FormalPara Key Points

The monkeypox virus (which causes mpox) has potential to be spread between athletes in contact sports (i.e., substantial direct skin-to-skin contact).

Mpox may produce similar signs and symptoms to other infectious skin diseases that are common in contact sports, which may make accurate diagnoses of skin lesions in athletes more challenging.

The likelihood and/or magnitude of a sports-related mpox outbreak may be reduced by educating stakeholders on mpox risk, clinical recognition, and appropriate management (including sports participation guidelines for athletes exposed to, suspected to have, or diagnosed with mpox).

1 Introduction

The 2022 mpox outbreak (caused by the monkeypox virus) made global headlines and caused the World Health Organization (WHO) to declare a global emergency on 23 July, 2022 [1]. Epidemiologic data have revealed mpox transmission occurs primarily through skin-to-skin contact. The 2022 outbreak was primarily in men who have sex with men [2], and this at-risk group was been the focus of media coverage. However, there is significant potential for monkeypox virus to spread through non-sexual contact within sports settings, as other infectious skin diseases frequently do (especially in contact sports). Thus, the urgent need for action to control mpox outbreaks [3] must proactively educate sports stakeholders and address disease transmission in the athletic community. This Current Opinion briefly reviews infectious skin disease transmission in sports and relates this to the 2022 mpox outbreak. It then provides recommendations for recognizing and managing athletes with mpox, proposes guidelines for sports participation following mpox exposure or diagnosis, and discusses strategies for reducing the risk of outbreaks in sports settings.

2 Infectious Skin Diseases in Sports

To understand the risk for monkeypox virus transmission (and mpox outbreaks) in sports settings, one must recognize the risks for other infectious skin diseases in athletes. Bacterial, fungal, and viral skin diseases are common in sports that include significant close contact [4]. Wrestling is the sport that is most notorious for skin infections and will serve as the primary focus of this paper, but football, rugby, and martial arts athletes are also highly susceptible. Skin infections account for 8.5% of adverse events in high school and 20.9% in college wrestlers [5]. The most common viral skin infection in this population is the herpes simplex virus one (HSV-1) variant Herpes gladiatorum. The prevalence of Herpes gladiatorum varies between studies, but polymerase chain reaction testing revealed approximately 30% HSV-1 seropositivity in a high school wrestling camp [6]. Various other skin diseases are common in the wrestling community, including tinea and Staphylococcus aureus.

Like mpox, skin-to-skin contact is the primary mode of transmission of infectious skin diseases in wrestling and other high-contact sports. The high prevalence of HSV-1, combined with low awareness of one’s contagiousness, is the key factor in transmission. Considerable efforts have been directed at sanitizing equipment (e.g., gym mats), but fomites are an unlikely source of spread of HSV-1 [7]. However, fomite transmission of other infectious skin diseases has been documented in athletes (e.g., tinea in members of a judo team that shared an electric shaver) [8]. Though the aforementioned high-contact sports have the greatest risk of infectious skin diseases, infectious skin diseases are reported in a wide variety of athletes, albeit less commonly [9].

Serious outbreaks of infectious skin diseases in high-contact sport settings have been reported in the medical literature since the 1960s [10,11,12,13]. As an example, 60 of 175 (34%) high school wrestlers were diagnosed with HSV-1 at a summer training camp in 1964 [10]. In the decades since, similar outbreaks have caused numerous wrestling camps to be shut down, despite greater awareness of the issue and guidelines for prevention [7]. Approximately 80% of wrestlers with skin infections are evaluated by a physician and about two-thirds of those infected return to wrestling in less than a week [5]. There is evidence that vigilance in recognizing infectious skin disease and the implementation of prevention strategies (i.e., prophylactic treatment for HSV-1) can markedly reduce the incidence of skin disease in wrestling camps [14].

Infectious skin disease outbreaks that began within the men who have sex with men community, such as methicillin-resistant Staphylococcus aureus, eventually spread into athletic settings and gyms [15, 16]. The very first community-acquired methicillin-resistant S. aureus outbreak in wrestling was reported in 1998 [17], and within less than two decades the incidence was reported to be as high as 1–2.5% of wrestlers and approximately 0.75% of football players [18]. Wrestlers with methicillin-resistant S. aureus then spread infection to non-athletes [17]. Given all of the above, it is reasonable to suspect that contact sports could emerge as a setting for monkeypox virus transmission, and that purposeful prevention strategies must quickly be developed to reduce the risk of outbreaks in athletes.

