Zoonotic aspects of Mycobacterium bovis and Mycobacterium avium-intracellulare complex (MAC)

Abstract

-Pathogens that are transmitted between the environment, wildlife, livestock and humans represent major challenges for the protection of human and domestic animal health, the economic sustainability of agriculture, and the conservation of wildlife. Among such pathogens, the genus Mycobacterium is well represented by M. bovis, the etiological agent of bovine tuberculosis, M. avium ssp. paratuberculosis (Map) the etiological agent of Johne disease, M. avium ssp. avium (Maa) and in a few common cases by other emergent environmental mycobacteria. Epidemiologic surveys performed in Europe, North America and New Zealand have demonstrated the existence and importance of environmental and wildlife reservoirs of mycobacterial infections that limit the attempts of disease control programmes. The aim of this review is to examine the zoonotic aspects of mycobacteria transmitted from the environment and wildlife. This work is focused on the species of two main groups of mycobacteria classified as important pathogens for humans and animals: first, M. bovis, the causative agent of bovine tuberculosis, which belongs to the M. tuberculosis complex and has a broad host range including wildlife, captive wildlife, domestic livestock, non-human primates and humans; the second group examined, is the M. avium-intracellulare complex (MAC) which includes M. avium ssp. avium causing major health problems in AIDS patients and M. avium ssp. paratuberculosis the etiological agent of Johne disease in cattle and identified in patients with Crohn disease. MAC agents, in addition to a broad host range, are environmental mycobacteria found in numerous biotopes including the soil, water, aerosols, protozoa, deep litter and fresh tropical vegetation. This review examines the possible reservoirs of these pathogens in the environment and in wildlife, their role as sources of infection in humans and animals and their health impact on humans. The possibilities of control and management programmes for these mycobacterial infections are examined with regards to the importance of their natural reservoirs.

A review of bovine tuberculosis at the wildlife–livestock–human interface in sub-Saharan Africa

“…2; adapted from [33,53,[77][78][79][80][81]) include the type of production system (intensive, dairy farms, use of upgraded B. taurus breeds), animal movements (herds importing animals, transhumance) and absence or inefficiency of bTB surveillance and control. Several studies have analysed bTB risks of transmission between livestock and humans [58,67,75,80,82], identifying husbandry practices (housing, mixing cattle herds with other small ruminants), food preferences (consumption of raw or soured milk) and overall health and hygienic conditions (HIV) as the main risk factors for humans (Fig. 2).…”

Molecular characterization and drug susceptibility profile of a Mycobacterium avium subspecies avium isolate from a dog with disseminated infection

“…The most common mode of transmission amongst dogs is environmental (Biet et al, 2005). MAC can invade the body through the skin, respiratory or gastrointestinal tracts and usually causes focal disease with skin, respiratory or gastrointestinal lesions.…”

“…Humans are commonly and continuously exposed to MAC organisms present in wildlife, domestic animals and natural biotopes (Biet et al, 2005), but only a very small percentage of human/mycobacteria interactions progress to an outright mycobacterial infection. Such progression is much more common in the immunocompromised, notably AIDS patients, in whom MAC organisms in general, and M. avium subsp.…”

A descriptive spatial analysis of bovine tuberculosis in intensively controlled cattle farms in New Zealand

“…Bovine tuberculosis (TB), caused by Mycobacterium bovis, is an infectious disease that causes economic, public health [4,27], and ecological concerns around the world [2,7,15]. The incidence of bovine TB in New Zealand has been reduced through a national test-andslaughter policy which has been compulsory for all dairy and beef herds since the 1960s [1,10].…”