Zika virus is a flavivirus closely related to dengue, West Nile, and yellow fever viruses. Although spread is primarily by Aedes species mosquitoes, two instances of sexual transmission of Zika virus have been reported (1,2), and replicative virus has been isolated from semen of one man with hematospermia (3). On February 5, 2016, CDC published recommendations for preventing sexual transmission of Zika virus (4). Updated prevention guidelines were published on February 23.* During February 6–22, 2016, CDC received reports of 14 instances of suspected sexual transmission of Zika virus. Among these, two laboratory-confirmed cases and four probable cases of Zika virus disease have been identified among women whose only known risk factor was sexual contact with a symptomatic male partner with recent travel to an area with ongoing Zika virus transmission. Two instances have been excluded based on additional information, and six others are still under investigation. State, territorial, and local public health departments, clinicians, and the public should be aware of current recommendations for preventing sexual transmission of Zika virus, particularly to pregnant women (4). Men who reside in or have traveled to an area of ongoing Zika virus transmission and have a pregnant partner should abstain from sexual activity or consistently and correctly use condoms during sex with their pregnant partner for the duration of the pregnancy (4).

Zika virus disease is an arboviral disease and a nationally notifiable condition in the United States (5). For the purposes of this report, a confirmed or probable case of sexually transmitted Zika virus disease was defined as an illness meeting the confirmed or probable arbovirus surveillance case definition in a person whose only known risk factor was sexual contact with a partner who recently traveled to an area with ongoing Zika virus transmission (6).

During February 6–22, 2016, two confirmed and four probable cases of Zika virus sexual transmission were reported to CDC by health officials from multiple states. Median patient age was 22.5 years (range = 19–55 years), and several women were pregnant. In all cases where type of sexual contact was documented, the contact included condomless vaginal intercourse and occurred when the male partner was symptomatic or shortly after symptoms resolved. Three illustrative cases are presented.

Case 1. In mid-January, immediately after returning to the United States from a 10-day trip to the Caribbean, a man developed illness with fever, arthralgia, bilateral conjunctivitis, and a maculopapular, pruritic rash. The illness lasted 6 days. No hematospermia or prostatitis was noted. On the 1st or 2nd second day of illness, he had condomless vaginal intercourse with his female partner. The woman developed a febrile illness 13–14 days after sexual contact, with rash, conjunctivitis, and myalgia. Zika virus RNA was detected in the woman’s serum by reverse transcription-polymerase chain reaction (RT-PCR) assay. Test results for the man are pending. The woman had no recent history of travel outside of the continental United States, and local mosquito-borne transmission of Zika virus was not considered possible; the vectors that transmit the virus are not present or active where she lives, based on the location and current temperatures.

Case 2. In late January, a man returned to the United States after a 4-week trip to Central America. The same day, he developed fever, arthralgia, generalized pruritus, myalgia, and eye discomfort. He had condomless vaginal intercourse with his female partner several times during the following 8 days. Ten days after the man’s return, his female partner developed fever, pruritic rash, arthralgia, eye pain, photophobia, headache, vomiting, and myalgia. Zika virus infection in the woman was confirmed by RT-PCR testing of serum. Serum collected from the man tested positive for Zika virus immunoglobulin M (IgM) antibodies; confirmation is pending. The woman had no recent history of travel outside the continental United States, and current local mosquito-borne transmission of Zika virus was not considered possible where she lives.

Case 3. In mid-January, a man returned from Central America with fever, rash, arthralgia, conjunctivitis, headache, and myalgia. His symptoms began 3 days earlier and persisted until approximately 3 days after his return. On the day of his return, he had sexual contact with his female partner. Ten days later, the woman developed rash, arthralgia, conjunctivitis, and myalgia. Serum collected from the woman tested positive for Zika virus IgM; confirmation is pending. Test results for the man are pending. The woman had no recent history of travel outside of the continental United States, and current local mosquito-borne transmission of Zika virus was not considered possible where she lives.