3 Overview of Monkeypox Virus and Mpox

3.1 Terminology

Monkeypox virus causes an infectious skin disease that was originally discovered in monkeys in 1959 [19]. On 28 November, 2022, the WHO recommended renaming the disease caused by the monkeypox virus from “monkeypox” to “mpox” [20]. The International Committee on Taxonomy of Viruses may rename the monkeypox virus (and others within the same family) in 2023 [21]. Thus, this paper uses “monkeypox virus” to refer to the pathogen, and “mpox” to refer to the clinical disease. Monkeypox virus is commonly abbreviated as “MPVX” but given its similarity to mpox, this paper will use the full term instead to avoid confusion.

3.2 Brief History and Epidemiology

Monkeypox virus belongs to the genus Orthopoxvirus within the poxviridae (pox viruses) family. The genus includes the variola virus (which causes smallpox) and cowpox virus (originally used by Edward Jenner to develop a smallpox vaccine). It should be noted that chickenpox (which can appear similar to mpox [22], see Sect. 5.2), is a herpesvirus, not a pox virus. Unlike the smallpox virus, which was exclusively spread through human-to-human transmission, monkeypox virus is zoonotic (infects animals and can be spread to humans). A number of rodent and non-human primate species are suspected to be reservoirs for monkeypox virus, but details remain unknown [22]. There is concern that monkeypox virus could spread to domesticated animals and wildlife outside of historically endemic countries, and become endemic in new regions leading to sustained transmission [23,24,25].

The first known case of mpox in humans was identified in 1970 in a 9-month-old child in the Democratic Republic of Congo, and was originally mistaken for smallpox owing to the very similar clinical presentation (fever, hemorrhagic skin lesions, lymphadenopathy) [19, 26]. Monkeypox virus is endemic in the Democratic Republic of Congo and other African countries, and there are two distinct clades: Central African (10.6% mortality rate) and West African (3.6% mortality rate) [27].

In the 1980s, there were ~ 357 reported cases in the African continent. Confirmed and suspected cases have steadily increased since then, and outbreaks have occurred in non-endemic countries [27]. In endemic countries, monkeypox virus primarily infected young children (median age = 4 years) in the 1970s and then became more common among adolescents and young adults (median age = 21 years) in the past decade [27]. The steady growth in human monkeypox virus infection rates is likely related to decreased immunity to smallpox, following the disease’s eradication in 1980 and limited exposure to other pox viruses that could provide cross-immunity [28]. A detailed account of mpox epidemiology is beyond the scope of this paper, but is available elsewhere [26, 27, 29].

4 Why Mpox Matters for Athletes and the Sports Community

Infectious skin diseases are common in contact sports (i.e., wrestling and other combat sports, football, rugby) [7, 30], but also occasionally present in other types of athletes [9, 31,32,33,34,35]. Misdiagnosis (and thus, inappropriate management) of infectious skin diseases in athletes is already commonplace [7, 30, 36], and the rise of mpox adds yet another challenge when an athlete presents with skin lesions (see Sects. 5.2 and 5.3). Public concerns about mpox risk from sports participation have already surfaced [37, 38] and will likely remain as long as the disease persists. Thus, it is important for stakeholders in the sports community to understand the implications of having an mpox infection.

4.1 Mortality Risk

Mpox can cause clinical illness nearly identical to smallpox, in that it features a diffuse pustular rash (see Sect. 5.1), and has had a historically high fatality rate in endemic regions [22]. However, comparison with smallpox is not especially meaningful to most current athletes (or sports stakeholders, including clinicians), as smallpox was eradicated in 1980. Mpox fatality rates have been reported to range from 0 to 11%, but the higher rates must be considered in context. Data from the Democratic Republic of Congo acquired from 1981 to 1986 revealed 338 mpox cases, and all fatalities were children aged ≤ 8 years, who were not vaccinated for smallpox [39]. A meta-analysis of 1958 patients with mpox from 12 studies revealed a ~ 35% hospitalization rate, and of those, a ~ 4% case fatality rate. All deaths were in African patients [40], but it is not clear if this was due to healthcare disparities or other factors. In the 2022 global outbreak, there were a limited number of deaths outside of Africa. As of 25 November, 2022, only 14 deaths were reported in patients with mpox in the USA (0.05% of confirmed cases) [41] and many of these were in patients who were HIV positive or had AIDS [42]. Thus, the risk of death for immunocompetent individuals in non-endemic countries seems minimal and should not be used to incentivize athletes and sports organizations. Rather, the clinical implications (described below) may be used to incentivize athletes to take mpox seriously.

