Sexual Transmission of the Zika Virus May Be Short

Zika virus is more likely transmitted from men to women, than from women to men

couple on beach

During the 2015-2017 Zika virus outbreak, many health authorities around the world reported a large number of travel-associated, sexual transmissions.

The first travel-related Zika case was identified when a scientist working in Senegal during 2008 developed Zika symptoms after returning to the USA.

And his wife, who had not traveled outside the USA since 2007, became sick 4 days later after having vaginal sexual intercourse in the days after the scientist returned home, but before the onset of his clinical illness.

To better understand Zika’s transmission routes, a new study performed a ‘living’, which is continually updated, systematic review of evidence published about sexual transmission of Zika and other arthropod-borne flaviviruses in humans.

The study included 48 publications describing 180 individuals who underwent diagnostic testing by RT-PCR or viral culture on semen, vaginal fluid, or saliva, at 1 or more time points.

This study’s conclusion so far, by Michel Counotte and Nicola Low of the University of Bern in Switzerland, and colleagues, suggests that the Zika virus is sexually transmissible in addition to its primary mosquito-borne route.

And, these findings suggest that the infectious period for sexual transmission of Zika is shorter than previous estimates.

These researchers reported Zika is more likely transmitted from men to women, than from women to men.

For sexual transmission of Zika, the median serial interval - the time between onset of symptoms in 2 sexual partners - was just 12 days.

And, the median duration of Zika RNA persistence in semen is longer (34 days) than in the female genital tract (12 days).

The Zika virus can be detected for longer periods of time using reverse transcription polymerase chain reaction, compared to viral culture.

These researchers said they will maintain the living systematic review and develop a study protocol that can be used to better monitor the sexual transmission of the Zika virus.

The views expressed in this article are those of the authors and do not necessarily represent the official positions of the World Health Organization, the University of Bern, the National Institute of Allergy and Infectious Diseases, or the Centers for Disease Control and Prevention.

Study funding: MJC and JW received salary support from Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung (CH) http://www.snf.ch/ Award Number: 320030_170069 & 320030_176233. MJC received salary support from World Health Organization contracts 2017/725385-0 and 2017/733494-0. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.