Myxobolus cerebralis caused severe declines in rainbow trout populations across Colorado following its introduction in the 1980s. One promising approach for the recovery of Colorado's rainbow trout populations has been the production of rainbow trout that are genetically resistant to the parasite. We introduced one of these resistant crosses, known as the GR×CRR (cross between the German Rainbo...

A detailed microbiological and parasitological survey of salmonids and indigenous fish in the upper reaches of selected river systems in Natal was undertaken. Fish were collected from the rivers by electro-fishing, from dams by gill netting and from hatcheries along the rivers. A total of 678 fish from 26 different sites along 8 river systems were collected. No parasites could be detected on fi...

Oligochaetes, triactinomyxons (TAMs), and age-0 trout were sampled in the upper Cache la Poudre River, Colorado, to determine the distribution of Myxobolus cerebralis during 1997 and 1998. Densities of the intermediate host, the oligochaete Tubifex tubifex, were 3.5 orders of magnitude higher in the M. cerebralis-infected Poudre Rearing Unit (PRU) trout rearing ponds than at any of the river sa...

Myxozoa are microscopic obligate endoparasites with complex live cycles. Representatives are Myxobolus cerebralis, the causative agent of whirling disease in salmonids, and the enigmatic "orphan worm" Buddenbrockia plumatellae parasitizing in Bryozoa. Originally, Myxozoa were classified as protists, but later several metazoan characteristics were reported. However, their phylogenetic relationsh...

Empirical estimates of pathogen prevalence in samples of fish may underestimate true prevalence because available detection techniques are incapable of perfect detection. Trout of several species were collected from enzootic (Myxobolus cerebralis, causative agent in whirling disease) habitats, and individual fish were examined for presence of the parasite two or six times by one of four methods...

Host biodiversity can impact disease risk and influence the transmission of parasitic disease. Stream sediment-dwelling worms, Tubifex tubifex (Clitellata: Oligochaeta), are the definitive host of the parasite Myxobolus cerebralis (Myxozoa: Myxosporea), which causes whirling disease in salmonid fishes. Genetic diversity of T. tubifex is correlated with host susceptibility to M. cerebralis , and...

We exposed 9 wk old rainbow trout Oncorhynchus mykiss to ambient levels of Myxobolus cerebralis infectious stages at 4 sites of suspected differing infectivity in the Colorado River. Exposure was estimated by periodic filtration of river water at each exposure location. After a 32 d exposure, the fish were held in the Colorado River at a common site for over a year. Resulting infection was eval...