A ciliate infection (Paranophrys sp.) in laboratory-held Dungeness crabs,Cancer magister

A ciliate infection ascribed to the genus Paranophrys was found in early adult Dungeness crabs, Cancer magister, held in laboratory bioassay facilities, and in outdoor flow-through tanks in Newport, Oregon. Infections proved lethal as ciliates multiplied to high densities in the blood and tissues causing degeneration and necrosis of musculature. All infected crabs had recent wounds through the exoskeleton which probably provided a portal of entry, and the elapsed time between infliction of a wound and gross symptoms of stress was estimated at 9 days although animals died as late as 26 days. The nature of Paranophrys infections in C. magister, i.e., as an opportunistic pathogen of cultured animals and/or a disease in wild populations of this crab is discussed.