Cinzia Marianelli ^1,2* Ivo Pavlik ³ Giovanni Ghielmetti ⁴

• ¹ National Institute of Health (ISS), Rome, Italy
• ² Department of Food Safety, Nutrition and Veterinary Public Health, National Institute of Health (ISS), Rome, Lazio, Italy
• ³ Department of Regional Development, Faculty of Regional Development and International Studies, Mendel University in Brno, Brno, Olomouc, Czechia
• ⁴ Sections of Veterinary Bacteriology and Avian diseases, Institute for Food Safety and Hygiene, University of Zurich, Zurich, Switzerland

Diseases caused by nontuberculous mycobacteria (NTM) represent a significant global public health concern. At present, NTM are defined as a group of environmental saprophytic organisms, comprising over 190 distinct species (1). Numerous NTM are opportunistic pathogens that can infect both animals and humans, resulting in a range of serious illnesses (2). Several studies have suggested that members of the Mycobacterium avium complex (MAC) are the most common NTM species identified in human infections and in particular in NTM lung disease (3). To date, MAC comprises twelve species, the most clinically relevant being M. avium, M. intracellulare, and M. chimaera (4).Mycobacterium avium is currently divided into four subspecies including avium (MAA), silvaticum (MAS), hominissuis (MAH), and paratuberculosis (MAP) based on virulence for animals and humans and other phenotypic peculiarities and specific genetic markers (4). MAH is the most clinically relevant to humans, often causing chronic pulmonary diseases and lymphadenitis in children and to pigs causing lymphadenitis in mesenteric and head (esp. submandibular) lymph nodes.MAP causes Johne's disease (paratuberculosis, PTB), a chronic granulomatous enteritis in ruminants.MAA and MAS have mostly been isolated from birds with tuberculosis-like disease.The incidence of NTM diseases has been rising, and there is currently no established method of eliminating/eradicating the sources of infections from the environment and/or hosts (5)(6)(7).Furthermore, vaccines have yet to be developed. This research topic, entitled "Nontuberculous mycobacterial infections in animals and humans: pathogenesis, diagnosis, prevention, treatment, and epidemiology", presents a collection of 12 studies that explore various aspects of NTM infections.Several studies address the efficacy of diagnostic tools for NTM diseases and possible interference with current ante mortem tuberculosis detection methods, others describe the occurrence of NTM in domestic and wild animals and the genetic diversity of NTM isolates from a wild population. Finally, a human case of NTM infection is also described. It reveals a high overall apparent prevalence of PTB at herd-level in sheep and goat farms, and reports animal-level prevalence data for both small ruminants. The study also indicates that the prevalence of PTB varies significantly between breeds of both sheep and goats.While the majority of contributions to this topic focus on NTM infections in both domestic and wild animals, the study conducted by Sun et al. -which describes a rare human case of lymphadenitis caused by M. chimaera -underscores the fact that NTM infections represent a significant public health concern for humans as well.Overall, these studies highlight the critical need for ongoing research and the development of comprehensive intervention strategies aimed at elucidating the mechanisms underlying NTM infections. These efforts are crucial for improving public health outcomes, enhancing veterinary management practices, and promoting effective wildlife conservation efforts, all within the context of a One Health Medicine and One Health approach.