Comparison of Enteric Protozoa testing Algorithms in Four Hospitals in Sydney, Australia

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The prevalence of intestinal protozoan infections affecting Australians is relatively unknown, and estimates are often affected by the lack of routine testing and insensitive diagnostic techniques to detect them in clinical specimens. This multi-centre cross section study summarises the relative prevalence of enteric protozoa from laboratory databases, across four public hospitals in Sydney, and compares the outcome of testing algorithms used to detect enteric protozoa.

The study found that detection rates varied between hospitals, with an enteric protozoa identified in 8.8% (95%CI 7.6%-10.0%), 1.2% (95%CI 1.0%-1.4%), 6.9% (95%CI 6.4%-7.5%) and 1.3% (95%CI 1.1%-1.6%) of specimen at Hospitals A, B, C and D respectively. Higher prevalence of Giardia was found in the 0-5 age group compared with higher rates of Blastocystis being identified from Adults (>5 years old) at Hospitals A and B. Where microscopy alone was used, Hospital A detected significantly higher results for Blastocystis spp., (mean diff. 5.3%; z-score =19.542; P Enteric protozoa contribute to the burden from Gastrointestinal Illnesses in Australia, and should be routinely considered in the differential diagnosis of locally acquired gastrointestinal illnesses. This study has shown that microscopy results were comparable to enhanced testing with permanent staining methods for some protozoa. However, permamnent stained smears should remain the method of choice for the detection of difficult to diagnose protozoa such as D. fragilis.