4.2 Morbidity

Mpox typically causes a systemic illness (see Sect. 5.1), but it may be valuable to emphasize that mpox can also have serious complications. An overall 35% hospitalization rate is reported in the literature, with a 10% hospitalization rate in European patients [40]. Reports from the 2022 outbreak describe some hospitalizations of 2–5 weeks in duration [43]. Such long hospitalization periods would clearly be detrimental to athletes, but it is uncertain if healthy athletes (especially high school or college age) would have such a high likelihood of hospitalization. One available dataset for adolescent (age 13–17 years) patients with mpox (n = 12) reveals no complications or hospitalizations [44], but a US Centers for Diseases Control and Prevention (CDC) report describes six hospitalizations of 55 adolescent patients with mpox [45].

The 2022 mpox outbreak included some unique and atypical clinical manifestations compared with historical reports, and thus the range of risks remains somewhat unknown. Encephalitis has been described as a complication of mpox in endemic regions (one case out of 282 patients in Zaire, 1980–5) [46], in the 2003 US outbreak (one patient) [47], and the 2022 outbreak (two cases of encephalomyelitis in the USA) [48]. The two cases of mpox-caused death reported in Spain were due to encephalitis, which happened in previously healthy, immunocompetent male individuals [49]. Case reports describe previously healthy 31-, 32-, 34-, and 37-year-old male individuals who developed symptomatic myocarditis, seemingly attributable to mpox [50,51,52]. It is noted that some (not all) of these patients had a past history of syphilis and were taking HIV pre-exposure prophylactic medications. Another case report describes a previously healthy 51-year-old male individual with pericarditis and mild pericardial effusion attributable to mpox [53]. Pain (especially for those with anogenital lesions) and secondary bacterial infections are common reasons for hospitalization [54]. It is difficult to know how likely the risks of these severe complications would be in healthy athletes, especially if athletes obtain it from non-sexual contact (the majority of cases in the 2022 outbreak) and if morbidity is dependent on the mode of transmission ([55], see Sect. 5.1).

4.3 Implications for Sports Participation and Performance

It may be challenging to get stakeholders to recognize the seriousness of mpox and adhere to disease prevention recommendations, especially if the possibility of severe illness seems low. Therefore, it may be beneficial to emphasize that contracting mpox can result in significant time lost from sport participation, which can impair training progress (or cause detraining) and result in missed competitions. Such recognition may incentivize athletes to follow protocols to minimize risk.

Mpox can cause some symptoms that are particularly unfavorable for competitive athletes including fatigue (60% of reported cases), muscle pain (45%), joint pain (26%), and dyspnea (25%), as well as a number of other unpleasant effects [40]. Athletes with infectious skin diseases are generally not allowed to participate in contact sports until the signs and symptoms have resolved, and this should hold true for mpox (see Sect. 6.1). Mpox is symptomatic for 2–4 weeks [29]. In contrast, approximately 80% of wrestlers with skin infections (prior to the current mpox outbreak) are evaluated by a physician and about two-thirds of those infected return to wrestling in less than a week [5]. The mpox symptomatic period is also longer than typical influenza and similar to sudden acute respiratory syndrome coronavirus 2 (SARS-CoV-2,) in elite athletic populations [56].

5 Considering Mpox in Athletes with Skin Lesions

Athletes who can expose others to potentially infectious skin diseases (mpox or other) should be withheld from sports participation until evaluated by an appropriately trained medical professional (see Sect. 6). A thorough review of the presentation, diagnosis, and management of mpox is beyond the scope of this paper, but is available elsewhere [22, 39, 40, 43, 57]. This section presents a summary of these considerations, while providing some recommendations specific to sports settings.

