The aquatic oligochaete Tubifex tubifex is an obligate host of Myxobolus cerebralis, the causative agent of salmonid whirling disease. Tubifex tubifex can become infected by ingesting myxospores of M. cerebralis that have been released into sediments upon death and decomposition of infected salmonids. Infected worms release triactinomyxons into the water column that then infect salmonids. How t...

Salmonid species vary substantially with respect to both susceptibility and pathology when challenged with Myxobolus cerebralis (O’Grodnick 1979). Even within a species, strain differences in susceptibility have been demonstrated (Densmore et al. 2001). Rainbow trout are generally accepted to be one of the most susceptible species to M. cerebralis infection, yet are one of the most popular spor...

The core of the theory of absolutely summing operators lie in the ideas of A. Grothendieck in the 1950s. Further work (after a decade) of A. Pietsch [21] and Lindenstrauss and Pe lczyński [11] clarified Grothendiecks insights and nowadays the ideal of absolutely summing operators is a central topic of investigation. A natural question is how to extend the concept of absolutely summing operators...

Single-round polymerase chain reaction (PCR) and pepsin-trypsin digest (PTD) methods were compared for the detection of Myxobolus cerebralis. Parallel tests were conducted on a total of 1743 free-ranging and 400 hatchery-reared salmonids. Concurrent results were found in 84.6% of the free-ranging fish samples, and 83.5% of the hatchery samples. PCR identified M. cerebralis more frequently than ...

of the wildlife resources and a producer of additional fish and game via hatcheries and habitat management. Sometimes these roles of commodity versus stewardship are at odds. Such is the case where the DWR stocks exotic species such as rainbow trout to provide recreational fishing while attempting to conserve populations of native species such as the cutthroat trout. Cutthroat are the only trou...

We are conducting studies on the impacts of parasites on Oregon coastal coho salmon (Oncorhynchus kistuch). An essential first step is documenting the geographic distribution of infections, which may be accomplished by using different methods for parasite detection. Thus, the objectives of the current study were to (1) identify parasite species infecting these stocks of coho salmon and document...

A myxosporean infecting the gill filaments of the freshwater teleost Semaprochilodus insignis collected in the Trombetas River (Central Amazonian Region, Brazil) is described using light and electron microscopy. The spores were ovoid in frontal view with round extremities and measured 15.4 ± 0.6 μm in total length, 12.4 ± 0.5 μm wide and 8.1 ± 0.7 μm thick; the spore valves (up to 0.4 μm) were ...

a systematic parasitological examination was carried out on 266 freshwater fish speci-mens, belonging to 11 species, from northwest of iran during the period from summer 2001 to summer 2002. twelve parasite species including diplostomum spathaceum, al-locreadium isoporum, ligula intestinalis, digrama sp., caryophylleus laticeps, rhabdocona hellichi, eustrongylides excisus, argulus foliaceus, la...