pregnant woman can be transmitted to the fetus, and can cause certain congenital abnormalities (including microcephaly). Further studies are required to understand the likelihood of adverse perinatal outcomes. While it is not possible at the current time to quantify the risk to the unborn baby of a person infected with Zika virus, 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 (refer to the list of Zika virus affected countries).
    • 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 virus affected country.

    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 and 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 virus 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.

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    Table 1.

    Time of exposure Clinical illness^ Acute specimens and testing to request Results of first test Repeat testing to be at least 2 weeks after first sample and at least 4 weeks following last potential exposure Results of second serological test Obstetric Follow-up
    Last potential exposure within the last 2 weeks Symptomatic PCR (blood and urine) and serology for suspected Zika virus

    Negative PCR for Zika virus#

    Negative serology

    Serology for suspected Zika virus infection

    Zika virus positive or indeterminate

    or indeterminate serology result repeat serology in 2 weeks

    Refer for obstetric specialist counselling and advice e.g. MFM if available
    Zika virus negative Provide routine pregnancy care
    Negative PCR for Zika virus#, Positive or indeterminate serology

    Further testing will be performed by the lab

    Repeat serology for suspected Zika virus infection

    Zika virus positive or indeterminate Refer for obstetric specialist counselling and advice e.g. MFM if available, after first serology test. Discuss results with pathologist. Review when further serology completed
    Zika virus negative Provide routine pregnancy care*

    Positive PCR#,

    Positive or Negative serology

    Serology for suspected Zika virus infection for confirmation Do not wait for serology results; refer on receipt of initial positive results. Refer for obstetric specialist counselling and advice e.g. MFM if available. Review when further serology completed.
    Asymptomatic PCR and serology for suspected Zika virus and stored for later analysis (acute phase samples) Not applicable – hold only*

    Serology for suspected Zika virus infection

    If positive, the laboratory will test the acute phase samples.

    Zika virus positive or indeterminate Discuss results with Pathologist and refer for obstetric specialist counselling and advice e.g. MFM if available
    Zika virus negative Provide routine pregnancy care
    Time of exposure Clinical illness^ Acute specimens and testing to request Results of first test Repeat testing to be at least 2 weeks after first sample and at least 4 weeks following last potential exposure Results of second serological test Obstetric Follow-up
    Last potential exposure more than 4 weeks ago Asymptomatic or symptomatic in past Serology for suspected Zika virus infection Zika virus negative Not required Provide routine pregnancy care
    Zika virus positive or indeterminate Consider repeating serology 2 weeks after the first sample Do not wait for second serology results; refer on receipt of first results. Refer for obstetric specialist counselling and advice e.g. MFM if available. Discuss with pathologist.
    Last potential exposure 2-4 weeks ago Asymptomatic or symptomatic in past

    Serology for suspected Zika virus infection

    PCR Urine

    Zika virus positive or indeterminate Consider repeating serology 2 weeks after the first sample Do not wait for second serology results; refer on receipt of first results. Refer for obstetric specialist counselling and advice e.g. MFM if available. Discuss results with pathologist.
    Zika virus negative Repeat serology for suspected Zika virus infection Zika virus positive or indeterminate Refer for obstetric specialist counselling and advice e.g. MFM if available. Discuss results with pathologist
    Zika virus negative Provide routine antenatal care.
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    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

    DThis chart provides an overview of the Interim recommendations for assessment of pregnant women returning from Zika virus-affected areas.

    #Repeat 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.

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

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

    +One month prior to the approximate time of conception.

    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.
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