5.1 Clinical Presentation

The typical course of mpox involves a 10- to 14-day incubation period, a 2-day prodromal period (general malaise, musculoskeletal pain, headache), and then a diffuse maculopapular rash (skin lesions referred to as exanthems) [22, 41]. Most patients (> 70%) develop a fever [40]. The rash progresses from macular (flat discolored region of skin), to papular (raised discolored region of skin), to vesicular (fluid-filled blisters), to pustular (pus-filled blisters) and eventually forms a crust/scab [41]. Lesions in all of these stages are ≤ 1 cm in diameter, and in the later stages have umbilications (necrotic center). Additionally, mucous membrane lesions (enanthems) can occur (prior to, with, or after exanthems appear), and these can result in pain and/or bleeding at the respective site [41]. Readers are encouraged to visit available resources to see example images of mpox lesions [41, 43, 58, 59].

Throughout the 2022 outbreak, the clinical presentation of mpox varied and numerous atypical cases were described. The prodromal period is sometimes completely absent, or its symptoms occur concurrently with the rash [41, 60]. Lymphadenopathy has previously been described as a clinical sign that differentiates mpox (where it is present) from smallpox (where it is absent); however, lymphadenopathy did not occur in all cases in the 2022 outbreak (absent in ~ 42–44% of cases in two different reports) [60, 61]. Some patients in the 2022 outbreak had relatively localized lesions or even a single lesion (11% of cases in two different reports) [60, 61], which contrasts with the more widespread lesions historically reported.

Clinical presentation may depend on the nature and site of exposure [55]. Anogenital and oral lesions were commonly reported in the 2022 outbreak, which was predominantly in men who have sex with men sexual activity. However, one case report describes mpox lesions arising at the site of a tattoo (7 days after the procedure) [62] and two case reports describe an initial mpox lesion appearing at the site of an occupational needlestick [63, 64]. Thus, it is possible that mpox lesions could follow similar regional patterns as HSV if transmitted via sports-related contact (e.g., similar to the face and neck in wrestlers [4, 7, 9]).

5.2 Differential Diagnoses in Athletes

Healthcare providers who work in a sports setting (e.g., sports physiotherapists, sport medicine physicians, athletic trainers) may be the first point of contact for evaluating skin conditions in athletes, rather than a dermatologist or an infectious disease specialist. Skin infections in athletes are already commonly misdiagnosed and incorrectly managed (e.g., HSV infections being mistaken as bacterial infections [30]), and thus mpox exacerbates existing diagnostic challenges.

Mpox can be mistaken for different herpesvirus infections, including both HSV and varicella zoster virus (VZV, commonly referred to as chickenpox as a primary infection and shingles when reactivated). Mpox typically includes a higher grade prodromal fever than VZV, and is typically (but not always, see Sect. 5.1) accompanied by lymphadenopathy [65,66,67]. Systemic prodromal symptoms (e.g., fever, malaise, anorexia) often occur during primary HSV infections, and localized prodromal symptoms may occur in primary infections and reactivations (e.g., burning/tingling sensations in the affected region of skin) [68, 69]. Primary HSV infection may begin with localized lesions, which then spread, whereas reactivated HSV lesions are generally localized (i.e., confined to a single dermatome) [70]. Mpox lesions are clearly demarcated, typically appear at the same stage for a given body region (exceptions noted in the 2022 outbreak), and progress slowly (1–2 days) through each stage, whereas VZV lesions have a more irregular border, can all be at different stages, and crust over more rapidly (≤ 24 h after a given macule first appears) [65,66,67].

Mpox may also be misdiagnosed as another member of the poxviridae family, molluscum contagiosum virus (which is of the genus Molluscipoxvirus). Molluscum contagiosum produces 3- to 5-mm umbilicated papules, each of which persists for approximately 2 months [71]. Typically, fewer than 20 lesions are present at a time, but many more may occur in some cases [71]. As the virus spreads to different regions of the skin, new lesions arise and allow the disease to persist for months or years. Molluscum contagiosum only affects the skin (and sometimes mucous membranes), so there is no symptomatic prodromal period and it does not cause any systematic effects [71]; this may differentiate it from mpox (and the aforementioned herpesvirus infections). Thus, the presence of prodromal or concurrent systematic signs/symptoms should suggest that molluscum contagiosum itself is not the culprit responsible for skin lesions.

Clinicians should already be familiar with how these viral skin diseases differ from common bacterial and fungal skin infections, as well as cutaneous manifestations of other diseases. Thorough reviews of skin conditions in athletes are available elsewhere [4, 30, 31, 36, 72, 73]. Mpox can also resemble a number of other conditions that are not specifically linked to sports participation (e.g., syphilis), a thorough description of such is beyond the scope of this paper.

