title: Novel insights into transmission routes of Mycobacterium avium in pigs and possible implications for human health.
abstract: Mycobacterium avium infection is a severe condition in humans, whereas pigs are often subclinically infected. Pig carcasses represent a possible source of human infection. Faecal excretion of M. avium was recently demonstrated in experimentally infected pigs, along with detection of M. avium in apparently normal lymph nodes. The present study investigates faecal excretion in naturally infected herds and the presence of live mycobacteria in lymph nodes. Two pig herds (A and B), with a history of sporadically suspected M. avium infection were sampled. Herd B used peat, as opposed to Herd A. Samples from peat, sawdust, drinking water, faeces and lymph nodes were collected. Identification of mycobacteria was performed by 16S rDNA sequencing and PCR. Mycobacterium avium isolates were analysed by Multi-Locus Variable Number of Tandem repeat Analysis (MLVA). Mycobacterium avium subsp. hominissuis was detected in samples of faeces, peat and lymph nodes from Herd B, often with identical MLVA profiles. Additionally, other non-tuberculous mycobacteria (NTM) were found in the same material. The absence of macroscopic lymph node lesions in the presence of M. avium subsp. hominissuis was frequently demonstrated. In Herd A, only one NTM isolate, which proved not to be M. avium, was found. Faeces might facilitate transmission of M. avium subsp. hominissuis between pigs and maintain the infection pressure in herds. The low incidence of macroscopic lesions together with the massive presence of M. avium subsp. hominissuis in lymph nodes from pigs kept on peat raises questions related to animal husbandry, food safety and human health.
authors.forename: Angelika
authors.initials: A
authors.lastname: Agdestein
authors.forename: Ingrid
authors.initials: I
authors.lastname: Olsen
authors.forename: Anne
authors.initials: A
authors.lastname: Jørgensen
authors.forename: Berit
authors.initials: B
authors.lastname: Djønne
authors.affiliation: Norwegian Veterinary Institute, P,O, Box 750 Sentrum, N-0106 Oslo, Norway. tone.johansen@vetinst.no.
authors.forename: Tone B
authors.initials: TB
authors.lastname: Johansen
mesh_terms: D000818:Animals; D058345:Asymptomatic Infections / Q000453:epidemiology; D004783:Environmental Microbiology; D005243:Feces / Q000382:microbiology; D005260:Female; D006801:Humans; D008198:Lymph Nodes / Q000382:microbiology; D008969:Molecular Sequence Data; D009162:Mycobacterium avium / Q000235:genetics / Q000502:physiology*; D009664:Norway / Q000453:epidemiology; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000662:veterinary; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA / Q000662:veterinary; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology / Q000382:microbiology / Q000635:transmission*; D014376:Tuberculosis / Q000453:epidemiology / Q000382:microbiology / Q000635:transmission / Q000662:veterinary*
chemical_list: D012336:RNA, Ribosomal, 16S
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