Experimental transmission of two Myxobolus spp. developing bisporogeny via tubificid worms.

Spores of Myxobolus cotti El-Matbouli and Hoffmann 1987 and M. cerebralis Hofer 1903 (fresh or after 5 months in mud) are taken in by tubifex worms and develop in their gut epithelium cells into actinosporea of the genus Triactinomyxon. Triactinomyxon deriving from M. cotti differ distinctly from those derived from M. cerebralis in morphology and the number of sporozoites in the epispore. It could be shown that Triactinomyxon spores infect fish either via the water (bullhead, rainbow trout) or by feeding of infected tubifex (rainbow trout), developing into Myxobolus spores in central nervous tissue (bullhead) or cartilage (rainbow trout). Fresh or ripened spores of M. cotti and M. cerebralis were not infectious for bullheads or rainbow trout, respectively. The results of our experiments confirm the hypothesis that the life cycle of M. cotti and M. cerebralis includes an intermediate host and a metamorphosis into actinosporea of the genus Triactinomyxon.