DAO prepress abstract  -  DOI: https://doi.org/10.3354/dao03200

Tetracapsuloides bryosalmonae persists in brown trout Salmo trutta for five years post-exposure

Hatem Soliman*, Gokhlesh Kumar, Mansour El-Matbouli

*Email: hatem.soliman@vetmeduni.ac.at

ABSTRACT: Tetracapsuloides bryosalmonae is a malacosporean parasite and the causative agent of proliferative kidney disease (PKD) that seriously impacts farmed and wild salmonids. The parasite’s life cycle includes an invertebrate host, the bryozoan Fredericella sultana, and a vertebrate host, salmonid fish. The persistence of T. bryosalmonae in brown trout (Salmo trutta) for up to 2 yr following exposure is well documented. Results from the present study confirmed that one brown trout that had recovered from PKD did not completely clear the parasite from their tissues and that T. bryosalmonae can persist in this brown trout for up to 5 yr post exposure. Furthermore, recovered infected brown trout can release viable T. bryosalmonae spores that are able to infect specific pathogen free F. sultana colonies. T. bryosalmonae DNA was detected by PCR in every organs and parasite stages were observed in the kidney, spleen and liver following immunohistochemistry. This finding indicates that T. bryosalmonae infected brown trout can act as asymptomatic carrier and release the parasite for several years after the initial infection, acting as a reservoir of infection and contributing to disseminating the parasite to new areas.