More Attention Needed to Prevent Sexual Transmission of Zika.
While mosquitos have been the primary focus of controlling outbreaks of the Zika virus worldwide, there has been increased recognition of the importance of sexual transmission.
Now, a paper led by a School of Public Health researcher recommends that more efforts be made to reduce the risk of such transmission, including consistent international guidelines for travelers and their sexual partners, and more research into how the virus is secreted and passed on.
Writing in Current Infectious Disease Reports, David Hamer, professor of global health and of medicine at the School of Medicine, and colleagues note that there have been a number of cases of male-to-female sexual transmission through unprotected vaginal sex with both symptomatic and asymptomatic male partners. Studies that have examined the duration of semen carriage have detected the Zika virus for as long as 188 days after symptom onset.
“Given evidence of virus shedding in the female and male genital tract, and highly suggestive epidemiological evidence of transmission through unprotected sexual contact, there appears to be a definite risk of asymptomatic and symptomatic travelers transmitting Zika virus to their partners after travel to endemic areas,” Hamer and co-authors wrote.
They said developing “appropriate messages” for travelers and their sexual partners about how to prevent Zika infection has proven to be a challenge. While most health authorities advise that both symptomatic and asymptomatic men and women wait at least six months after returning from areas with the active virus before attempting conception, international and national recommendations regarding minimizing risks vary, they said.
The authors noted that numerous scientists are scrambling to find agents that can prevent Zika infection or slow its progress, and that some of those studies appear promising. Early findings provide evidence to support continued work using animal models “and perhaps limited clinical trials of drugs that have already undergone regulatory approval,” they said.
“An important issue for drugs used for treatment is whether they could reach protected sites, such as the central nervous system, fetus in utero, tissues of the eye, and the testes,” they said.
Zika virus is spread to people primarily through the bite of an infected mosquito (Aedes aegypti and Aedes albopictus). The illness is usually mild with symptoms lasting up to a week, and many people do not have symptoms or will have only mild symptoms. However, Zika virus infection during pregnancy can cause a serious birth defect called microcephaly and other severe brain defects.
The Centers for Disease Control and Prevention says the best way to prevent Zika is to protect against mosquito bites. The agency has advised pregnant women not to travel to areas where the virus is active.
Co-authors with Hamer were: Mary Wilson of the University of California–San Francisco and Harvard T.H. Chan School of Public Health; Lin Chen of Harvard Medical School and the Travel Medicine Center of Mount Auburn Hospital; and Jenny Jean, a student at the School of Medicine.
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