5.3 Mpox Diagnosis

It can be difficult for healthcare providers to achieve the delicate balance between being prudent in recognizing the possibility of mpox versus haphazardly ordering mpox diagnostic testing on all athletes’ skin lesions. Deciding who to test is challenging, given the reports of misdiagnoses of atypical mpox presentations [65, 74, 75]. While it is necessary to consider laboratory testing for monkeypox virus, it is also important to consider the prior probability of mpox infection, based on clinical signs/symptoms and possible exposure. For example, a wrestler who develops new-onset skin lesions after exposure to a wrestler with known HSV lesions is more likely to be showing signs of HSV, rather than mpox. The CDC warns against unwarranted testing and reports three cases of false-positive tests for monkeypox virus in individuals who had no known exposures and cutaneous symptoms that were inconsistent with mpox lesions [76].

5.3.1 “Suspected” and “Probable” Cases

The CDC [77] or WHO [78] criteria for “suspected” and “probable” cases should be used to guide decisions regarding whether diagnostic testing for mpox is warranted in athletes. These definitions are available on the organizations’ respective websites and are regularly updated as new information emerges.

In brief, the WHO [78] classification of a “suspected case” can be summarized as a patient who has:

  1. (1)

    signs/symptoms of systemic illness (i.e., prodromal period) following exposure to a probable or confirmed patient with mpox; OR

  2. (2)

    an “unexplained acute rash, mucosal lesions, or lymphadenopathy” and the skin lesions cannot be explained fully by other viral or bacterial skin conditions.

The CDC [77] classifies a “suspected case” as a patient who has:

  1. (1)

    a new rash characteristic of monkeypox; OR

  2. (2)

    a high clinical suspicion for mpox AND meets epidemiological criteria for the exposure risk.

The CDC’s epidemiologic criteria can be summarized as: (1) contact with individuals with suspected/probable/confirmed mpox; (2) close/intimate contact within a “social network experiencing mpox activity;” (3) travel to a monkeypox virus endemic region; and (4) contact with wildlife reservoirs of monkeypox virus [77]. The WHO utilizes similar epidemiological criteria for its definition of a “probable case” [78]. Both the CDC and WHO also include positive non-mpox-specific orthopoxvirus diagnostic testing results in their “probable case” definitions [77, 78].

As new data emerge, these definitions may evolve and include other epidemiologic criteria. For instance, BMJ Best Practice identifies similar risk factors as the WHO and CDC, but also includes “recent tattoo or piercing” [79]. Evidence of mpox transmission through body art is based on data from July to August 2022 and was published in the following month, [62, 80], but this risk factor is not mentioned in the CDC or WHO epidemiologic criteria. Assessing an athlete to determine if they have a “suspected” or “probable” case of mpox does require healthcare providers to request very personal information regarding sexual behaviors and honest responses from the patient.

5.3.2 Laboratory Diagnostic Testing

If mpox is suspected or probable, the appropriate public health agencies should be contacted so that proper channels for diagnosis and reporting can be followed. Suspected/probable cases of mpox are evaluated/confirmed using laboratory testing. A thorough description of these procedures is beyond the scope of this text, but available elsewhere [81]. In brief, samples are collected from lesions and/or exudates and then submitted to a laboratory to be tested for monkeypox virus nucleic acids using polymerase chain reaction. Analysis of specimens from multiple sites may improve the accuracy of diagnostic testing [82].

5.4 Treatment

There are currently no drugs approved by the US Food and Drug Administration (FDA) for the treatment of mpox. However, tecovirimat (also known as Tpoxx® and ST-246) is FDA approved for treating smallpox and is recommended for the treatment of mpox under the FDA’s expanded access investigational new drug protocol. However, there are many nuances to consider. Smallpox was eradicated when tecovirimat was developed, and its FDA approval was based on its efficacy in laboratory animal trials (including monkeypox virus) and its safety profile in healthy humans, but not its efficacy in treating human disease [83, 84]. At the time of writing, there are no published randomized clinical trials to describe the efficacy of tecovirimat in mpox management. Since the 2022 mpox outbreak, a number of clinical trials have been initiated to test the safety and efficacy of the drug in patients with mpox. Preliminary data (without a control group) suggest that it is generally safe and well tolerated in patients with mpox [85]. Currently, the CDC recommends tecovirimat for patients with severe disease and for patients with lesions in “anatomic areas which might result in serious sequelae that include scarring or strictures” and those at the highest risk for severe disease (immunocompromised patients, young children, pregnant and lactating female individuals, those with pre-existing skin disease) [86]. Other treatments for severe mpox include cidofovir (FDA approved for treating cytomegalovirus), brincidofovir (prodrug of cidofovir, FDA approved for treating smallpox) and intravenous vaccinia immune globulin (for treating complications of a vaccinia vaccination) [87].

