CDC warns against sexual transmission of Zika virus




In updated guidance, the U.S. Centers for Disease Control and Prevention advised pregnant women to use condoms or abstain from sex with men who have traveled to Zika-infected areas. The CDC also expanded Zika testing recommendations to advise testing all pregnant women who have traveled to Zika-infected areas, regardless of whether they have symptoms of Zika virus infection.

The CDC also now recommends that pregnant women postpone travel to Zika-infected areas.

Dr. Tom Frieden © CDC

Dr. Tom Frieden

Precautions to avoid potential sexual transmission of Zika virus follow a report earlier this week of sexual transmission of Zika virus from an individual who had traveled to a Zika-infected area, to that person’s sexual partner, who had not traveled to a Zika-infected area. The recommendation to consistently and correctly use condoms, or to abstain from sex, includes oral, anal, and vaginal insertive sex (MMWR Morb Mortal Wkly Rep. 2016 Feb 5;65[5]:1-2).

In a telebriefing, CDC director Dr. Tom Frieden said, “Because this phenomenon is so new, we are quite literally discovering more about it every day.”

The mosquito-borne flavivirus may be associated with an increased risk of microcephaly and other intracranial and neurologic abnormalities in infants whose mothers were infected with Zika virus during pregnancy. A possible link to Guillain-Barré syndrome is also being explored.

Zika virus infection is asymptomatic in 80% of individuals. Symptoms of infection, if they appear, include initial fever, a maculopapular rash, arthralgia, and sometimes conjunctivitis. There is no treatment for the disease and care is supportive.

Women who have traveled to an area with active Zika virus transmission but who have not shown symptoms of Zika virus should now be offered testing, if available, between 2 and 12 weeks from the travel date.

Testing for women who show symptoms consistent with Zika virus disease should include Zika virus reverse transcription polymerase chain reaction, Zika virus Immunoglobulin M (IgM), and neutralizing antibodies on serum specimens. Patients should also be evaluated for dengue and chikungunya virus infection because of the overlap in symptoms and endemic regions for the diseases. For those women who are pregnant and have traveled to a Zika-infected area, but who do not have symptoms of Zika infection, testing should include Zika virus IgM and, for positive or inconclusive IgM tests, neutralizing antibodies on serum specimens (MMWR Morb Mortal Wkly Rep. 2016 Feb 5;65[05]:1-6).

Dr. Frieden said that the CDC was working around the clock to make more test kits available, and is in active discussion with private manufacturers to expand production of test kits.

Brazilian researchers have issued a brief report that Zika virus has been found in urine and saliva, but Dr. Frieden clarified that today’s updated guidance does not address having women avoid exposure to urine or saliva of infected or potentially infected individuals. “We have no data on that, and we try to stick to the science here at the CDC,” he said, so current guidelines don’t address other modes of transmission, though study is ongoing. A focus of current study is to determine how long the virus persists in semen, though Dr. Frieden said it will take “weeks to months to come up with reliable information.”

Dr. Amesh A. Adalja, a member of the public health committee of the Infectious Disease Society of America and an instructor in the department of infectious diseases at the University of Pittsburgh Medical Center, said in an interview that new and emerging information about previously unknown Zika virus presentations “doesn’t change what we do know.” For most, he said, this is an asymptomatic to very mild, self-limiting disease. However, Dr. Adalja said, “We need to unravel the microcephaly link.” He called for case control studies to determine definitively if microcephaly is a “real signal” in Zika virus infection.

“It is important to step back and emphasize that Zika virus is overwhelmingly a mosquito-borne disease,” said Dr. Frieden. He said that the broader public health effort must focus on mosquito control. “The Aedes aegypti mosquito is an aggressive mosquito. It is ideally suited to the urban environment,” and the mosquito bites four or five people at one blood meal, and feeds throughout the day, not just at dawn and dusk, said Dr. Frieden. He emphasized that mosquito control measures are labor intensive and technically demanding. “This is not easy work,” he said.

Dr. Frieden said that the situation is rapidly evolving, and the CDC will continue sharing information as it becomes available. “Zika reminds us that nature is a formidable enemy,” he said.

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