Zika virus infection in a pregnant woman can cause microcephaly and other congenital brain abnormalities in the fetus. CDC recommends that pregnant women not travel to any area with ongoing local transmission of Zika virus. Pregnant women who travel to these areas should talk to their health care provider first and strictly follow steps to prevent mosquito bites. Women who are trying to become pregnant should consult with their health care provider before traveling to an area with ongoing local transmission and strictly follow steps to avoid mosquito bites during the trip.
Pregnant women who live in or have a history of travel to an area where Zika virus transmission is ongoing should be tested for Zika virus infection if they: 1) report ≥1 symptom consistent with Zika virus disease during or within 2 weeks of travel or 2) have ultrasound findings of fetal microcephaly or intracranial calcifications. Laboratory testing can be offered within 2-12 weeks of travel to pregnant women without clinical illness consistent with Zika virus disease, and should be offered to pregnant women who live in an areas with Zika upon initiation of prenatal care, and if the initial test is negative, in the mid-second trimester. Fetuses and infants of women infected with Zika virus during pregnancy should be evaluated for possible congenital infection.
Men who have traveled to an area with Zika and have a pregnant partner should use condoms or not have sex (vaginal, anal, or oral) during the pregnancy.
Men and their female partners who have returned from areas with active Zika virus transmission should consider preconception counseling with their health care provider and wait to attempt conception until the risk for sexual transmission is believed to be minimal. Women with Zika virus disease or possible exposure should wait at least 8 weeks after symptom onset or after last date of possible exposure before attempting conception. Men who have had a diagnosis of Zika virus disease should wait at least 6 months after symptom onset before attempting conception, Men who have had possible Zika virus exposure without clinical illness consistent with Zika virus disease should wait at least 8 weeks after last date of possible exposure before attempting conception. These recommendations may change as more data about Zika virus during the periconceptional period become available.
Healthcare providers can contact the CDC Zika Pregnancy hotline (available through the EOC Watch Desk at 770-488-7100, ZikaMCH@cdc.gov or ZikaPregnancy@cdc.gov or fax 404-718-2200) for clinical consultation on Zika virus infection in pregnancy.
Zika virus is a single-stranded RNA virus of the Flaviviridae family, genus Flavivirus.
Transmission occurs through the bite of an infected Aedes species mosquito. Intrauterine, perinatal, sexual, laboratory, and possible transfusion-associated transmission also have been reported. Although Zika viral particles were found in the breast milk of one woman and virus RNA has been detected in breast milk of two additional women, transmission of Zika virus through breastfeeding has not been documented.
Zika virus was first identified in Uganda in 1947. Prior to 2007, only sporadic human disease cases were reported from countries in Africa and Asia. In 2007, the first documented Zika virus disease outbreak was reported in the Federated States of Micronesia. In subsequent years, outbreaks of Zika virus disease were identified in countries in Southeast Asia and the Western Pacific. In 2015, Zika virus was identified for the first time in the Western hemisphere with large outbreaks reported in Brazil. Since then, the virus spread throughout much of the Americas. (See Zika Travel Information for a list of countries with current CDC travel notices for Zika virus.)
Most Zika virus infections are asymptomatic. Symptomatic infections are generally mild. Commonly reported signs and symptoms include fever, maculopapular rash, arthralgia, and conjunctivitis. Other symptoms include myalgia, headache, and vomiting. During the outbreak in Brazil in 2015, the Ministry of Health of Brazil reported a marked increase in the number of infants born with microcephaly, although it is not known how many of these cases were associated with Zika virus infection. Zika virus RNA was subsequently identified in tissues from several infants with microcephaly and from fetal losses in women who were infected during pregnancy. Guillain-Barré syndrome also has been reported in some patients after Zika virus infection.
Zika virus infection should be considered in patients with acute onset of fever, maculopapular rash, arthralgia, or conjunctivitis who live in or have traveled to an area with ongoing transmission in the 2 weeks preceding illness onset. Because dengue and chikungunya virus infections share a similar geographic distribution and symptomology with Zika, patients with suspected Zika virus infection should also be evaluated and managed for possible dengue or chikungunya virus infection. Other considerations in the differential diagnosis include malaria, rubella, measles, parvovirus, adenovirus, enterovirus, leptospirosis, rickettsiosis, and group A streptococcal infections.
