Occupational Risk Management in the Context of Emerging Infections

MPOX OVERVIEW AND OUTBREAK CONTEXT Mpox, formerly known as monkeypox, is a zoonotic disease caused by the monkeypox virus (MPXV), related to smallpox as they both belong to the Orthopoxvirus genus. It was first identified in 1958 during outbreaks in research animal colonies, and the first human case was detected in 1970 in the Democratic Republic of the Congo (DRC). MPXV has two main clades: Clade I, with subclades Ia and Ib, and Clade II, which includes subtypes IIa and IIb.1 Historically, Clade I has been associated with more severe symptoms and higher mortality rates than Clade II.1,2 The virus spreads through close contact with infected individuals, contaminated materials, or animals. Zoonotic transmission occurs when humans come into contact with infected animals, such as rodents or nonhuman primates, which seem to serve as natural reservoirs for the virus. The virus can also be transmitted during pregnancy, at birth, or through sexual contact. Considering the clade Ib, gay, bisexual, and men who have sex with men are identified as a higher-risk group. Mpox has a mortality rate ranging from 1% to 11%, depending on the clade and patient demographics.3 Both clades have caused outbreaks in rural Africa. At the same time, Clade IIb was responsible for the 2022–2023 global outbreak, which resulted in over 100,000 cases across 122 countries, including 115 where Mpox had not previously been reported.4 This outbreak was marked by new epidemiological patterns and constituted an extraordinary event due to the risk of international spread that needed for global coordination. In response, the World Health Organization (WHO) declared Mpox a global health emergency that remained in effect from July 2022 to May 2023.4 In 2023, a new outbreak driven by Clade Ib, predominately spreading in sexual networks, emerged in the eastern DRC, spreading to neighboring countries such as Burundi, Kenya, Rwanda, and Uganda. Simultaneously, Clade Ia, mostly affecting children, continued to expand in the northern, central, and western regions of the DRC, contributing to the complex epidemiological landscape. By August 2024, over 17,000 suspected cases and 2863 confirmed cases had been reported, prompting the Africa CDC to declare a health emergency. This was followed by a public health emergency declaration from the WHO. As of December 2024, the DRC and neighboring countries in Central and Eastern Africa have reported more than 50,000 suspected Mpox cases and 1000 associated deaths.4 The outbreak remains particularly severe in the eastern DRC and Burundi.5,6 Meanwhile, the international spread of Clade Ib was documented, with Sweden reporting the first European Union (EU) case in August 2024, followed by the UK's first detection on October 30, 2024, in a traveler returning from an endemic region. Actually, 11,911 cases of Clade 1 are reported worldwide, with cases reported outside Africa also in the US, Germany, India, and Thailand5,6 Unlike the 2022 outbreak, the Mpox surge in mid-20237 is primarily linked to heterosexual contact and is characterized by more severe symptoms, with a mortality rate of around 5% in adults and 10% in children and immunocompromised individuals. However, the reported severity of Mpox Clade I compared to Clade II may also be influenced by population differences, particularly age. Additionally, factors such as HIV status, regional healthcare quality, and publication biases also contribute to variations in severity and outcomes between regions.8 Since January 1, 2022, cases of Mpox have been reported to WHO from 24 Member States across Africa. As of 22 December 2024, a total of 16,495 laboratory-confirmed cases, including 83 deaths, had been reported to WHO. A significant number of suspected cases clinically compatible with Mpox remain untested due to limited diagnostic capacity in some African countries and thus never get confirmed.9 The evolving dynamics of the emerging Mpox outbreak underscore the urgent need for comprehensive risk management strategies. A critical concern within this framework is the occupational risk faced by workers with heightened exposure to the MPXV. Although sexual transmission remains the predominant mode of spread, occupational exposure poses a significant risk, particularly for individuals engaged in activities that facilitate interaction with infected animals or humans, such as HCWs.10 Effective management of Mpox and similar infectious threats requires prioritizing high-risk occupational groups and implementing adaptive risk mitigation strategies that respond to the virus's evolving nature. This approach is essential to containing further outbreaks, reducing global transmission risks, and preventing future pandemics. RISK FACTORS AND ROUTES OF TRANSMISSION