Prolonged viral shedding in semen is associated with reproductive tract inflammation among men infected with Zika virus, according to results of a study published in the Journal of Infectious Diseases.
In this study, researchers evaluated semen samples obtained from men (n=49) with symptomatic Zika virus infection. Samples were collected at multiple time points to evaluate the duration of viral shedding, with long- and short-term shedding defined as shedding for more than 77.5 days and less than 22.0 days, respectively. The researchers aimed to characterize immunologic differences between samples obtained from patients who were long- vs short-term shedders. The samples were also evaluated for inflammatory markers.
Analysis of semen samples among the study population showed that 26 patients were long-term shedders and 23 were short-term shedders. With the exception of a higher incidence of joint pain in patients who were short-term shedders, no significant differences were noted in regard to age or symptoms between the 2 patient groups.
Stratified by viral shedding duration, significant differences were noted between patients who were long- vs short-term shedders in regard to Zika RNA viral load (P <.001), estimated duration of viral shedding (P <.001), and number of ejaculations in the week before sample collection (P =.02). For patients who were long-term shedders, the number of Zika RNA copies in semen was significantly negatively correlated with the number of days following symptom onset (P =.0002), suggesting that viral loads decreased as time post-symptom onset increased.
Further analysis showed that patients who were long-term shedders had significantly higher leukocyte counts at months 1 (P =.001) and 2 (P =.03) following symptom onset compared with those who were short-term shedders. Of note, leukocyte count was significantly negatively correlated with time post-symptom onset for only patients who were long-term shedders (P =.0002). Patients who were long-term shedders also had significantly higher sperm counts within the first month following symptom onset (P =.02).
Among all possible comparisons, seminal cytokine levels were correlated in 53.8% of comparisons among patients who were long-term shedders compared with 18.2% for those who were short-term shedders.
The researchers also noted higher inflammatory cytokine concentrations among patients who were long- vs short-term shedders. This finding combined with the comparatively higher leukocyte counts observed in patients who were long-term shedders suggests prolonged viral shedding is significantly associated with reproductive tract inflammation in men.
This study may have been limited by its small simple size.
In regard to these findings, the researchers concluded that “this knowledge is crucial to reduce [Zika virus] spread and incidence of congenital [Zika virus] syndrome.”
Vogt MB, McDonald EM, Delorey M, et al. Prolonged shedding of Zika virus in human semen is associated with male reproductive tract inflammation. J Infect Dis. 2022;jiac329. doi:10.1093/infdis/jiac329