For persons with suspected Zika virus disease, Zika virus rRT-PCR should be performed on urine specimens collected <14 days after onset of symptoms and serum specimens collected <7 days after onset of symptoms. A positive rRT-PCR result confirms Zika virus infection, and no antibody testing is indicated. Serum IgM antibody testing should be performed if rRT-PCR is negative or for samples collected ≥7 days after illness onset. However, these serologic assays can be positive because of cross-reacting antibodies against related flaviviruses (such as dengue or yellow fever viruses). Virus-specific neutralization testing can be used to discriminate between cross-reacting antibodies in primary flavivirus infections, although neutralizing antibodies might still yield cross-reactive results in people who were previously infected or vaccinated against a related flavivirus (secondary flavivirus infection).
Health care providers are encouraged to report suspected Zika virus disease cases to their state or local health departments to facilitate diagnosis and mitigate the risk for local transmission in areas where Aedes species mosquitoes are active. Zika virus disease is a nationally notifiable condition. State health departments should report laboratory-confirmed cases to CDC according to the Council of States and Territorial Epidemiologists (CSTE) case definitions. Pregnant women with laboratory evidence of Zika virus infection should be reported to the U.S. Zika Pregnancy Registry or the Puerto Rico Zika Active Pregnancy Surveillance System for clinical follow-up.
No specific antiviral treatment is available for Zika virus disease. Treatment is generally supportive and can include rest, fluids, and use of analgesics and antipyretics. Aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) should be avoided until dengue can be ruled out to reduce the risk of hemorrhage. People infected with Zika, dengue, or chikungunya virus should be protected from further mosquito exposure during the first week of illness to reduce the risk of local transmission. Pregnant women with laboratory evidence of Zika virus infection should be evaluated and managed for possible adverse pregnancy outcomes.
Avoiding mosquito bites can protect against Zika virus infection (see Chapter 2, Protection against Mosquitoes, Ticks, & Other Arthropods). Using condoms during sexual contact with people with possible Zika virus infection also may reduce transmission risk. For more information on sexual transmission of Zika, see Guidance for Prevention of Sexual Transmission of Zika Virus. Zika virus likely can be spread through blood transfusions. Blood donors returning from areas with active transmission of Zika virus should defer donation for 4 weeks after return (or 4 weeks after resolution of symptoms, if they become ill with symptoms consistent with Zika virus). Mothers are encouraged to breastfeed infants even in areas where Zika virus is circulating, as available evidence indicates the benefits of breastfeeding outweigh any theoretical risks associated with Zika virus infection transmission through breast milk.
Petersen LR, Jamieson DJ, Powesr AM, Honein MA. Zika virus. N Engl J Med 2016;374:1552–63.
Besnard M, Lastere S, Teissier A, Cao-Lormeau V, Musso D. Evidence of perinatal transmission of Zika virus, French Polynesia, December 2013 and February 2014. Euro Surveill. 2014;19(13).
Duffy MR, Chen TH, Hancock WT, Powers AM, Kool JL, Lanciotti RS, et al. Zika virus outbreak on Yap Island, Federated States of Micronesia. N Engl J Med. 2009 Jun 11;360(24):2536–43.
Foy BD, Kobylinski KC, Chilson Foy JL, Blitvich BJ, Travassos da Rosa A, Haddow AD, et al. Probable non-vector-borne transmission of Zika virus, Colorado, USA. Emerg Infect Dis. 2011 May;17(5):880–2.
Staples JE, Dziuban EJ, Fischer M, Cragan JD, Rasmussen SA, Cannon MA, et al. Interim guidelines for the evaluation and testing of infants with possible congenital Zika virus infection ― United States, 2016. MMWR Morb Mortal Wkly Rep 2016;65: 63–67.
Petersen EE, Polen KN, Meaney-Delman D, Ellington SR, Oduyebo T, Cohn A, et al. Update: Interim guidance for health care providers caring for women of reproductive age with possible Zika virus exposure — United States 2016. MMWR Morb Mortal Wkly Rep 2016; 65: 315–322.