Naturally occurring tuberculosis caused byMycobacterium bovisin brushtail possums (Trichosurus vulpecula): III. Routes of infection and excretion

Abstract

Mycobacterium bovis was cultured from nine of 25 (36%) tracheal washings but not from any of 38 urine and 38 faecal samples from tuberculous possums cross-sectionally sampled from the wild. One of three tracheal washings, one of three urine samples and one of three faecal samples from terminally ill possums were culture-positive. The respiratory route is implicated as the major route of excretion of Mycobacterium bovis from naturally infected possums in horizontal transmission. Tuberculosis was observed in two young possums and was evidence of probable pseudo-vertical transmission via the respiratory route or ingestion of milk. Discharging fistulae were present in 22 of 71 (31%) cross-sectionally sampled tuberculous possums and were associated with relatively advanced disease. Although the frequent involvement of superficial lymphocentres in early stage disease could not be explained satisfactorily, the respiratory route was implicated as the main route of infection from indirect evidence.

Oral vaccination reduces the incidence of tuberculosis in free-living brushtail possums

“…B (2009) factors (Coleman & Caley 2000): males forage more widely and juvenile males are more likely to disperse than juvenile females. Both activities presumably expose males to a greater risk of infection when fighting and maintaining larger activity areas ( Jackson et al 1995). Males may also have greater susceptibility to Tb infection than females .…”

Accuracy of Three Diagnostic Tests for Determining Mycobacterium Bovis Infection Status in Live-Sampled Wild Meerkats (Suricata Suricatta)

“…A similarly low sensitivity of tracheal wash culture as a diagnostic tool for tuberculosis was reported in a study of possums, 25 in which only 36% (9/25) of tracheal washes collected from tuberculous animals cultured positive for M. bovis. Low sensitivity in the current study may be due to limited pulmonary excretion of mycobacteria from tuberculous meerkats.…”

Tuberculosis

“…[47][48][49] Transmission of M bovis via inhalation appears to be effective in wildlife species that are kept in confinement in zoos 7 and in free-ranging wildlife species that maintain social or familial groups in underground dens, such as European badgers in the United Kingdom 40 and brushtail possums in New Zealand. 38 Furthermore, respiratory transmission of M bovis has been detected in wildlife populations during periods when normal behaviors become altered (for whatever reason) and result in more frequent direct contact between animals, such as that which occurred among white-tailed deer in Michigan in association with winter feeding. 26,50 Although respiratory transmission is the most important route of infection in groups of animals that remain in close contact, indirect transmission via feed contamination is another important route.…”

“…[5][6][7]16,17,[34][35][36][37] Throughout the world, the most commonly recognized hosts for M bovis are domesticated bovids. However, in recent years, several wildlife reservoir hosts have been identified, including brushtail possums in New Zealand, 38,39 European badgers in the United Kingdom, 40,41 white-tailed deer in Michigan, 42,43 and Cape buffalo 44 and several antelope species in South Africa. 36 Other species, such as elephants 45 and rhinoceros, 7,17 have been identified as hosts for M bovis infection in captivity.…”