G.P.69 Haycocknema perplexum: A rare cause of eosinophilic myositis in Australia

Abstract

<h2>Abstract</h2> <i>Haycocknema perplexum</i> is a new genus of nematode that was originally discovered in two Tasmanian cases of polymyositis in 1998. Dr. Dennett and Dr. Spratt identified and described these unique, small nematodes within the muscle fibres. Ten years later another three cases were identified in Queensland. The sixth case was identified in a man living in Tasmania with polymyositis who failed to respond to treatment and review of the biopsy identified a number of these small nematodes. This sixth case, was a Tasmanian man who presented with a three year history of weakness which started with difficulty running but progressed to generalised weakness affecting both proximal and distal muscles and dysphagia. There was a 12kg of weight loss and loss of muscle mass. A muscle biopsy showed an eosinophilic myositis and he was treated for six months with immunosuppression with high dose oral prednisolone and methotrexate 25mg orally weekly. He continued to deteriorate on immunosuppression with increasing weakness and CK 6000U/L. His muscle biopsy was reviewed and small parasitic organisms were present within the fibres on the original biopsy, and <i>Haycocknema perplexum</i> was suspected and confirmed by Dr. Spratt who originally identified the first cases. Immunosuppression was ceased and albendazole started at a dose of 400mg bd. He had a dramatic improvement within 4weeks of treatment with an increase in weight, muscle strength and muscle bulk and reduction in CK. This sixth case had in common with the two Tasmanian cases, exposure to native wildlife. The lifecycle of this unique nematode is unknown and to date has only been identified in humans. Although rare, it is an important and treatable cause of eosinophilic myositis and further cases are likely to be identified. In the Queensland cases there was less improvement and early treatment is likely to be beneficial.