Prevalence of Asymptomatic Mpox among Men Who Have Sex with Men, Japan, January–March 2023

Abstract

We prospectively assessed asymptomatic monkeypox virus infections among men who have sex with men in Tokyo, Japan, during the initial phase of the mpox epidemic. Our findings suggest that asymptomatic infections were likely underestimated and were comparable in magnitude to symptomatic infections, highlighting the need to improve testing accessibility among high-risk populations.

Multiple introductions of monkeypox virus to Ireland during the international mpox outbreak, May 2022 to October 2023

“…The availability of the large genomic epidemiological baseline from 2022 to 2023 described in this study will facilitate the delineation of transmission patterns and, specifically, the ability to distinguish imported from autochthonous transmission events as the priority must be to mitigate against further disease transmission by preventing the establishment of recalcitrant reservoirs arising from potential silent transmission, i.e. in asymptomatic cases [12], in different geographical regions which may seed further outbreaks. The dominant MPXV clade circulating in Ireland was suggested to accumulate mutations at a rate that was at least an order of magnitude higher than previously reported [28], which is consistent with recent data from a number of other studies [35,36].…”

“…were not determined, consequently limiting the transmission network inference. Secondly, the capacity to completely resolve the transmission networks by WGS may be limited by the possibility of asymptomatic mpox transmission [12]. Thirdly, differences in percentages of sequenced cases between countries impact the links that can be uncovered by the transmission analysis.…”

“…The mortality rate in the range 0.01-1.81% for Clade IIb associated with the 2022-23 epidemic [10], and up to November 2023, the mortality rate has been 0.18% (171/92,783) [11]. However, cases could be underestimated because of resource-poor healthcare settings and asymptomatic cases [12].…”

The prevalence of mpox and its association with sexual behavior among Chinese men who have sex with men in early August 2023

“…Contag et al, reported that of 1848 samples from 1645 individuals, there were 16 positive samples from 11 individuals in patients undergoing sexually transmitted infection (STI) screening in northern California from April to September 2022 19 . Mizushima et al, reported that the prevalence of asymptomatic mpox was 0.37% (5/1346) among MSM in Japan from January to March 2023 20 . The lack of relevant large‐scale epidemiological data on prevalence may be related to the changes of epidemic distribution and issues about privacy in China.…”

“…19 Mizushima et al, reported that the prevalence of asymptomatic mpox was 0.37% (5/1346) among MSM in Japan from January to March 2023. 20 The lack of relevant large-scale epidemiological data on prevalence may be related to the changes of epidemic distribution and issues about privacy in China. Mpox was prevalent in the American and European countries during early period, and then gradually spread to Asia in the multiple-countries mpox outbreak.…”