Occurrence of bovine TB in Iranian cattle herds of Khuzestan, a laboratory study on postmortem specimens from tuberculin-positive cows

Abstract Khuzestan is a southwestern province of Iran with proximity to the Persian Gulf and the international border with Iraq where harsh climate seriously affects this oil-rich region. In a search for causative agents of bovine tuberculosis (bTB), slaughterhouse specimens (lymph nodes) from 32 tuberculin-positive cows originating from 17 farms were cultured on Lowenstein–Jensen slopes. This was further extended with bacterial culture of postmortem material from 6 trapped feral mice straying on the same farm premises. Twenty-five bovine and 2 murine acid-fast isolates were consequently obtained with all of them confirmed as Mycobacterium tuberculosis (MTB) complex bacteria by IS6110-PCR experiment. Spoligotyping and RD4 typing of the 2 murine and some of the collected bovine isolates left no doubt that Mycobacterium bovis is the principle and possibly the single culprit in bTB in this region. It does not come as a surprise as previous exhaustive works have shown in the Iranian environment other members of MTB complex than M. bovis are very unlikely to have any role in the epidemiology of bTB.