A team of scientists took a position on considering Mpox a sexually transmitted disease (STD), not only because that was one of the main routes of spread reported in the last outbreak outside Africa, but also because that classification would enable adolescents to consult about the disease without the consent of their parents, while at the same time helping to direct public health messages, without falling into stigma.
This was stated in a review published in the journal Clinical Infectious Diseases and, to support the decision, they applied the Bradford Hill criteria . They argued that to take a position on the link between Mpox and sexual transmission, three important requirements are met: strength of association, consistency over time and geographic location and temporality. Here, the details.
Point
The global outbreak of the Mpox virus constituted an international public health emergency. Reports highlighted a temporal association between sexual activity and former monkeypox; an association between specific sexual practices and the location of lesion development; a high frequency of sexual practices that confer risk of other sexually transmitted infections among Mpox cases, that the virus can be isolated from sexual fluids and that isolated it is infectious, suggesting direct inoculation during sex. Finally, a growing body of evidence suggests that sexual transmission is the predominant mode of transmission of Mpox virus. Therefore, we conclude that Mpox is a sexually transmitted disease (STD).
Context
The US and the World Health Organization (WHO) had declared Mpox a public health emergency. Outbreaks in the past were short-lived and limited to endemic regions in Africa and transmitted through animals to humans, as well as through person-to-person exposure through close physical contact. However, since May 2022, the large Mpox outbreak in the US, Europe and now 110 countries worldwide has consistently highlighted the role of sexual transmission.
Basics
The understanding that Mpox is an STD is gaining more and more recognition, although labeling it as such is not in question. Sexually transmitted infections (STIs) are generally defined as those caused by an infectious microorganism that is transmitted from one person to another through bodily fluids (blood, semen, saliva, or vaginal, rectal, or urethral fluids) predominantly during oral, anal or vaginal sexual intercourse, as well as through direct skin-to-skin contact through macro- or micro-abrasions of the epithelium or mucous membranes during sexual activities.
Common sexually transmitted pathogens include human papillomavirus, human immunodeficiency virus (HIV), Neisseria gonorrhoeae , Chlamydia trachomatis , Treponema pallidum (the cause of syphilis), and herpes simplex virus types 1 and 2.
However, other pathogens that are predominantly transmitted through close contact, with insects and other animals as vectors as well as contaminated food or water, can also occasionally be transmitted through sex, including Ebola virus, Zika virus, and Shigella. These infections are considered sexually transmissible, but not STIs because the main mode of transmission is not sexual contact.
Therefore, the objective of the work was to synthesize the current scientific evidence, detailing the sexual transmission of the Mpox virus in the 2022 outbreak and also highlight the reasons why the identification of Mpox as an STD is justified and important.
The evidence that supports Mpox as an STD
The most commonly used framework for evaluating epidemiological evidence to determine causality is the Bradford Hill criterion, based on 9 aspects of epidemiological association: strength of association, consistency, specificity, temporality, biological gradient, plausibility, coherence, experimentation, and analogy. . The Bradford Hill criteria can be applied to the current body of epidemiological literature on the large Mpox outbreak in 2022 as follows.
Mpox, strongly related to sexual activity
There is a strong association between sexual activity and Mpox.
Eight different series published from 17 countries during the 2022 outbreak noted that between 84% and 100% of the 3,235 cases reported having had intercourse, most with a new sexual partner , before the onset of symptoms.
Additionally, during the 2022 outbreak, sexual practices associated with other STDs, such as multiple recent casual partners, attending sex parties, having group sex, and substance use during these practices without a condom were frequently reported among Mpox cases.
There also appears to be a temporal and anatomical association between reported sexual activities and disease manifestations; Recent receptive anal sex was associated with an increased risk of proctitis due to Mpox, and receptive oral sex in the days before diagnosis was reported in 95% of patients who developed tonsillitis due to this virus.
Another case series concluded that the 21 secondary cases (Mpox patients in whom the index case could be identified) were probably due to sexual transmission of 20 primary cases, while another report noted that 95% of the more than 500 cases of Mpox of the doctors who treated the patients thought the 2022 outbreak was sexually transmitted. Finally, among studies published during the current outbreak in the US and Europe, the proportion of cases with suspected non-sexual transmission ranged from 1% to 3%, further supporting the almost exclusive sexual spread of Mpox, at least within the US and Europe.