It is important to differentiate mpox from aforementioned herpesviruses, as HSV and VZV are managed with acyclovir or valacyclovir [88, 89], neither of which are effective in the management of mpox (or other Orthopoxvirus diseases) [90]. As described in Sects. 5.1 and 5.2, the rise of atypical mpox throughout the 2022 outbreak makes it increasingly difficult to confidently differentiate between mpox and other conditions that produce skin lesions based on the clinical presentation alone [81], and this makes inappropriate pharmacological management more likely. As an example, a November 2021 mpox case in USA (which preceded the 2022 outbreak) was originally diagnosed as varicella and treated as such, until a histopathologic examination of a pustule biopsy suggested otherwise [74]. Other case reports describe mpox originally being suspected to be HSV, and (inappropriately) treated as such [75]. There are insufficient data to determine if mismanagement with incorrect antiviral therapy has adverse effects. Likewise, the effects of delaying tecovirimat therapy are uncertain, as the drug’s efficacy remains unknown.

6 Sports and Exercise Participation Guidelines for Mpox Infection and Exposure

At the time of writing, most sports organizations have not provided publicly available plans to address mpox cases or outbreaks. However, management for herpesvirus infections provide a good general framework for how clinicians should approach suspected cases of mpox in athletes. The National Federation of State High School Associations [91] and National Collegiate Athletic Association [92] have developed rules and guidelines for the removal and return to participation of athletes with HSV (and various other infectious skin diseases). Readers are referred to the original documents [91, 92] and other sources that reference them [4, 7, 30] for the detailed diagnosis and management of other skin conditions in athletes.

6.1 Example Guidelines for HSV Infection

The National Federation of State High School Associations recommends athletes with a primary HSV infection be removed from participation in contact sports immediately [91]. Infected athletes should be withheld from participation for at least 10 days (or 14 days if systemic illness and/or lymphadenopathy is/are present) if treated or until all lesions are healed (with intact crusts/scabs), there is an absence of new lesions for 72 h, and there is resolution of lymphadenopathy. An HSV reactivation requires 120 h of pharmacological treatment and non-participation. Similar recommendations are in place for VZV. The National Federation of State High School Associations requires athletes who were exposed to the infected athlete through direct contact in the prior 3 days to be removed from contact activity for a minimum of 8 days and to undergo a daily evaluation for new skin lesions. This evaluation can be done by a “knowledgeable coach or appropriate health-care provider.”

The National Collegiate Athletic Association has a similar (but not identical) policy for wrestlers with HSV infections. However, the National Collegiate Athletic Association policy has more stringent guidelines regarding the medical oversight, which include a team physician or certified athletic trainer to perform medical evaluations, appropriate lighting, and standardized documentation [92]. Both organizations emphasize that covering the infectious skin lesions is not sufficient to allow participation [91, 92]. These guidelines/rules are specific to contact sports, but clinical judgment should be utilized for participation decisions in sports without excessive skin-to-skin contact (i.e., does participation with the skin infection pose a significant risk to the infected athlete, other teammates, competitors, or officials?).

6.2 Proposed Sports Participation Guidelines for Mpox Infection and Exposure

The HSV guidelines above may be modified for suspected/probable/confirmed mpox cases, such that athletes with any suspicious lesions are immediately withheld from practice and competition until a further evaluation by a qualified medical professional. Mpox exposure itself is not reason to remove an athlete from sports participation. Until October 2022, it was thought that mpox could not be transmitted by pre-symptomatic individuals (i.e., during incubation period), but emerging evidence suggests that pre-symptomatic transmission is possible, or even likely [93]. However, pre-symptomatic transmission is only described through sexual intercourse and it is possible that internal mpox lesions (i.e., rectal enanthems) are present during that time, but patients are not aware of them yet [93]. Thus, the current evidence continues to suggest that individuals without clinical signs and symptoms (visible skin lesions, systemic illness) would be an unlikely source of infection in athletic settings.

