Zika Virus: Common Questions and Answers
Am Fam Physician. 2017 Apr 15;95(8):507-513.
Author disclosure: No relevant financial affiliations.
Since local mosquito-borne transmission of Zika virus was first reported in Brazil in early 2015, the virus has spread rapidly, with active transmission reported in at least 61 countries and territories worldwide, including the United States. Zika virus infection during pregnancy is a cause of microcephaly and other severe brain anomalies. The virus is transmitted primarily through the bite of an infected Aedes mosquito, but other routes of transmission include sexual, mother-to-fetus during pregnancy, mother-to-infant at delivery, laboratory exposure, and, possibly, transfusion of blood products. Most persons with Zika virus infection are asymptomatic or have only mild symptoms; hospitalizations and deaths are rare. When symptoms are present, maculopapular rash, fever, arthralgia, and conjunctivitis are most common. Zika virus testing is recommended for persons with possible exposure (those who have traveled to or live in an area with active transmission, or persons who had sex without a condom with a person with possible exposure) if they have symptoms consistent with Zika virus disease. Testing is also recommended for pregnant women with possible exposure, regardless of whether symptoms are present. Treatment is supportive, and no vaccine is currently available. The primary methods of prevention include avoiding bites of infected Aedes mosquitoes and reducing the risk of sexual transmission. Pregnant women should not travel to areas with active Zika virus transmission, and men and women who are planning to conceive in the near future should consider avoiding nonessential travel to these areas. Condoms can reduce the risk of sexual transmission.
Zika virus is a single-stranded RNA flavivirus closely related to dengue, yellow fever, and West Nile viruses, and it is most commonly transmitted through the bite of infected Aedes (Stegomyia) mosquitoes.1 Zika virus was first isolated in Uganda in 1947, but has only been recognized to cause large outbreaks of human disease since 2007.2,3 Several months after a 2015 outbreak of Zika virus in Brazil,4 reports of microcephaly in newborns increased.5 A subsequent evidence review using a systematic framework concluded that prenatal Zika virus infection causes microcephaly and other serious brain anomalies.6 Further epidemiologic and experimental evidence that Zika virus causes birth defects has accumulated.7–9
SORT: KEY RECOMMENDATIONS FOR PRACTICE
|Clinical recommendation||Evidence rating||References|
For pregnant women (symptomatic* and asymptomatic) who are evaluated two to 12 weeks after possible exposure to Zika virus,† serum IgM testing is recommended. If results are positive or equivocal, serum and urine RNA NAT should be performed. If RNA NAT results are negative, PRNT should be performed.
Asymptomatic pregnant women who live in areas with active Zika virus transmission should have Zika virus IgM testing as part of routine obstetric care during the first and second trimesters, with immediate RNA NAT for those with positive IgM results.
For symptomatic* persons (including pregnant women) with possible exposure to Zika virus† who present less than two weeks after symptom onset, serum and urine RNA NAT is recommended. If results are negative, serum IgM testing should be performed, and a positive or equivocal IgM result should be confirmed by PRNT.
For asymptomatic pregnant women with possible exposure to Zika virus† who do not live in areas with active Zika virus transmission, serum and urine RNA NAT is recommended if the samples are collected less than two weeks after the last possible exposure. If results are negative, Zika virus IgM testing should be performed on serum collected two to 12 weeks after possible exposure, and a positive or equivocal IgM result should be confirmed by PRNT.
For symptomatic* persons with possible exposure to Zika virus† who present two weeks or more after symptom onset, serum IgM testing should be performed. In nonpregnant women, a positive or equivocal IgM result should be followed by PRNT to confirm the diagnosis.
Pregnant women should not travel to areas with active Zika virus transmission.
Men and women who do not live in areas with active Zika virus transmission and who are planning to conceive in the near future should consider avoiding nonessential travel to areas with active Zika virus transmission.
All persons who live in or travel to an area with active Zika virus transmission should be counseled on strategies to prevent transmission of Zika virus and other mosquito-borne diseases. This includes using Environmental Protection Agency–registered insect repellents, wearing long-sleeved shirts and long pants, using permethrin-treated clothing (except in Puerto Rico), and using air conditioning or window and door screens when indoors.
Pregnant women with partners who live in or have traveled to an area with active Zika virus transmission should use condoms every time they have sex or should
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