The prevalence and impact of proliferative kidney disease (PKD) and
myxosporidiosis has been investigated in wild fish stocks in the UK, over 1,500 fish
representing 17 species being examined. PKD was recorded in brown trout, grayling
and pike, the causative agent, the PKX cell, being identified with the aid of light and
electron microscopy. A further 27 myxosporean species were also noted, with
Myxobolus cotti (syn. M. jiroveci), in the brain of bullheads Cottus gobio being
recorded for the first time. Studies on the structure and development of Myxidium
lieberkuehni in pike revealed several previously undescribed features.
Comparative morphological studies were undertaken to assess affinities of PKX
with known myxosporean species. Results indicated similarities with early
presporogonic stages of several myxosporean species, especially those belonging to the
genus Sphaerospora. The apparent rarity of spore formation associated with PKX
infections in the hosts examined focussed attention on species of Sphaerospora as
possible sources of infection to salmonids. Studies concentrated on the possible
involvement of the 3-spined stickleback, Gasterosteus aculeatus and its renal parasite,
Sphaerospora elegans, in PKD transmission. A re-description of this parasite (recently
elevated to "type species" for the genus), was prepared.
Laboratory experiments using rainbow trout PKX cells successfully transmitted
the infection to rainbow trout, brown trout, brook trout and grayling; however
sticklebacks challenged with PKX cells did not appear to become infected. Rainbow
trout challenged with S. elegans spores and presporogonic stages showed no evidence
of sphaerosporosis or PKD. Experiments designed to investigate the possible role of
tubificid worms in PKD transmission provided inconclusive results. Field studies
provided data on the pathogenesis of PKD in grayling and showed this species to be
highly susceptible to the disease.
Date of Award | 1993 |
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Original language | English |
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Awarding Institution | |
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INTER-RELATIONSHIPS OF MYXOSPOREANS, INCLUDING PKX WITH CERTAIN FRESHWATER FISH
FEIST, S. W. (Author). 1993
Student thesis: PhD