Important unusual infections in Australia: a critical care perspective.
To review a number of the important unusual infections in Australia that can lead to critical illness. Articles, reports and published reviews on Japanese encephalitis, murine typhus, Australian spotted fever, Australian bat lyssavirus, leptospirosis, Capnocytophaga canimorsus, Chromobacterium violaceum, Edwardsiella tarda and Vibriosis. Emphasis was placed on articles, reports and published reviews published between 1990-2001. Japanese encephalitis has recently emerged in Australia, with reported outbreaks in the Torres Strait and north Queensland. Murine typhus needs to be included in the differential diagnosis of a patient with fever, headache and rash, especially if there has been possible exposure to rats and/or their droppings. If the symptoms follow exposure to ticks, or following a known tick bite, then Australian spotted fever needs to be considered. Australian bat lyssavirus can cause a fatal rabies-like disease in humans exposed to infection by bites or scratches from bats. Leptospirosis should be suspected in any patient with an appropriate history of exposure (especially occupational) and a history of myalgia, arthralgia, fever, malaise and/or chest X-ray shadowing. Capnocytophaga should be specifically sought in any patient with fever and/or septicaemia following a dog bite, especially if immunocompromised. Along with melioidosis, Chromobacteriosis should be considered in the differential diagnosis of a rapidly progressing septic illness with skin lesions and/or multiple visceral abscesses in a patient exposed to soil or muddy water. Edwardsiella ought to be considered as the causative agent of a soft tissue infection, septic arthritis or septicaemia in a recreational fisher or swimmer, especially if following a marine puncture wound. If the exposure is related to salty or brackish water, then Vibriosis needs to be considered. Vibriosis should also be suspected in a patient with septicaemia and a history of recent ingestion of raw or under-cooked seafood, especially oysters. Critical care physicians need to remain alert to unusual infectious agents as many can lead to significant morbidity and are associated with a high mortality rate.