Human tuberculosis due to Mycobacterium bovis and M. caprae in Spain, 2004-2007

OBJECTIVE: To identify the characteristics associated with human tuberculosis (TB) caused by Mycobacterium bovis and M. caprae in Spain.DESIGN: Retrospective study covering all M. bovis and M. caprae isolates identified at the National Mycobacterial Reference Laboratory (NRL) from 2004 to 2007. We studied the microbiological and epidemiological characteristics of patients and performed a genetic analysis of isolates.RESULTS: The study covered 110 isolates (89 M. bovis and 21 M. caprae) that accounted for respectively 1.9% and 0.3% of the M. tuberculosis complex isolates available at the NRL. Data on risk of exposure to M. bovis or to M. caprae were available in 82 (74%) of the 110 cases, with 60 (73%) registering a probable or possible risk of exposure and 22 (27%) registering no risk. Probable exposure mainly included crop and livestock farmers, and possible exposure included patients born in countries with a high prevalence of bovine TB. Spoligotyping of strains yielded 36 different patterns, with SB0121, SB0134 and SB0157 being predominant.CONCLUSIONS: In Spain, cases of human TB due to M. bovis and M. caprae represent a small proportion of all TB cases, and for a high percentage of cases this is linked to occupational exposure and coming from countries endemic for bovine TB.