Stop Mpox

We aimed to assess the prevalence of asymptomatic cases of monkeypox virus (MPXV) infection and cases with mild unrecognized Mpox symptoms, among gay, bisexual, and other men who have sex with men and trans women (TW), using a self-sampling strategy. Anal and pharyngeal swabs were tested by MPXV real-time PCR and positive samples inoculated into Vero E6 cells, which were subsequently checked for cytopathic effect (CPE). 113 individuals participated in the study, 89 (78.76%) were cis men, 17 (15.04%) were TW. The median age was 35.0 years (IQR: 30.0-43.0), 96 (85.02%) individuals were gay or bisexual and 72 (63.72%) were migrants. Seven participants were MPXV positive (6.19% (95% CI: 1.75%-10.64%)). Five tested positive in pharyngeal swabs, one in anal swab and one in both. Six did not present symptoms recognized as MPXV infection. Three samples were positive for CPE, and showed anti-vaccinia pAb staining by FACS and confocal microscopy. We describe Mpox cases that remain undiagnosed and show reproductive virus and who might be able to infect others. Restricting testing to individuals reporting Mpox symptoms may not be enough to contain outbreaks.