IN OCCUPATIONAL SETTINGS Multiple risk factors for Mpox range from contact with wildlife through lack of vaccination and immunosuppression and socioeconomic factors. Hunting, trading, and consuming wild animals are strong risk factors for Mpox infection, whereas being unvaccinated for smallpox and being HIV positive are negative prognostic risk factors.11,12 Additionally, individuals in underserved communities with limited access to healthcare services or residing in overcrowded conditions face an increased risk of Mpox infection.13 Assessing the transmission risks of MPXV in workplaces requires a thorough understanding of its transmission routes, which include both animal-to-human and human-to-human pathways. The assessment of zoonotic transmission is particularly challenging, partly because, although certain small mammals, such as rope squirrels, pouched rats, and African dormice, along with some primates like chimpanzees, are susceptible to MPXV, the primary reservoir species of MPXV have yet to be identified. This uncertainty highlights the need for a multidisciplinary integrated approach to monitoring animal populations to prevent human outbreaks caused by zoonotic transmission.14 Human interaction with bushmeat moreover may play a significant role in Mpox transmission, with 16 documented spillover events linked to this interaction over the last decade (2014–2024).15 Additionally, settings like wildlife markets, zoos, and farms also pose high risks for spillover events due to close human-animal contact, making them critical points for proactive surveillance.15 As of November 30, 2024, the WHO reported 6.1% of Mpox confirmed cases with available data (1073 out of 17,688) involving individuals with a history of animal contact.16 Also, historical outbreaks indicate the occupational hazards associated with animal contact. The 2003 Mpox US outbreak, resulting from African rodents housed with prairie dogs, infected 12 veterinarians, two pet store employees, and two pet distributors, likely due to inconsistent personal protective equipment (PPE) use. This incident highlights that workers in occupations involving direct contact with animals could be particularly susceptible to zoonotic MPXV exposure.17,18 Considering this evidence, a One Health approach, which integrates human, animal, and environmental health perspectives, is essential for effective Mpox occupational risk management. Collaboration among veterinary services, wildlife conservation, and public health organizations can help establish an early warning system, supporting Mpox containment and reducing occupational risks for vulnerable groups. Surveillance should focus on high-risk regions where zoonotic transmission is more likely, ensuring targeted and efficient monitoring.19 Human-to-human transmission of MPXV, especially through direct contact with skin lesions, also poses risks in occupational settings, as observed during the 2022 outbreak.20 In particular, the relationship between viral load and transmission risk is critical for understanding Mpox infectivity patterns. Mpox viral load varies significantly across different anatomical sites, with the highest viral concentrations detected in skin lesions, anorectal swabs, and saliva samples. These findings strongly support the hypothesis that direct contact with infected lesions and mucosal surfaces plays the most significant role in Mpox transmission. Specifically, the median cycle threshold (Ct) values, which are inversely correlated with viral load, were lowest in skin (Ct 21.7) and anorectal (Ct 22.3) samples, highlighting these as the primary transmission sources. Additionally, viral culture studies confirm that infectious virus can be recovered from anorectal samples for up to 19 days and from saliva for up to 14 days, further reinforcing the high transmission potential of these sites.21 Additionally, MPXV DNA has been detected on surfaces, raising concerns about viral persistence and possible fomite transmission, although the exact risk remains uncertain. Moreover, exposure pathways like aerosol transmission, although not yet well defined, appear to be plausible. In contrast, pharyngeal and nasopharyngeal samples exhibit higher Ct values, indicating lower viral loads and reduced infectivity potential. Although viable virus has been detected in saliva early in infection, the limited detection of airborne Mpox particles in environmental studies suggests that respiratory transmission is not a dominant route. This is consistent with epidemiological evidence showing that most Mpox infections occur through close skin-to-skin or mucosal contact. Evidence from clinical and experimental studies reveals that high MPXV DNA loads in respiratory fluids, particularly saliva, can facilitate the generation of aerosolized viral particles. For