Natalie Davidson¹, Kym Lowry², Bijendrasinh Vikramsinh Parmar¹, Thomas Robertson³, Rita Gupta¹, Patrick Harris^{1, 2}, David Whiley² 

¹ Department of Microbiology, Pathology Queensland, ² University of Queensland Centre for Clinical Research, ³ Department of Anatomical Pathology, Pathology Queensland. 

Introduction: Haycocknema perplexum is a rare and emerging cause of parasitic myositis with all described cases associated with residence or travel to Australia. To date, reservoirs and risk factors for human infection are not clear, resulting in delayed diagnosis and treatment. Diagnosis remains challenging and is confirmed on muscle biopsy with histological examination. Molecular techniques are not widely available but have been previously suggested as an adjunctive tool for diagnosis. 

Methods: We developed a real-time PCR assay targeting both SSU and COX-1 genomic regions. A total of 22 samples were collated (both fresh frozen and FFPE), derived from 8 patients with histopathologically-confirmed H. perplexum infection. Samples for specificity testing were also collected. 

Results: The assay demonstrated 100% specificity. The sensitivity of fresh frozen samples was superior to FFPE samples. Overall sensitivity was 84% for COX-1 and 92% for SSU target. All but 1 sample was negative following treatment. 

Conclusions: This study demonstrates the utility of this assay for diagnosis of H.perplexum, particularly on fresh frozen tissue samples as well as a possible test of cure. As knowledge increases, the ability to evaluate less invasive diagnostic options may become possible resulting in earlier diagnosis for these patients. All authors have contributed to this research.