Monitoring of Transmission of Tuberculosis between Wild Boars and Cattle: Genotypical Analysis of Strains by Molecular Epidemiology Techniques

Abstract

An epidemiological survey for the monitoring of bovine tuberculosis transmission was carried out in western Liguria, a region in northern Italy. Fifteen Mycobacterium bovis strains were isolated from 63 wild boar samples (62 from mandibular lymph nodes and 1 from a liver specimen). Sixteen mediastinal lymph nodes of 16 head of cattle were collected, and 15 Mycobacterium bovis strains were subsequently cultured. All M. bovis strains isolated from cattle and wild boars were genotyped by spoligotyping and by restriction fragment length polymorphism (RFLP) analysis with the IS6110 and IS1081 probes. All M. bovis strains showed the typical spoligotype characterized by the absence of the 39 to 43 spacers in comparison with the number inM. tuberculosis. A total of nine different clusters were identified by spoligotyping. The largest cluster included 9 strains isolated from wild boars and 11 strains isolated from cattle, thus confirming the possibility of transmission between the two animal species. Fingerprinting by RFLP analysis with the IS6110probe showed an identical single-band pattern for 29 of 30 strains analyzed, and only 1 strain presented a five-band pattern. The use of IS1081 as a second probe was useful for differentiation ofM. bovis from M. bovis BCG but not for differentiation among M. bovis strains, which presented the same undifferentiated genomic profile. In relation to the epidemiological investigation, we hypothesized that the feeding in pastures contaminated by cattle discharges could represent the most probable route of transmission of M. bovis between the two animal species. In conclusion, our results confirmed the higher discriminatory power of spoligotyping in relation to that of RFLP analysis for the differentiation of M. bovis genomic profiles. Our data showed the presence of a common M. bovisgenotype in both cattle and wild boars, confirming the possible interspecies transmission of M. bovis.

Diseases at the livestock–wildlife interface: Status, challenges, and opportunities in the United States

“…However, M. bovis has been isolated from free-ranging swine (i.e. wild boar and feral swine) in at least 15 countries (Letts, 1964;Corner et al, 1981;Essey et al, 1981;O'Reilly and Daborn, 1995;Aranaz et al, 1996;Serraino et al, 1999;Palmer, 2007). New evidence from Mediterranean ecosystems supports the role of wild swine as maintenance hosts of bTB-sustaining infection and transmitting the pathogen to other species (Aranaz et al, 1996;Naranjo et al, 2008).…”

Genes differentially expressed in oropharyngeal tonsils and mandibular lymph nodes of tuberculous and nontuberculous European wild boars naturally exposed toMycobacterium bovis

“…Furthermore, practical treatment or preventive measures other than control of host density and aggregation currently do not exist for free-ranging wildlife. The presence of common M. bovis genotypes in both cattle and wild boars poses a threat of interspecies transmission of the pathogen (Serraino et al, 1999).…”

Genetic resistance to bovine tuberculosis in the Iberian wild boar

“…2003;Roper 2003;Griffin et al . 2005), and bTB cases have been reported repeatedly in wild and semidomestic ungulates elsewhere in the world, including the European wild boar ( Sus scrofa ) (Serraino et al . 1999;Bollo et al .…”