Kinetics of Zika virus persistence in semen

Abstract

Objective Interim guidelines to prevent sexual transmission of Zika virus (ZIKV) do not recommend diagnostic testing, because the knowledge of viral kinetics in semen after acute infection is limited. We studied the presence and duration of ZIKV in semen after onset of symptoms. Methods A prospective observational cohort study (NCT 02733796) is ongoing to determine the presence, persistence and kinetics of ZIKV in semen of men with confirmed ZIKV infection after returning from areas with vector-borne transmission. ZIKV RT-PCR is performed in weekly semen samples until ZIKV is no longer detectable. The main endpoint is the proportion of ZIKV positive semen samples over time after acute ZIKV infection. We report preliminary findings after enrolment of the first 4 patients. Findings Semen of two out of four immunocompetent men with symptomatic ZIKV infection tested positive for ZIKV-RNA by RT-PCR. ZIKV levels in semen declined to undetectable after 68 and 56 days respectively, suggesting elimination of the virus. Conclusion Our findings indicate that presence and persistence of ZIKV in semen after acute infection appear common. Algorithms can be developed that incorporate ZIKV-specific molecular and antibody detection assays and subsequent testing for ZIKV in semen of selected men. We suggest that future guidelines to prevent sexual transmission of ZIKV, adopt diagnostic testing of both symptomatic and asymptomatic individuals returning from endemic areas.