Masoud Keikha,Prashant Kesharwani,Amirhossein Sahebkar
Contradictory perspectives on the transmission route of human monkeypox during the 2022 outbreak
Contradictory perspectives on the transmission route of human monkeypox during the 2022 outbreak

Dear Editor, Monkeypox, caused by the monkeypox virus (MPXV), is a neglected tropical disease that remains endemic in African territories; however, there is an unprecedented silent multi-country outbreak that began in May 2022 in the European Union. Initial investigations in the European countries suggested the existence of undetected transmission chains, especially among men who have sex with men (MSM) [1]. At the time of writing, the World Health Organization (WHO) reports 82,147 laboratory-confirmed cases of monkeypox and 65 deaths in all WHO regions through December 2022. The MPXV 2022 primarily affects adult homosexuals; nevertheless, MPXV can also infect other populations, including children, pregnant women, as well as subjects with immune disorders [2,3]. There have been contradictory findings regarding the MPXV transmission routes in this outbreak. To this end, the study by Thornhill et al. concerning MPX and its potential sexual transmission, and the identification of monkeypox infection in women who had sex with men and non-binary individuals piqued our interest [4]. This is an intriguing document suggesting sexual intercourse as one of the transmission routes of monkeypox. In this regard, the WHO report indicated the presence of confirmed community transmission of MPX in certain non-endemic regions, namely North America, and Europe. It is hypothesized that MPXV infection could have occurred through accidental close sexual contact in regions with a high virus prevalence. In this regard, evidence such as a retrospective study in the United Kingdom demonstrated that all MPXV-infected patients were MSM [5]. Furthermore, the Centers for Disease Control and Prevention (CDC) reported that MPXV infection could be spread through direct contact with contaminated materials, contact with MPXV-infested surfaces, or even respiratory droplets [6]. LGBT populations may have multiple sexual contacts with more than one sexual partner over some time, the presence of asymptomatic MPXV infection among these cases was also possible. Asymptomatic MPXV infection supports transmission chains as boosters among LGBT + populations rather than to be a sexual transmission route [7]. Earlier, there is a sporadic case of MPXV infection in Israel, the corresponding case was presented lesions on his penis shaft following contact with MPXV-infected animals that imported from Africa [8]. Recently, Gould et al. published a report on the possibility of an airborne transmission route for MPXV infection [9]. Therefore, MPXV may be transmitted through close physical contact during sexual activity. Thornhill et al. detected MPXV-relevant DNA in tested vaginal swab samples; previous studies also observed the monkeypox DNA in urine, blood, or genital lesions [4]; however, the exact mechanism underlying this phenomenon remains unknown. The presence of monkeypox DNA in vaginal discharge and seminal fluids following viremia may result from passive diffusion or local replication. Surprisingly, Lapa et al. demonstrated the potential for cross-contamination from other sources (such as blood, urine, skin, feces, and nasopharynx) [10]. Cross-contamination may be associated with anogenital lesions characterized by prolonged virus particle shedding at elevated concentrations [11]. Consequently, this result must be interpreted with caution due to these limitations. Furthermore, the replication-competence of viral particles isolated from these clinical samples remains debatable [12]. There must be solid evidence concerning the assessed shedding of viable viruses in cell cultures. Although there was a high incidence of cutaneous lesions in the anogenital region, this could be coincidental; there is no academic explanation for the current distribution of cutaneous lesions in patients with monkeypox. From a different perspective, the WHO estimates that 38.4 million people are infected with HIV, with a prevalence rate of 51.3% among women. However, Thornhill et al. reported that HIV co-infection was present in only 27% of monkeypox cases [4]. In this study, no other sexually transmitted infections (STIs) were investigated. There is a need to establish a full STI workup for all patients with monkeypox to understand better the nature of MPXV transmission and other STI pathogens involved in the etiology of the lesions in the anogenital region, such as proctitis. Finally, the referred study was retrospective and had a small sample size; thus, there is a need for a large-scale investigation and additional reinforcement to advance our understanding of this mysterious phenomenon.

Masoud Keikha: Writing – original draft. Prashant Kesharwani: Writing – review & editing. Amirhossein Sahebkar: Supervision, Writing – review & editing.

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.