Objectives To compare genotypes of Mycobacterium bovis strains from humans in Southern California with genotypes of M. bovis strains in cattle in Mexico and the USA to explore the possible origins of human infections. Methods We conducted a descriptive analysis of M. bovis genotypes from a binational population of humans and cattle using spacer oligonucleotide typing (spoligotyping). Results One hundred six human M. bovis spoligotypes were compared to spoligotypes from 496 Mexican cattle and 219 US cattle. Twelve spoligotype patterns were identified among human cases and 126 spoligotype patterns were detected in cattle. Over 91% (97/106) of the human M. bovis isolates had spoligotypes that were identical to those found in Mexican cattle. Four human cases had spoligotypes that matched both cattle born in Mexico and in the USA. Nine human cases had spoligotypes that did not match cattle born in Mexico or the USA. Conclusions Our data indicate that the population of M. bovis strains causing human TB disease in Southern California is closely related to the M. bovis strain population found in Mexican cattle and supports existing epidemiological evidence that human M. bovis disease in San Diego likely originated from Mexican cattle.

Background: Infectious pancreatic necrosis virus (IPNV) is a birnavirus that causes a lethal disease in both hatchery-reared juvenile salmonids and other non-salmonid fishes. IPNV has been classified into seven genogroups based on the analysis of the VP2/NS junction region of the viral A RNA segment. Methods: Ten organisms from two trout-rearing farms were used for viral isolation in RTG-2 cells. Cells were inoculated with samples from spleen, kidneys and pyloric caeca. The viral isolate was initially identified by electron microscopy, and confirmed by a commercial ELISA, RT-PCR and sequencing. A phylogenetic tree was constructed based on the deduced amino acids sequence of VP2. Results: An IPNV genogroup 1, labeled as EdoMex07, was isolated from a pool of renal tissues of five asymptomatic trout. The amino acid sequence analysis of VP2 showed that this IPNV presented the putative VP2 residue (221) already described in asymptomatic trout carriers. Conclusions: The EdoMex07 IPNV isolate belongs to genogroup 1, and has a VP2 phenotype which has been suggested to be involved in the establishment of the carrier state. This EdoMex07 IPNV is currently used as the standard positive control for detection of IPNV in rainbow trout farms in Mexico.