TUBERCULOSIS IN SEA LIONS AND FUR SEALS FROM THE SOUTH-WESTERN ATLANTIC COAST

Diverse pathological conditions causing the strandings and/or deaths o f several species of sea lions and seals on the northern coast of the province of Buenos Aires are being studied. Tuberculosis was diagnosed in six cases of strandings, involving two otariid seal species (one O taria flavescens and five Arctocephalus australis), between March 1989 and December 1992. Necropsies were performed on all six cases. Granul omatous lesions were observed in the prescapular and hepatic lymph nod es. Lesions were also seen in the lungs, pleura, liver spleen and peri toneum. Bacteriological isolation was attempted from all the samples. The isolates were identified as belonging to the Mycobacterium tubercu losis complex. Some showed characteristics consistent with M. bovis, w hereas others demonstrated properties of M. tuberculosis. Genomic deox yribonucleic acid (DNA) from these strains was analysed by restriction fragment length polymorphism (RFLP), using IS6110, a genetic marker f ound only in the Mycobacterium tuberculosis complex. Using the IS6110 probe, similar fingerprints were obtained, suggesting a common source of infection. However the pattern of DNA differed from DNA patterns of M. bovis isolated from humans and cattle in Argentina, which generall y contain a unique 1.9 kbp band. These results suggest that mycobacter ia isolated from wild seals form a different grouping inside the M. tu berculosis complex. This is the first time that tuberculosis has been detected in wild seals from the south-western Atlantic coast.