Occurrence
M.bovis has a worldwide distribution except for a few countries
(e.g. Australia) and transmission to humans is usually via ingestion of
unpasteurised milk or dairy products, direct contact, and sometimes by aerosol
droplets or contact with infected sputum, urine or faeces
Species that can be infected include humans, cattle, deer, elk, goats, pigs,
domestic cats, llamas, foxes, coyotes, mustelids, badgers, possums, raccoons and
rodents. Some species (e.g. sheep and horses) are rarely infected. In many
countries wild mammals act as a reservoir for infection (e.g. opossums in New
Zealand and badgers in the UK) which has prompted control measures to control
their numbers
There is one report in the literature of infection in a household involving
human and canine patients with clinical signs and a latent human carrier (Shrikrishna
et al 2009)
Infected animals may be asymptomatic, or develop a chronic disease that
usually involves the lungs, lymph nodes and other organs showing signs
including fever, weight loss or respiratory signs such as coughing. Other
signs may gastrointestinal and cattle may develop mastitis.