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Infection & disease

Parasitic pneumonia in a koala (Phascolarctos cinereus) from Victoria, Australia

McColl, KA & Spratt, DM 1982, Journal of Wildlife Diseases, vol. 18, no. 4, pp. 511-512.

A very sick, mature male koala was presented to the Veterinary Research Institute, Victoria where examination showed only arthritis in the stifle joint. Microscopic analysis of lung tissue revealed a mild parasitic interstitial pneumonia. In the koala, a range of disease syndromes have been described, yet until now none have resulted from infiltration by parasitic helminths.

  Parasitic pneumonia was distinguished by nematodes in the bronchioles, with increasing numbers within the lung itself. Invasion of immune cells surrounding proximal airways and into alveolar walls was noted. Lymphoid nodules were enlarged and Langhan’s giant cells had formed as a result of inflammation around the respiratory bronchioles. The lung parenchyma (alveoli, alveolar ducts and respiratory ducts) was beginning to undergo necrosis and hypertrophy of smooth muscle in the walls of bronchioles had occurred. The only substantial inflammatory reactions arose in respiratory bronchioles and the parenchyma, where accumulations of material resembling degenerating larvae and nematode cuticle were present. This indicated that the host’s reaction resulted from dead larvae/worms, with inflammation developing from repeated expulsion of the foreign material. Pathogenesis of the disease remained unknown; respiratory complications were not observed in the live koala, thus signifying minimal clinical significance.

  The nematode lungworm, identified as Marsupostrongylus sp., is only the second helminth recorded from the koala. The worm is similar to the lungworm M. longilarvatus in the brush-tailed possum; however, as normal morphological variation in this species is unknown, the koala lungworm cannot be identified to species.


Summarised by Julian Radford-Smith


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