Mycobacterial infections in cattle and pigs caused by Mycobacterium avium complex members and atypical mycobacteria

Bovine tuberculosis was last detected in cattle and pigs in the Czech Republic in 1995. Since March, 31, 2004 (Commission Decision No. 2004/320/EC) the Czech Republic has been included amongst states free from bovine tuberculosis within the European Union. The purpose of the present study was to evaluate results of intravital and post-mortem diagnosis of mycobacterial infections in slaughtered cattle and pigs from 2000 to 2004. When bovine tuberculosis in cattle was investigated, a tuberculin skin test with bovine tuberculin was performed every year and a skin test with avian tuberculin was simultaneously conducted in the animals with a positive response. A total of 2 419 889 animals were examined with a positive response being found in 123 (0.005%) of them. After slaughter, bovine tuberculosis was not detected in any of these animals by gross and/or laboratory examinations. With avian tuberculin, 40 349 animals were tested and positive responses were detected in 43 (0.1%) of them; the incidence was similar in all the years monitored. Tuberculous lesions were detected in 209 (0.01%) of 1 967 211 slaughtered cattle. Mycobacteria were present in 40 (21.3%) of 188 animals examined by laboratory methods: 26 isolates of Mycobacterium avium subsp. avium (18 isolates of serotype 2 and 8 isolates not typeable), 11 isolates of M. a. hominissuis (1 isolate of serotype 8 and 10 isolates not typeable), and 3 isolates of atypical mycobacteria. Tuberculous lesions were detected in 49 312 (0.22%) of 22 312 580 slaughtered pigs by veterinary-meat inspection. During the 5-year-period monitored, the incidence of tuberculous lesions decreased from 0.37% in 2000 to 0.10% in 2004. The following mycobacteria were isolated from 757 (33.5%) of 2 261 animals whose organs were examined by culture: 203 isolates of M. a. avium (180 isolates of serotype 2, 3 isolates of serotype 2/8, and 20 isolates not typeable), 442 isolates of M. a. hominissuis (1 isolate of serotype 1, 262 isolates of serotype 8, 35 isolates of serotype 9, 1 isolates of mixed serotypes 8/9, and 143 isolates not typeable), and atypical mycobacteria (n = 112). In both animal species, M. avium complex members prevailed: M. a. avium was the most prevalent subspecies in cattle, M. a. hominissuis in pigs. The main sources of M. a. avium and M. a. hominissuis are free living birds and contaminated external and stable environments (i.e. drinking water, feeds, and feed supplements), respectively. During the entire period monitored, miliary or generalized tuberculosis was not detected in any of the animals. The decreased incidence of tuberculous lesions in pigs was particularly a result of preventive measures adopted to control the occurrence of atypical mycobacteria.