Background:
Several species of enteric protozoa are associated with diarrheal illnesses in humans. However there is limited information about the epidemiology and geographical distribution of enteric protozoa in Australia. This is the first study to incorporate spatial analysis to define the epidemiology of enteric protozoa in the Australasia Region.

Methods:
Laboratory and clinical records from four public hospitals in Sydney (NSW) for 910 patients, who tested positive for enteric protozoa over the period January 2007- December 2010, were identified, examined and analyzed. We selected 580 cases which had residence post code data available, enabling us to examine the geographic distribution of patients, and reviewed the clinical data of 252 patients to examine possible links between protozoa, demographic and clinical features.

Results:
Frequently detected protozoa were Blastocystis spp. (57%), Giardia intestinalis (27%), and Dientamoeba fragilis (12%). The age distribution was bimodal, with the prevalence of protozoa decreasing with age up to 24 years but increasing with age from 25 years onwards. The geographic provenance of the patients indicates that the majority of cases of Blastocystis (53.1%) are clustered in and around the Sydney City Business District (CBD). The age distribution of cases suggests that schools, homes for the elderly are foci of infection.

Conclusion:
These findings provide useful information for policy makers to design and tailor interventions to target high risk communities. Follow-up investigation into the risk factors for Giardiasis in regional/rural areas is needed.