PKX, the myxosporean causing proliferative kidney disease (PKD), was transmitted to rainbow trout Oncorhynchus rnykiss following their exposure to filtered sedirnents and water from a recycled water system where PKD is enzootic. Suspended sedirnents (25 1) were passed sequentially through 500, 250, 100 and 50 pm screens. Infectivity was found with material trapped at 500 pm and in water passing the 50 pm screen. No infectivity was found with material trapped on the 250, 100 or 50 pm screens. In a second study, 180 1 of water was passed sequentially through a series of filters identical to those used in the sediment trial. No infectivity was trapped on any size filter (500 to 50 pm) but 10 of 20 trout exposed to water passing all filters were infected with PKX. The association of PKX infectivity with material 500 pm in the sediments and with a stage smaller than 50 pm in the water is consistent with the hypothesis that a second host residing in the sediments releases a smaller infective stage found in the water, as shown for other myxosporean/ actinosporean parasite life cycles. A small oligochaete (Stylaria lacustris) found on the 500 pm filter is under investigation as the possible secondlalternate host of the PKX rnyxosporean.
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Aquatic Science