Suggested guidelines for athlete participation are provided in Table 1. These are based on the CDC’s current recommendations following exposure [94, 95], as well as the UK Health Security Agency’s protocol for de-isolation and discharge of patients with mpox [96]. These sports and exercise participation guidelines are based on the most current information at the time of writing and may need to be updated as more data become available.

Table 1 Recommended guidelines for athletes with new-onset skin lesions, confirmed mpox diagnosis, and exposures to mpox
Full size table

6.3 Exercise Restrictions

There are no available data to guide exercise recommendations for patients with mpox or other systemic Orthopoxvirus infections. There are some data available regarding the effects of exercise during upper respiratory tract infections [97], but this may not be relevant to systemic viral infections such as mpox. Likewise, expert opinion has suggested that exercise training be discontinued during SARS-CoV-2 infection [98], especially given the concern regarding myocarditis [99]. Cardiac complications do exist for mpox [50,51,52,53], but the epidemiology of such is relatively unknown.

Pain and systemic illness may limit one’s motivation for exercise during the initial stages of mpox infection, but this is not documented. It is not known if significant movement could exacerbate lesions, or if sweat could modulate autoinfection of skin lesions or the risk of secondary bacterial infection. In the absence of data regarding exercise during mpox, it seems reasonable to take a conservative approach and recommend exercise restriction until no new lesions have appeared in the past 48 h, all lesions have crusted over, and all signs/symptoms of systemic disease have resolved.

7 Mpox in Athletes: Past, Present, and Future

To the author’s knowledge, there were no reported mpox cases attributed to sports participation in the 2022 outbreak. Past mpox outbreaks outside of endemic countries have not been reported to enter the sports community, although one case has been attributed to attending a football camp [100]. However, the recent outbreak was far more widespread than previous outbreaks. As of 29 November, 2022, the CDC reported 81,225 cases in countries that have not historically reported mpox, with 29,325 in the USA alone. [41] In contrast, fewer than 100 cases of likely or confirmed mpox were identified in the 2003 outbreak [29, 41]. The 2022 outbreak appears to have peaked in July/August; however, cases still continue to emerge daily.

The lack of sports-related cases is likely to be attributable to limited participation in contact sports during the apparent peak of the 2022 mpox outbreak (during the summer, when most contact sports were out of season in Europe and North America). At the time of writing, the majority of patients with mpox are beyond school/college age (median age ~ 35 years) and lesions are primarily in the anogenital region [101], and therefore there is limited exposure to infection in the high school/college sports community.

Throughout the academic year, it is likely that more students will be exposed to the virus (e.g., through sexual/intimate activity). Indeed, recent reports describe mpox cases in children and adolescents [45]. For adolescents with known exposure data in the USA (n = 35), nearly all cases are traced to sexual contact. However, there are a number of US cases attributable to non-sexual skin-to-skin contact and fomite transmission (e.g., sharing a bed, living in the same household but without direct contact). Likewise, nine of the 12 adolescent cases in Spain were attributable to non-sexual contact (with many linked to piercing studios) [44]. These cases emphasize that mpox is entering school-age individuals and the reality of non-sexual transmission. If a sufficient number of high school/college students contract mpox, it is inevitable that this will eventually include some student athletes in contact sports. This will increase the risk for outbreaks within (i.e., from practices) and between (i.e., from games/tournaments) teams, and transmission to other members of the community.

8 Reducing the Risk of Mpox Outbreaks in Athletes

8.1 Surveillance and Education

Collaboration between public health organizations, sports governing bodies and their stakeholders, and experts in infectious disease epidemiology will be necessary for developing appropriate guidelines to prevent or mitigate mpox outbreaks in athletes. The SARS-CoV-2 pandemic provides examples of both successful and unsuccessful disease transmission prevention within sports [102]. Daily testing, sophisticated contact monitoring/tracing, and continually updated evidence-based guidelines were instrumental in successfully reducing the spread of SARS-CoV-2 in professional sports leagues [102]. Similar mpox-focused procedures can readily be implemented into high-risk sports, and the guidelines provided (Sect. 6 and Table 1) may help reduce the risk of mpox exposures.

