Extraction of Whirling Disease Myxospores From Sediments Using the Plankton Centrifuge and Sodium Hexametaphosphate

Abstract

Mixobolus cerebralis, the causative agent of whirling disease in salmonids, has two transmission stages: the myxospore (released by salmonids) and the triactinomyxon (released by an aquatic tubificid worm, Tubifex tubifex). Myxospores are released into sediments after fish infected with M. cerebralis die and their carcasses decompose. The purpose or this study was to determine if it was possible to extract and enumerate M. cerebralis myxospores that were experimentally added to autoclaved sand and benthic sediments using a plankton centrifuge alone or in conjunction with sodium hexametaphosphate. The plankton centrifuge is commonly used to extract myxospores from salmonid skeletal elements and the technique involves filtration and sedimentation of myxospores. Sodium hexametaphosphate is a non-sudsing detergent that decreases oil aggregation making filtration more efficient. When the plankton centrifuge technique was used alone, we were only able to extract an average of 8 percent of myxospores inoculated into sediments. However, we were able to extract between 50-70 percent of M. cerebralis myxospores when sodium hexametaphosphate and the plankton centrifuge were used together. This technique could further enhance understanding of the ecology of the parasite and its association with T. tubifex.