Tuberculosis (TB) caused by Mycobacterium bovis and other members of the Mycobacterium tuberculosis complex (MTC) remains a persistent challenge at the livestock–wildlife–human interface. Although long-standing eradication programs have substantially reduced bovine TB in many regions, MTC continues to circulate in wildlife reservoirs and may spill over into domestic animals, including pigs. Under certain ecological conditions, pigs can function as spillover or bridge hosts within multi-host systems, thereby contributing to environmental persistence and transmission opportunities (Di Marco et al., 2012; Cano-Terriza et al., 2018). Evidence from Mediterranean ecosystems, including Spain and Italy, has demonstrated MTC infection in domestic and wild swine populations, highlighting their epidemiological relevance where livestock, wildlife, and shared environments overlap (Di Marco et al., 2012; Cano-Terriza et al., 2018; Muñoz-Mendoza et al., 2013; Iovane et al., 2020). In contrast, countries dominated by intensive indoor pig production systems typically report low prevalence, emphasizing the influence of production ecology and wildlife contact on exposure risk (Campbell et al., 2011; Pedersen et al., 2017; Sun et al., 2024).

In the Republic of Korea, bovine TB has remained endemic for more than a century, with recent outbreak continuing despite sustained national efforts. In parallel, MTC infections have been documented in suids (Ku et al., 2016; Seo et al., 2017). M. bovis isolated from a wild sow (Sus scrofa) in 2012, exhibited a genotype distinct from strains circulating in cattle and deer, suggesting an independent or previously unrecognized source of exposure (Ku et al., 2016). In the same year, M. tuberculosis infection was confirmed in a domesticated wild boar through PCR and immunohistochemistry (Seo et al., 2017). Although such reports are sporadic, they indicate that domestic pigs and wild boars in Korea may be exposed to MTC and could participate as bridge hosts at the livestock–wildlife interface – an issue central to One Health surveillance.

Beyond MTC, the Mycobacterium avium complex (MAC), comprising M. avium and M. intracellulare, presents additional challenges for veterinary and public health sectors. MAC organisms are widespread in the environment, and pigs are susceptible to infection, often developing granulomatous lesions in mesenteric lymph nodes detected at slaughter. Although infections are frequently subclinical, MAC is associated with carcass condemnation and economic loss and may carry zoonotic implications, particularly for immunocompromised individuals (Hulinova Stromerova and Faldyna, 2018). In Korea, the incidence of MAC pulmonary disease in humans has increased, and M. avium is now frequently isolated in clinical settings (Kwon et al., 2019). Despite these trends, MAC exposure in Korean swine remains poorly characterized, limiting understanding of potential environmental or cross-species exposure routes. Notably, MAC, especially M. avium subsp. hominissuis, has been frequently detected in slaughter pigs and linked to lymph node lesions, underscoring its relevance to herd health and the food chain (Gcebe et al., 2023).

International studies report wide variability in mycobacterial prevalence in domestic pigs and wild suids, reflecting differences in production systems, wildlife reservoirs, and diagnostic approaches. Higher prevalence has been reported in wildlife-rich ecosystems and in settings with outdoor husbandry or established maintenance hosts, whereas low prevalence is typically observed in intensive indoor systems. However, direct comparisons among studies are constrained by methodological heterogeneity, including differences in the use of serology, PCR, culture, lesion inspection, or skin testing.

Taken together, the persistence of bovine TB, the occurrence of MTC infections in suids, and the growing public health significance of NTM – including MAC – highlight the need for integrated surveillance across animal species. Yet, no nationwide serological survey of M. bovis or M. avium exposure in swine has been conducted in Korea. This knowledge gap hampers risk assessment at the livestock–wildlife–human interface.

This study therefore aimed to (i) provide the first nationwide estimates of apparent seroprevalence of M. bovis and M. avium in domestic sows and wild boars in Korea, (ii) evaluate province-level heterogeneity while avoiding inference about spatial clustering beyond the resolution of the data, and (iii) position Korean swine mycobacterial exposure within a global One Health context.

This study provides the first nationwide serological assessment of exposure to M. bovis and M. avium in domestic sows and wild boars in Korea. By collecting samples across nine administrative provinces and applying validated ELISA assays, we establish baseline data that contribute to understanding mycobacterial exposure at the livestock–wildlife interface and provide a reference point for future surveillance efforts.

