A case report of a patient who apparently contracted Zika virus through anal sex may help provide insights on how to prevent further transmission of the virus, according to researchers writing in a recently published Morbidity and Mortality Weekly Report. 

John T Brooks, MD, from the Division of HIV/AIDS Prevention, National Center for HIV, Hepatitis, TB and STD Prevention at the CDC and colleagues note that the patient’s case was reported to the Dallas County Health and Human Services in Texas in January. The patient had returned to Texas after spending 1 week in Venezuela and had been with individuals exhibiting symptoms of Zika.

The day before and the day after patient A began showing symptoms of Zika himself, he engaged in anal sex without a condom with his long term, monogamous male partner of more than 10 years, who became patient B. Patient B, who had not traveled, showed symptoms 7 days after patient A. 


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The patients’ blood samples were tested for antibodies (IgM) and were positive. RT-PCR testing was negative. Serologic testing revealed the non-traveler had been exposed to Zika, which could only have happened through sex with his partner, Dr Brooks explained in an interview with Infectious Disease Advisor.

Investigators ruled out transmission by the Aedes aegypti and Ae. Albopictus mosquito, because the winter season is inhospitable to this vector’s activity in Texas. Researchers noted that Dallas will be in range for vector-borne Zika infection at other times of the year.

Previously published reports (5 cases) of sexual transmission of the Zika virus occurred only with male-to-female vaginal sex. Researchers reported that examination of infectious viral shedding of Zika in semen is ongoing, but that in this particular case, semen testing from the Dallas Health Department did not detect virus; the test was equivocal.

Dr Brooks said that, “The case in Dallas might have gone unrecognized were it not for a very astute clinician who considered the diagnosis. Clinicians should consider the possibility of sexually transmission of Zika virus in patients presenting with symptoms consistent with Zika virus illness but who neither live in nor have traveled recently to an area of active Zika virus transmission.”

He went on to advise practicing physicians during the interview that “Events such as the current Zika virus outbreak in Latin America illustrate the importance of routinely collecting a brief travel history and sex history from all patients.”

Reference

1. Deckard DT, Chung WM, Brooks JT, et al. Male-to-Male Sexual Transmission of Zika Virus — Texas, January 2016. MMWR 2016;65:372–374.