Mycobacterioses

The Mycobacterium tuberculosis complex MTC is composed of several species of mycobacteria which are M. tuberculosis, the main cause of human tuberculosis, M. canetti, M. africanum, M. microti, M. pinnipedii, M. caprae, and M. bovis. Cattle are the principal host of M. bovis, but a large number of other ruminants and other mammals, particularly wildlife are infected. Human tuberculosis is a global problem of huge proportions. More than 95% of human tuberculosis cases occur in developing and transition countries, of which one third are in Africa but the proportion of cases caused by M. bovis is still not known. Today, bovine tuberculosis (BTB) is re-emerging and threatens the livestock industry in industrialized countries with wildlife reservoirs like the wild tailed deer (Odocoileus virginianus) in the USA or the badger (Meles meles) in the UK. Most developing countries lack the means and capacity for effective control of BTB. A better understanding of its epidemiology is required to identify novel, locally adapted options for control in a given context. BTB in Africa is emphasized here because of the special importance of multiple transmission interfaces between wildlife, livestock and humans.

In addition to obligatory pathogenic mycobacteria (esp. members of the MTC), potentially pathogenic mycobacteria (PPM) previously designated as ‘mycobacteria other than tubercle bacilli’ (MOTT) are increasingly important causes of mycobacterioses in humans and animals. Most of them are opportunistic in humans and occur mostly in immunocompromised patients. The mycobacteria that cause human disease are both the M. avium complex (MAC) members and other mycobacterial species MAC members have been detected in more than 95% of cases; this chapter will mainly focus on M. avium subsp. avium, M. a. hominissuis, and M. intracellulare.