The apparent seroprevalence of M. bovis observed in domestic sows (4.54%) exceeds levels reported from several regions characterized by intensive indoor or semi-intensive pig production systems, including southern Spain (Cano-Terriza et al., 2018). Similarly, the seroprevalence detected in wild boars (5.91%) was higher than estimates reported from Portugal (Santos et al., 2018), the United States (Pedersen et al., 2017), Iberian Atlantic Spain (Muñoz-Mendoza et al., 2013), and Slovenia (Pate et al., 2024). In contrast, the Korean estimates were lower than those reported from multi-host systems in Campania, Italy (Iovane et al., 2020), northern Spain (Varela-Castro et al., 2020), and Malaysia (Lekko et al., 2021), where wildlife–livestock interfaces are known to support sustained transmission. Substantially, higher seroprevalence has been documented in African ecosystems, where warthogs (Phacochoerus africanus) function as maintenance hosts, with reported values reaching 37.6%–40.0% in South Africa (Roos et al., 2018; Neiffer et al., 2021). Collectively, these comparisons suggest that Korea occupies an intermediate epidemiological position between intensive production systems with limited wildlife contact and ecosystems characterized by persistent wildlife reservoirs. Nevertheless, such comparisons should be interpreted cautiously, as reported prevalence is strongly influenced by host populations, ecological context, and diagnostic methodology.

When placed in a broader international context, detection frequencies for M. bovis in suids have generally been low but variable across regions. For example, individual seroprevalence in Gansu Province, China, was reported at 0.22% (Sun et al., 2024), whereas higher detection rates have been described in Mediterranean settings, including 3.4% of slaughtered pigs in Sicily, Italy (Di Marco et al., 2012), and 2.3% seroprevalence among Iberian pigs in southern Spain (Cano-Terriza et al., 2018). For the MAC, reported frequencies likewise vary, ranging from 2.4% in slaughtered pigs in Egypt (Mohamed et al., 2009) to 4.6% in wild boars from Spain’s Iberian Atlantic region (Muñoz-Mendoza et al., 2013) and 1.9% in wild boars from southern Spain (García-Jiménez et al., 2015). Relative to these reports, the apparent seroprevalence observed in Korean domestic sows and wild boars does not indicate unusually high exposure but is consistent with measurable, low-to-moderate exposure levels.

The seroprevalence profile observed in Korea likely reflects the predominance of intensive indoor pig production systems, which limit direct contact between domestic pigs and wildlife, combined with potential environmental exposure arising from other reservoirs. Bovine tuberculosis continues to be reported in Korean cattle herds (Animal and Plant Quarantine Agency, 2025; Yoo et al., 2025), and prior documentation of M. bovis infection in a wild sow (Ku et al., 2016) and M. tuberculosis detection in a wild boar (Seo et al., 2017) supports the plausibility of multi-host exposure pathways. However, serological data alone cannot identify sources of infection or infer transmission routes, and the present findings should therefore be interpreted as evidence of exposure rather than active transmission.

Exposure to M. avium was more common than exposure to M. bovis in both domestic sows and wild boars, with apparent seroprevalence reaching 10.10% and 7.71%, respectively. Direct quantitative comparisons with previous studies are constrained by methodological heterogeneity, as many investigations of MAC in pigs and wild suids rely on culture or molecular detection rather than serology. Nonetheless, international studies demonstrate considerable variability in MAC detection in slaughter pigs and wild boars (Muñoz-Mendoza et al., 2013; Mohamed et al., 2009; García-Jiménez et al., 2015). The veterinary and public health relevance of MAC infections has been increasingly recognized, given their association with carcass condemnation in pigs and the rising incidence of MAC pulmonary disease in humans, including in Korea (Hulinova Stromerova and Faldyna, 2018; Kwon et al., 2019).

In the present study, significant regional variation in M. avium exposure was observed only among domestic sows, with the highest apparent seroprevalence detected in the Gyeonggi region. Studies addressing MAC exposure in domestic pigs or wild boars in Korea and East Asia remain extremely limited, underscoring the lack of regional baseline data. This finding should be interpreted cautiously, as statistical significance was driven by a single province. Gyeonggi Province encompasses the highest density of large-scale swine operations and complex peri-urban interfaces, suggesting that environmental factors such as water systems, bedding materials, or bioaerosols may contribute to elevated exposure risk (Hulinova Stromerova and Faldyna, 2018; Kwon et al., 2019). In contrast, wild boars exhibited no significant regional variation in MAC seroprevalence, consistent with diffuse, low-level environmental exposure rather than localized exposure foci, as reported in European wildlife studies (Muñoz-Mendoza et al., 2013; Richomme et al., 2019; Ghielmetti et al., 2021).

