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Exposure, Testing & Risks

Possible exposure to Zika includes:

  • Living in or having recently traveled to an area with risk of Zika, or
  • Having sex (vaginal, anal, or oral or the sharing of sex toys) without a condom with someone who lives in or has recently traveled to an area with risk of Zika

Testing Recommendations for Non-Pregnant Women and Men

Zika virus testing is indicated for non-pregnant women and men who have possible exposure to Zika and who experience symptoms of Zika virus disease. Routine testing is not currently recommended for women who are not pregnant and men who have possible exposure to Zika virus but no clinical illness. No test is 100% accurate. The performance of the test in people without symptoms is unknown, and results might be difficult to interpret. A test result can sometimes be negative in the setting of true infection, and the results could be falsely reassuring. For example:

  • If the serum or blood PCR is performed after the virus is no longer in the blood, Zika could still be present in other bodily fluids (e.g., semen). In those situations, the blood test would be negative but the person could still be carrying the virus in other bodily fluids.
  • If the IgM test is performed too early after infection when the antibody levels are not yet high enough, the results could be negative.
  • If the antibody test is performed after the IgM has waned, the results could be negative.

We currently have limited understanding of Zika virus shedding in genital secretions or of how to interpret the results of tests of semen or vaginal fluids. Zika shedding in these secretions may be intermittent, in which case a person could test negative at one point but still carry the virus and shed it again in the future.

Note: CDC issued a Health Alert Notice (HAN) to share emerging evidence about interpreting Zika IgM antibody test results of women who may have been exposed to Zika virus, particularly women who live in or frequently travel to areas with a CDC Zika travel notice. For women planning to become pregnant who might have been exposed to Zika previously, healthcare providers can consider testing for Zika antibody before pregnancy. Antibody test results before pregnancy should not be used to determine if it is safe for a woman to become pregnant. Rather, testing before pregnancy can help determine whether a woman becomes infected during pregnancy. CDC is currently updating its webpages with this information.

Risks

Because Zika virus infection is a cause of microcephaly and other severe fetal brain defects, pregnancy planning in the context of the Zika outbreak is important. There is limited information available about the risk for adverse pregnancy outcomes around periconceptional Zika virus infection (defined as infection during 8 weeks before conception or 6 weeks before last menstrual period). To date, there have been no published reports of adverse pregnancy outcomes after periconceptional Zika virus infection. Infections with other viruses (e.g., cytomegalovirus, rubella, parvovirus) around the time of conception have been associated with congenital infection and adverse pregnancy outcomes, although the exact timing of infection relative to conception was sometimes uncertain.

Future Pregnancy

There is no evidence that prior Zika virus infection poses a risk of birth defects in future pregnancies. There is no evidence that a fetus conceived after the virus has cleared the woman’s body would be at risk for fetal Zika infection.

Fertility Treatment

No instances of Zika virus transmission during fertility treatment have been documented, but transmission through donated gametes or embryos is theoretically possible. Zika virus has been detected in semen, and sexual transmission has occurred. The US Food and Drug Administration has issued guidance[PDF - 10 pages] providing recommendations to reduce the potential transmission risk of Zika virus through donated tissues, including donated sperm, oocytes, and embryos from anonymous donors.

Fertility treatment for sexually intimate couples using their own gametes and embryos should follow the testing and timing recommendations for couples attempting conception, although recommendations might need to be adjusted depending on individual circumstances.

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