References

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After reports of microcephaly and other adverse pregnancy outcomes in infants of mothers infected with Zika virus during pregnancy, CDC issued a travel alert on January 15, 2016, advising pregnant women to consider postponing travel to areas with active transmission of Zika virus. On January 19, CDC released interim guidelines for U.S. health care providers caring for pregnant women with travel to an affected area (1), and an update was released on February 5 (2). As of February 17, CDC had received reports of nine pregnant travelers with laboratory-confirmed Zika virus disease; 10 additional reports of Zika virus disease among pregnant women are currently under investigation. No Zika virus–related hospitalizations or deaths among pregnant women were reported. Pregnancy outcomes among the nine confirmed cases included two early pregnancy losses, two elective terminations, and three live births (two apparently healthy infants and one infant with severe microcephaly); two pregnancies (approximately 18 weeks’ and 34 weeks’ gestation) are continuing without known complications. Confirmed cases of Zika virus infection were reported among women who had traveled to one or more of the following nine areas with ongoing local transmission of Zika virus: American Samoa, Brazil, El Salvador, Guatemala, Haiti, Honduras, Mexico, Puerto Rico, and Samoa. This report summarizes findings from the nine women with confirmed Zika virus infection during pregnancy, including case reports for four women with various clinical outcomes. U.S. health care providers caring for pregnant women with possible Zika virus exposure during pregnancy should follow CDC guidelines for patient evaluation and management (1,2). Zika virus disease is a nationally notifiable condition. CDC has developed a voluntary registry to collect information about U.S. pregnant women with confirmed Zika virus infection and their infants. Information about the registry is in preparation and will be available on the CDC website.

Zika virus is a mosquito-borne flavivirus that was first isolated from a rhesus monkey in Uganda in 1947 (3). For several decades, only sporadic human disease cases were reported from Africa and Southeast Asia. In 2007, an outbreak was reported on Yap Island, Federated States of Micronesia (3), and outbreaks subsequently were reported from several Pacific Island countries (4). Local transmission of Zika virus was first identified in the Region of the Americas (Americas) in Brazil in May 2015 (5). Since that time, transmission of Zika virus has occurred throughout much of the Americas; as of February 18, a total of 32 countries and territories worldwide have active transmission of Zika virus (http://www.cdc.gov/zika/geo/active-countries.html). Interim guidelines for evaluation and management of pregnant women who have traveled to areas with ongoing local transmission of Zika virus include offering laboratory testing after return from travel (2).

During August 1, 2015–February 10, 2016, CDC received 257 requests for Zika virus testing for pregnant women. Among these requests, 151 (59%) included information indicating that the woman had a clinical illness consistent with Zika virus disease (i.e., two or more of the following signs or symptoms: acute onset of fever, rash, conjunctivitis, or arthralgia). The remaining requests did not document an illness compatible with Zika virus disease, but reporting of symptom information might have been incomplete.

Laboratory confirmation of recent Zika virus infection includes detection of 1) Zika virus, viral RNA, or viral antigen, or 2) Zika virus immunoglobulin M (IgM) antibodies with Zika virus neutralizing antibody titers ≥4-fold higher than neutralizing antibody titers against dengue or other flaviviruses endemic to the region where exposure occurred. Among the 257 pregnant women whose specimens were tested at CDC, 249 (97%) tested negative for recent Zika virus infection and eight (3%) had confirmed Zika virus infection. In addition to the eight patients with laboratory testing performed at CDC, one confirmed case was reported to CDC from a state health department with capacity to test for Zika virus infection.

Among nine pregnant women with confirmed Zika virus disease, no hospitalizations or deaths were reported. All nine women reported at least one of the four most commonly observed symptoms (fever, rash, conjunctivitis, or arthralgia), all women reported rash, and all but one woman had at least two symptoms. Among the six pregnant women with Zika virus disease who reported symptoms during the first trimester, outcomes included two early pregnancy losses, two elective pregnancy terminations, and delivery of a live born infant with microcephaly; one pregnancy is continuing. Among two women with Zika virus infection who had symptoms during the second trimester of pregnancy, one apparently healthy infant has been born and one pregnancy is continuing. One pregnant woman reported symptoms of Zika virus infection in the third trimester of pregnancy, and she delivered a healthy infant.

References

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