Therefore, according to the Bradford Hill criteria, the association between Mpox and sexual transmission so far meets three important requirements :
- Strong association
- Consistency over time
- Geographic location and temporality.
Why it is important to categorize Mpox as an STD
The ramifications of classifying Mpox as an STD are important for several reasons. Concerns have been raised that such classification would increase the stigma surrounding an already stigmatized disease, particularly among communities already affected by stigma and Mpox. Stigmatization can, in turn, lead to reduced health care seeking and partner notification, increasing disease transmission. However, it is important to highlight that public health messages have the ability to overcome stigma , analogous to the effective messages and public health strategies used during the latter part of the HIV pandemic.
By identifying populations at higher risk of infection, in this case homosexual, bisexual or other men who have sex with men, specifically those who have multiple partners or who participate in group sex, public health interventions such as vaccines, testing and Treatment can be adapted. For example, public health departments can support STI and HIV clinics to receive the resources needed to detect, treat, and prevent Mpox. Similarly, treatment guidelines and clinical education for STIs should be updated to formally include guidance on Mpox.
Additionally, understanding the primary mode of transmission can help facilitate focused community education and awareness programs , as well as enable behavioral modifications to reduce exposures, which in turn can increase outbreak control efforts and prove cost-effective. . As with other STDs, community and provider awareness is critical to disease control; Providers’ lack of knowledge about syphilis likely directly contributed to numerous missed cases and delays in diagnosis during the disease’s resurgence in the mid-2000s. By classifying Mpox as an STD, public health messages may change to ensure that the community and providers are aware of the disease, its manifestations and its risk factors. Additionally, it is essential that public health messages are clear.
Furthermore, given that more than half of all STIs in 2020 occurred among adolescents and young adults, Mpox is likely to affect some adolescents. Importantly, while in states like California minors ages 12 to 17 can consent to STD testing, treatment, and vaccination, such services are limited to only those diseases labeled as sexually transmitted. Treatment without the need for parental consent has the potential to greatly improve health-seeking behavior and linkage to care among minors. Confidential access to health care can also help reduce stigma about sexual health among minors, who are often embarrassed to reveal personal information to anyone, including their parents. Without labeling Mpox as an STD, adolescents who are at risk would be unable to seek treatment and prevention services without parental consent, which would limit the provision of such services and therefore exacerbate the risk of transmission among a already vulnerable population.
However, it is more important to consider the role of non-sexual transmission . With other STDs, when a child becomes infected, an appropriate concern for child abuse is raised. Similar concerns could be considered for children infected with Mpox virus. However, as discussed above, non-sexual transmission does occur. As of November 9, 2022, WHO reported 78,924 laboratory-confirmed cases in the 2022 outbreak, including 542 (1.2%) among people aged 0 to 17 years, of whom 141 (0.3%) were between 0 and 4 years. The 2003 Mpox outbreak in the US (which originated from prairie dogs infected with the virus) detected 11 cases among children in contact with an infected animal. The presentation in these children consisted of painful lymphadenopathy associated with diffuse smallpox lesions requiring hospitalization. Although remote in time, the difference in location of the rash and mode of acquisition may suggest that cases occurring among children are likely acquired by non-sexual routes . Therefore, caution should be taken to discern the route of transmission among the rare cases of Mpox that occur in children.
Similarly, while evidence of predominantly sexual transmission is evident for the recent outbreak in the US and Europe, historical outbreaks, even recent ones, within Africa have not consistently demonstrated that pattern of transmission. There remains conflicting evidence of sexual transmission of Mpox virus within Africa and therefore this classification currently applies predominantly to the 2022 outbreak in the US and Europe, but may inform the study of Mpox virus transmission dynamics. in other environments. Labeling Mpox as sexually transmitted may also have negative repercussions in settings with punitive policies for same-sex couples.
Conclusions
The current transmission dynamics of Mpox are very consistent with an ETS.
Recognition of Mpox as an STD should facilitate important public health interventions, including access to testing, treatment and vaccination, and other prevention interventions for affected communities. It is more important to remember that some diseases are not mere medical conditions but indicators of structural deficiencies and social dysfunctions. STIs are obvious examples of such dysfunction, driven by poverty, exclusion and other social determinants of health and health inequalities. Lessons learned from HIV and syphilis prevention should not be forgotten when addressing the rising wave of Mpox in the US and Europe. Individuals, communities, healthcare providers, public health programs, and decision makers must participate.
