Animal melioidosis in Australia

Abstract

Melioidosis was first diagnosed in Australia in sheep in 1949. While it has been considered endemic in tropical Australia, there have been animal outbreaks in southwest Western Australia and southern Queensland. Infection occurs in many species, with both latency and a wide range of clinical manifestations. Some species may develop melioidosis only if immunocompromised. Sheep and goats are particularly susceptible, resulting in the requirement for pasteurisation of tropical commercial goat's milk. Nine out of 43 (21%) goats had aortic lesions at autopsy and seven died from aortic aneurysm rupture. Transplacental transmission in goats has also been documented. Asymptomatic organ abscesses are common in pigs but bovine melioidosis is very rare. Camels moved north and an alpaca brought to Darwin have died from melioidosis. It also occurs in wildlife, including birds, crocodiles and kangaroos. Zoonotic transmission to humans is extremely unusual, but there are many similar epidemiological and clinical features of melioidosis in animals and humans. There have been three possible zoonotic cases in Australia. Molecular typing has found identical Burkholderia pseudomallei organisms from animals, humans and soil. The study of melioidosis in animals, especially the use of molecular genetic techniques for organism identification and typing, will continue to unravel aspects of the disease that remain unclear in humans.