Zika virus: Sexual contact risk may be limited to short window

This study illustrates the apparent shortcomings of current virus-detection standards in terms of their relevance to public health, according to Heinz Feldmann, MD.

Approximately 4% of Zika virus RNA-positive semen samples were infectious, according to the report, and of those infectious samples, all were obtained within 30 days of the onset of illness. “This finding suggests that there is a short period during which Zika virus–infected men might transmit this virus through sexual contact,” Dr. Feldmann wrote in an editorial.

Current practice in some areas is to test semen samples sequentially until two or more consecutive negative results are obtained; however, that approach is controversial, according to Dr. Feldmann, because the person could be shedding the virus intermittently because of the potential for virus latency and reactivation.

“This also raises the question of whether modern molecular approaches are properly positioned to detect virus latency rather than persistence,” he said in his editorial. The goal, he added, should be to determine infectivity, which is probably best assessed by means of viral isolation – which is believed to be less sensitive than molecular detection.

“Thus, the diagnostic situation is far more complicated than it seems,” he noted.

However, he added, these diagnostic scenarios may be less applicable for public health entities, which have “quickly” disseminated recommendations for safer sex to prevent Zika virus spread and the potentially devastating consequences of fetal infection.

“These recommendations leverage the best data available and have been implemented, but ought to be updated as new data emerge,” Dr. Feldmann wrote.

Dr. Feldmann is with the National Institute of Allergy and Infectious Diseases, National Institutes of Health, and Rocky Mountain Laboratories, Hamilton, Mont. These comments are derived from his editorial N Engl J Med 2018;378:1377-85 . Dr. Feldmann reported that he had nothing to disclose related to the editorial.