The concurrent detection of antibodies to both MTC and MAC in domestic sows and wild boars highlights several One Health considerations. Environmental and indirect transmission pathways may be sufficient to sustain low-level endemic exposure even in the absence of widespread outdoor pig farming. Korea’s high baseline prevalence of human tuberculosis and the increasing incidence of MAC pulmonary disease may further contribute to shared peri-urban exposure environments (Kwon et al., 2019; Yoo et al., 2025). In addition, other wildlife or meso-mammalian species, including rodents and small carnivores, may participate in local transmission networks, analogous to the role of brushtail possums in New Zealand’s bovine tuberculosis system (Nugent et al., 2012; Nugent et al., 2015). Evidence of mycobacterial infections in Korean companion animals and wildlife—including multidrug-resistant M. bovis isolated from a dog (Cho et al., 2022), M. avium infections in birds (Lee et al., 2010), and disseminated MAC infection in a captive tiger (Cho et al., 2006)—further underscores the relevance of integrated, multi-species surveillance.

Several methodological considerations warrant acknowledgment. ELISA-based assays are well suited for large-scale screening and have been widely applied in livestock and wildlife surveillance (Santos et al., 2018; Richomme et al., 2019; Cardoso et al., 2024); however, they primarily reflect prior exposure rather than active infection and may under-detect early or low-antibody responses. Accordingly, the apparent seroprevalence reported here should be interpreted as indicative of exposure rather than infection status. Reliable estimation of true prevalence would require robust, species- and context-specific diagnostic performance parameters that are currently unavailable for ELISA-based assays in suids. Complementary diagnostic approaches, including PCR, bacterial culture, interferon-gamma release assays, and histopathology, would improve epidemiological resolution (Mohamed et al., 2009; Cardoso et al., 2024).

The absence of demographic information for wild boars, such as age and sex, precluded assessment of risk factors known to influence infection dynamics in other settings (Muwonge et al., 2010; Arega et al., 2013; Demissie et al., 2020; Sanou et al., 2021). Similarly, individual- or farm-level risk factor analyses were not possible due to limited metadata on herd characteristics and management practices. The lack of spatial analysis further restricted identification of potential geographic clusters or transmission hotspots. Future studies integrating structured metadata, environmental variables, and molecular typing approaches – including spoligotyping, variable-number tandem repeat analysis, or whole-genome sequencing – would be instrumental in clarifying transmission pathways across hosts, as demonstrated in European multi-host systems (Amato et al., 2017; Madeira et al., 2017; Orłowska et al., 2020; Ciaravino et al., 2021; Welz et al., 2023).

Although tuberculosis is designated as a “Contagious Animal Disease Type II” under Korean legislation (Yoo et al., 2025), pigs are not currently included in routine national surveillance programs. Given the long production lifespan of breeding sows and the expanding geographic distribution of wild boars in Korea (National Institute of Biological Resources, 2023), integrating serological monitoring of both populations into existing surveillance frameworks could strengthen early detection and risk assessment. Experience from European wildlife–livestock tuberculosis systems demonstrates the value of coordinated surveillance, ecological risk evaluation, and targeted control strategies (Santos et al., 2009; Cano-Manuel et al., 2014; Mentaberre et al., 2014; Gortázar et al., 2017). Expanded environmental sampling and molecular epidemiological investigations would further clarify transmission pathways across species and ecosystems.

In conclusion, domestic sows and wild boars in Korea exhibit measurable exposure to both MTC and MAC. The observed seroprevalence profile lies between that reported for intensive indoor production systems and that observed in outdoor or wildlife-rich ecosystems with established reservoir hosts (Di Marco et al., 2012; Cano-Terriza et al., 2018; Lekko et al., 2021; Roos et al., 2018; Neiffer et al., 2021; Santos et al., 2009; Maciel et al., 2018; Barandiaran et al., 2024). These findings support the importance of sustained One Health surveillance and integrated multi-species monitoring to better understand and mitigate mycobacterial exposure risk in Korea.