Medical personnel associated with at-risk sports may need to advocate to administrators and other stakeholders the case for stricter adherence to guidelines aimed at reducing the risk of infectious skin diseases in athletes. For instance, skin checks are supposed to be incorporated into wrestling practices and events, but in practice these may be performed by non-medical personnel and are often recommended on a weekly basis [5], which may be too infrequent during a mpox outbreak. All medical personnel involved in contact sports should receive proper training on identifying potential cases of mpox to avoid a misdiagnosis and should conduct skin checks themselves whenever possible. Clinicians should err on the side of caution, by having a broad definition to for identifying suspected cases for further evaluation [103].

It is essential to educate all stakeholders within the athletic community (especially high-risk sports), including athletes, parents, coaches, administrators, medical personnel (i.e., athletic trainers, physical therapists, team physicians), and other affiliated personnel (e.g., massage therapists, strength and conditioning coaches) on mpox, how it compares to other infectious diseases, and the importance of preventing outbreaks. This may help individuals identify mpox before sports-related exposures take place and cause an outbreak.

8.2 Vaccination

Pre-exposure mpox vaccines are receiving attention for those with occupational risks [104, 105], but it is premature to recommend them for athletes. The WHO supports vaccination as a method to complement other public health measures (e.g., surveillance, early diagnosis, isolation, and contact tracing) to manage the response to mpox [106]; these other methods can be readily utilized within sports settings. Prioritizing those at the highest risk of exposure and severe illness remains a priority in the face of limited vaccine availability. As of 16 November, 2022, the WHO does not recommend mass vaccination, and only recommends pre-exposure vaccination for individuals with the greatest exposure risk (i.e., healthcare workers and researchers with repeated exposures to patients with mpox or monkeypox virus, individuals with multiple sexual partners) [107]. There is also an ethical case for prioritizing vaccines for those from endemic regions where the data used to develop vaccines originated [104]. Off-label use of smallpox vaccines does provide protection against mpox, but is not without risk [108], and a newly approved mpox vaccine is available but its efficacy is unknown [104]. If outbreaks within athletic communities do arise, public health agencies can help determine if ring vaccination (vaccinating close contacts and exposures) is helpful, and explore if future pre-exposure vaccination programs are warranted.

8.3 Disinfection

While fomites seem to be a limited risk for HSV-1 (as described previously), fomite transmission may be a possible source of transmission for monkeypox virus. Hospital care workers have apparently contracted mpox from handling contaminated bedding of patients with open sores during a previous outbreak, and recent research reveals high viral loads on inanimate objects (i.e., chairs, towels) in patient rooms [109]. It would be expected that fomite transmission would be less likely in non-hospitalized patients without obvious lesions. Indeed, this is the setting that is created when high-contact athletes undergo appropriate pre-participation skin checks and are removed from participation until a further evaluation for any suspicious lesions.

Regardless, sports organizations should be sure to follow existing sanitation recommendations and equipment sharing should be minimized whenever possible. When sharing of equipment is unavoidable (e.g., weight benches at gyms, wrestling mats, treatment tables), standard disinfection procedures should be followed as part of good general hygiene. Additionally, in athlete-focused healthcare settings (e.g., sports physiotherapy clinics), adherence to these standard sanitation practices should be sufficient to reduce the risk of monkeypox virus transmission and no additional requirements (e.g., use of gloves, face masks) should be necessary when working with asymptomatic patients [110].

9 Conclusions

Infectious skin diseases are very common in sports with significant skin-to-skin contact. Mpox causes a systemic illness that precludes sports participation and may also cause complications that have deleterious effects on an athlete’s health. Mpox is not documented in athletes yet, but is likely to eventually reach athletes (especially in contact sports) and has the potential to cause outbreaks in sports settings. It is essential for sports organizations and their stakeholders to proactively address this issue in the hopes of minimizing mpox outbreaks. Mpox should be added to the differential list in athletes with skin lesions consistent with viral infections, and further evaluations, including a laboratory diagnosis, should be conducted on patients who can be classified with “suspected” or “probable” mpox. It is important for organizations to take appropriate measures to reduce the risk of mpox transmission in sports settings, including developing/following sports participation protocols for athletes with mpox exposure or diagnosis. These should be revisited and updated as more information regarding mpox becomes available.