instance, saliva samples from symptomatic patients exhibited viral loads as high as 1 × 108 copies per milliliter, with infectious virus frequently detected. Theoretical models based on aerosol physics indicate that respiratory particles carrying MPXV can range in size and, under specific environmental conditions, such as low humidity and high airflow, can transition into airborne aerosols capable of spreading the virus. Environmental sampling further substantiates this risk, with MPXV genomes and infectious particles detected in air samples taken from hospital settings, including at distances exceeding 1.5 m from infected individuals.22 Additionally, the virus demonstrated viability in airborne particles for up to 90 hours under controlled conditions.22 This route of transmission could be particularly relevant in high-density workplaces, like care facilities, or correctional settings, where airborne contact is frequent.23 A 2022 case report from the US focused on the possible occupational risks in correctional facilities: a 63-year-old officer contracted Mpox despite no direct contact with infected individuals, their environments, or other known exposure routes, strongly suggesting aerosol transmission.24 Correctional settings present unique risks for Mpox transmission due to overcrowding, poor healthcare access, limited awareness, and higher-risk behaviors such as sharing personal items or having multiple sexual partners. These factors, coupled with the high turnover in remand facilities, exacerbate vulnerability. Additionally, prisons often house transgender individuals and others with higher-risk behaviors, further heightening the risk.25 Moreover, pieces of evidence suggest that MPVX can adapt to new transmission networks through occupational exposures involving close contact. A recent study focuses on the transmission of MPXV specifically within a tattoo and piercing parlor in Cadiz, Spain, during the Mpox outbreak in 2022. Over 2 weeks, 21 out of 58 customers (36%) contracted the virus through piercing or tattooing. None of the infected individuals had a history of high-risk sexual behavior, travel to endemic regions, or known contact with infected individuals, suggesting that the virus was transmitted through direct inoculation during procedures. This outbreak underscores the potential for Mpox to exploit occupational vulnerabilities, particularly in industries involving close physical interaction or procedures that breach the skin.26 HCWs remain the principal concern among the possible occupational infection considering that, as of November 30, 2024, the WHO reported 1401 Mpox cases among HCWs.16 During the 2022 Mpox outbreak, however, transmission to HCWs was relatively low in Western countries even with direct contact with patients. For example, in Colorado, 313 HCWs had direct skin contact with infected individuals, yet no major transmission occurred, suggesting that the risk is particularly higher in deserved regions.22 Moreover, HCWs remain at significant risk of exposure to MPXV via respiratory secretions, considering that the virus is detectable in the oropharynx before the onset of cutaneous manifestations. This transmission mode is not exclusive to Clade Ib but is a characteristic of MPXV infection broadly, as documented in multiple studies. Furthermore, percutaneous exposure, including injuries from needles or cuts, exacerbates the occupational hazards faced by HCWs managing Mpox cases.22 In African countries, healthcare settings seem to be mostly at risk due to poor infrastructure and lack of PPE. Guidelines for managing Mpox cases need to be implemented to increase awareness among HCWs about and symptoms of Mpox with case a high of in making the at and with during the and procedures. of suspected or confirmed cases and risk should also be Moreover, management in healthcare the risk of in the understanding of MPXV strategies for HCWs should the risk of transmission during the to hours the onset of cutaneous manifestations. This characterized by symptoms such as and often occurs of involving close interaction with the such as and could be associated with increased exposure risks, particularly during for early clinical is essential to occupational Although significant have been in understanding MPXV transmission, epidemiological and clinical research has focused on these with on occupational risks specific to RISK the of an emerging disease such as Mpox in occupational settings during the outbreak is due to the evolving of the virus's transmission, clinical and epidemiological patterns. Moreover, as with zoonotic Mpox may new about the respiratory route of transmission, the role of and clinical This uncertainty highlights the need for an and for risk assessment and management. 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