Rhinoceros' Rhinorrhea: Cause of an Outbreak of Infection Due to Airborne Mycobacterium bovis in Zookeepers

Abstract

Seven of 24 zookeepers exposed to a Southern white rhinoceros infected with Mycobacterium bovis were presumably infected via aerosols generated in the cleaning of the barn for the rhinoceros. All demonstrated conversion by the intermediate-strength purified-protein-derivative skin test, but none had clinical illness. In certain occupational settings like zoos and abattoirs, exposure to M. bovis may be an occupational hazard, and routine periodic tuberculin screening should be performed.

Tuberculosis

“…Humans are also susceptible to M bovis, and there are numerous instances of human infection resulting from contact with infected animals. [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.…”

“…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. Although M bovis infection may be detected in other species, most of those affected animals are considered to be spillover hosts that require external sources of infection to maintain disease in their populations.…”

“…32 Respiratory transmission has been detected in herding animals, such as domestic cattle, 16,32 feral water buffalo, 46 and African cape buffa-lo, 44 and in captive herds of various cervid species. [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.…”

“…10,14 Contact with infected animals is another source of M bovis infection for humans and is a recognized hazard for abattoir workers, veterinarians, and livestock handlers. [5][6][7]11,[15][16][17] Among such workers who developed the disease, aerosol transmission was considered the most likely route of infection, but there are many occasions on which infection had been spread via cuts and abrasions (eg, butcher' s wart). 16 Although many of the primary nonaerosol sources of M bovis infection in humans have been removed in industrialized countries, there has been an increase in the number of cases of pulmonary infection with M bovis, which may be due to several factors: the lung is the usual site of postprimary M bovis infection, regardless of the site of the primary lesion; cases of pulmonary M bovis infection may be the result of reactivation of previously quiescent (ie, nonclinical) primary lesions; and infection may be the result of human-tohuman aerosol transmission.…”

Mycobacterium tuberculosis in zoo and wildlife species

“…However, M. tuberculosis has affected other species of rhinoceros, as noted above, and could conceivably be spread in a similar way. The risk of exposure to M. tuberculosis can be considered higher in zoo settings than in most other work environments (9,65).…”