Salmonella Mississippi infections in Tasmania: the role of native Australian animals and untreated drinking water

Abstract

Salmonella Mississippi infections are very common in Australia's island state - Tasmania - with an annual rate of 17 cases/100000 population. A case-control study conducted during 2001-2002 found single variable associations with indirect exposure to many native animal species, untreated drinking water, travelling within the state, hand-mouth behaviours and contact with pet faeces. No associations were detected with farm animal or pet species or with any food. Indirect contact with native birds, untreated drinking water and travel within the state remained significant predictors of infection in the final model with population attributable fractions of 0.57 and 0.54 for native animals and untreated drinking water respectively. In Tasmania, Australian wildlife species are the likely reservoir for S. Mississippi, contaminating land and water environments. To decrease infection rates requires treatment of water supplies, particularly private rainwater collection systems and advising people to wash their hands after being outdoors and prior to eating.

Fig. 1

Human infections with S. Mississippi in Tasmania and other Australian States and Territories, 1990–2002 (Source: National Enteric Pathogen Surveillance Scheme, Microbiological Diagnostic Unit, University of Melbourne, Australia, 22 April 2005). □, Tasmania; ■, other Australian States and Territories.

Fig. 2

Possible transmission pathways for S. Mississippi infection in Tasmania, Australia.