Sexual transmission of Zika virus: more to explore
Authors: Sachin Kumar
Journal: The Lancet Global Health (2018)

It was interesting to read the framework put forth by the WHO Zika Sexual Transmission Research Group and its further applicability (January, 2018).1Kim CR Counotte M Bernstein K et al.Investigating the sexual transmission of Zika virus.Lancet Glob Health. 2018; 6: e24-e25Summary Full Text Full Text PDF PubMed Scopus (23) Google Scholar Zika virus infection has emerged as a global threat in recent years, particularly because of its association with severe congenital deformities. Although the major topics of Zika virus research were discussed during a meeting of experts in Geneva, Switzerland, March 20–21, 2017, the reproductive age of men and women might be an interesting area that was not emphasised. Additionally, there are mounting data that suggest a role for female reproductive hormones in modulating infection with sexually transmitted diseases, including HIV,2Carias AM Allen SA Fought AJ et al.Increases in endogenous or exogenous progestins promote virus-target cell interactions within the non-human primate female reproductive tract.PLoS Pathog. 2016; 12: e1005885Crossref PubMed Scopus (22) Google Scholar while the concentration of androgens is suggested to increase the replication kinetics of hepatitis B virus.3Wang SH Yeh SH Lin WH Wang HY Chen DS Chen PJ Identification of androgen response elements in the enhancer I of hepatitis B virus: a mechanism for sex disparity in chronic hepatitis B.Hepatology. 2009; 50: 1392-1402Crossref PubMed Scopus (136) Google Scholar Presumably, Zika virus replication might be modulated by the reproductive hormones in both men and women. It is imperative to study the effects of hormones and age in the context of Zika virus infection, particularly because only male-to-female transmission has been reported.4Duggal NK Ritter JM Pestorius SE et al.Frequent Zika virus sexual transmission and prolonged viral RNA shedding in an immunodeficient mouse model.Cell Rep. 2017; 18: 1751-1760Summary Full Text Full Text PDF PubMed Scopus (133) Google Scholar Reproductive immunology could be another interesting area in which to investigate the sexual transmission of Zika virus. The long survival of Zika virus and its genome in the semen is suggestive of its higher replication in the male reproductive system.5Moreira J Peixoto TM Siqueira AM Lamas CC Sexually acquired Zika virus: a systematic review.Clin Microbiol Infect. 2017; 23: 296-305Summary Full Text Full Text PDF PubMed Scopus (186) Google Scholar Moreover, the absence of Zika virus in female genital samples might be due to its destruction because of the acidic vaginal environment. However, the pathophysiology of this virus in pregnant women suggests its higher replication in the female reproductive system as well. Being an enveloped virus, it would be interesting to study its differential gene expression in both sexes. A synergistic approach from all directions could help us to establish the pathway for the sexual transmission of Zika virus and possible interventions against it. I declare no competing interests. Investigating the sexual transmission of Zika virusThe sexual transmissibility of Zika virus, a pathogen that is transmitted primarily by aedes mosquitos, has important implications,1 particularly for women because infection during pregnancy causes adverse pregnancy and fetal outcomes, including microcephaly.2 WHO has included transmission through sexual intercourse and bodily fluids as a priority in its Zika Virus Research Agenda, which was a crucial component of the public health response to the 2015–16 Zika virus outbreak in South America. However, in the absence of methodologically rigorous population-based studies, the epidemiology of sexually transmitted Zika virus remains poorly understood. Full-Text PDF Open Access