Mycobacteria fecal shedding in wild boars (Sus scrofa), South-eastern France

Abstract

11The recent recrudescence of tuberculosis in cattle has implicated wild boar as a 12 reservoir and vector of this disease, which led to the investigation of fecal shedding of 13 the causative Mycobacterium bovis. In the Provence region of France, wild boars are 14 very abundant, and the current study was carried out to assess the presence of 15 tuberculous and nontuberculous mycobacteria in feces of wild boar population. W e 16 developed an original protocol allowing the fast isolation of mycobacteria by 17 combining a 1%-chlorhexidine decontamination of fecal matter with culture on MOD9 18 medium. Colonies were identified by matrix-assisted laser desorption/ionization time-19 of-flight mass spectrometry, combined with DNA sequencing. This protocol yielded 20 no tuberculous mycobacteria among ninety-nine wild boar fecal samples collected in 21 the Provence region. However, non-tuberculous mycobacteria were isolated from five 22 samples (5.05%), including Mycobacterium peregrinum, Mycobacterium vaccae and 23 Mycobacterium setense, the last species being previously unreported in the wild 24 boar; in addition to two positive samples for Nocardia spp. In conclusion, wild boars 25 in southeastern France are not shedding tuberculosis agents, but they could 26 constitute a reservoir of human non-tuberculous mycobacteriosis in selected 27 populations directly exposed to wild boars.28 29 Bovine tuberculosis is a zoonosis due to Mycobacterium bovis (M. bovis) affecting 30 both livestock and wild mammals 1 . Bovine tuberculosis is a contagious infection of 31 significant health and economic importance and eradication programs have been 32 implemented in a number of developed countries 1,2 . These programs yielded a 33 remarkable reduction of the incidence of the disease 1,3 . 34 However, the wide distribution of M. bovis in wildlife is a major obstacle to the 35 eradication of tuberculosis in cattle 2,3 . In numerous countries, bovine tuberculosis is 36 maintained by multi-host systems involving cattle and wild mammals 2-4 . While the 37 role of the red deer (Cervus elaphus) remains controversial 3 , the European badger 38 (Meles meles) in Great Britain and Ireland and the wild boar (Sus scrofa) in the 39 Iberian Peninsula are acknowledged reservoirs for M. bovis 3,5 . The later species is 40 also recognized as a host for other Mycobacterium tuberculosis complex, including 41 Mycobacterium microti 6 and Mycobacterium caprae 7 . In addition, non-tuberculous 42 mycobacteria that are widely distributed in the environment are not uncommon in wild 43 boars, where they were isolated from lymph nodes 8 and feces 9,10 . These non-44 tuberculous mycobacteria have been identified as emerging human pathogens, 45 especially in immunocompromised patients 11,12 . 46 Accordingly, naturally infected wild boars excrete M. bovis mycobacteria by oro-47 nasal and digestive routes, with inocula above 10 3 colony-forming units (CFU)/g 13 . 48 Furthermore, it has been shown that M. bovis can persist in soil for several months 14 . 49 Interaction...