Longitudinal detection and clearance of mpox virus DNA in saliva and semen: a prospective cohort study

OBJECTIVES: Understanding the dynamics of mpox virus (MPXV) DNA detection in non-lesional compartments may help inform clinical management and sexual health counselling during mpox outbreaks. To describe the longitudinal detection and clearance kinetics of MPXV DNA in saliva and semen from individuals with confirmed mpox. METHODS: We conducted a prospective cohort study including 73 laboratory-confirmed mpox cases in Barcelona, Spain (May-September 2022). A total of 204 longitudinal samples (106 saliva and 98 semen) were analysed by quantitative PCR, and cycle threshold (Ct) values <35 were assessed over time. RESULTS: MPXV DNA was detected in 34% (36/106) of saliva and 27% (26/98) of semen samples. Median Ct values were lower in saliva than in semen. Viral DNA remained detectable up to day 56 in saliva and day 75 in semen after symptom onset, although Ct values <35 were observed only up to day 52 and day 38, respectively. Low Ct values were predominantly observed during the first 3 weeks, although some late samples showed relatively high viral DNA loads. Both PCR positivity and viral DNA loads declined over time. CONCLUSIONS: MPXV DNA may persist in saliva and semen beyond the acute phase of infection, with low Ct values observed in a subset of samples. Further studies incorporating viral culture are needed to clarify the clinical and transmission relevance of prolonged PCR positivity and to better inform public health recommendations.