Bf. Ardelli et al., BROOK CHARR, SALVELINUS-FONTINALIS (MITCHILL), AND CRYPTOBIOSIS - A POTENTIAL SALMONID RESERVOIR HOST FOR CRYPTOBIA-SALMOSITICA KATZ, 1951, Journal of fish diseases, 17(6), 1994, pp. 567-577
Laboratory-raised Cryptobia-susceptible brook charr, Salvelinus fontin
alis (Mitchill), and rainbow trout, Oncorhynchus mykiss (Walbaum), wer
e vaccinated intraperitoneally with a live Cryptobia salmositica vacci
ne (250000 parasites per fish), and 4 weeks later were challenged with
the pathogen (250000 parasites per fish). Unvaccinated and infected b
rook charr had high parasitaemias but no clinical signs of disease, wh
ile unvaccinated and infected rainbow trout had anaemia and general oe
dema. Vaccinated and challenged fish had very low parasitaemias compar
ed to unvaccinated and infected brook charr and rainbow trout. Complem
ent fixing antibodies were detected in vaccinated and challenged fish
2 weeks after challenge. Unvaccinated and infected brook charr had con
sistently higher titres of complement fixing antibody than unvaccinate
d and infected rainbow trout. Parasitaemias were lower in all fish in
which titres of complement fixing antibody were high. In a second expe
riment, brook charr inoculated intraperitoneally or intramuscularly wi
th 100000 C. salmositica per fish had high parasitaemias but no anaemi
a or other clinical signs. The results show that susceptible brook cha
rr do not suffer from cryptobiosis and may serve as reservoir hosts fo
r C. salmositica in areas where the disease is prevalent. Vaccination
to reduce the parasitaemia when fish become infected may be a control
strategy in these areas.