Biology of Cryptocaryon irritans and strategies for its control

An obligate parasite, Cryptocaryon irritans, which is responsible for the white spot disease of marine fish is known to develop in the temperature regime over 19°C. Recently, however, we found white spot disease of olive flounder Paralichthys olivaceus during winter at water temperatures ranging between 12 and 16°C in Korea. In the present study we isolated a C. irritans-like ciliate from the affected fish and investigated its reproductive characters to compare the newly found ciliate with typical C. irritans. The newly found ciliate had an additional process in the reproductive stage, characterized by a budding before palintomic division, and it showed a higher ability to carry out tomitogenesis at a low temperature (16°C) than at a high temperature (24°C). Nevertheless, the present ciliates still had much in common with typical C. irritans with respect to clinical, histopathological, and morphological characters, suggesting that it is a new strain of C. irritans, adapted to lower water temperature. KEY WORDS: Cryptocaryon irritans-like ciliate · White spot disease · Olive flounderResale or republication not permitted without written consent of the publisher

Section: Discussionmentioning

confidence: 48%

A new strain of Cryptocaryon irritans from the cultured olive flounder Paralichthys olivaceus

Jee¹,

Kim²,

Park³

et al. 2000

“…In controlled confinement, Cryptocaryon irritans can be controlled by changing the salinity of the water (Colorni 1987, Rigos et al 2001. Cheung et al (1979) likewise noted that lower salinity has an adverse effect on the development of this parasite.…”

Section: Discussionmentioning

confidence: 99%

“…Cryptocaryon irritans is currently becoming an issue of concern in aquaculture because of the high mortality of infected stocks. Colorni (1987) reported that the parasite has become a frequent pest in commercial fish farms, while mortality of about 50% in tank-cultured juvenile brown spotted grouper Epinephelus tauvina in Kuwait was reported by Rasheed (1989). In Japan, the red sea bream Pagrus major, the tiger puffer Takifugu rubripes and the flounder Paralichthys olivaceus cultured in marine net cages are also susceptible to the disease (Yoshinaga & Nakazoe 1997, Hirazawa et al 2001.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Cryptocaryon irritans, a parasite isolated from marine fishes in Taiwan

Yambot¹,

Song²,

Sung³

2003

The ciliated protozoan parasite Cryptocaryon irritans infecting marine fishes in Taiwan is described. Developmental characteristics and sequences of the ribosomal DNA regions such as part of 18 S, the entire first internal transcribed spacer, and part of 5.8 S of various Taiwan isolates of C. irritans were investigated. A total of 5 isolates was obtained from different fish-host species and localities, the majority from cultured fish species. C. irritans from Taiwan is able to shift its developmental characteristics, i.e. from non-adherent to adherent tomonts, from individualistic to aggregateforming tomonts, from infection of the gills only to infection of the gills and body. Thus, it is not possible to classify strains of C. irritans on the basis of these parameters. Premature tomonts that developed from dead fishes were able to produce theronts that could infect fish host. Isolates from Pingtung and the USA had identical nucleotide sequences while an isolate from Malaysia was identical to an Israel isolate. Percentage variation among pairs of Taiwan isolates showed a higher degree of variation than isolate sequences listed in GenBank. Sequence analysis revealed highly aberrant isolates in Taiwan, and a phylogenetic tree distinguished a marine and a low-salinity variant. C. irritans from marine fishes in Taiwan, therefore, display some characteristics not previously reported. Since manipulation of salinity in brackishwater ponds and marine cage sites is not feasible, there is a need to develop new strategies for the control and prevention of cryptocaryoniasis.

“…Upon excystment the theronts are liberated to infect new hosts. On average the whole life cycle is completed in around 9 to 10 d at 24 to 25OC (Colorni 1987).…”

Section: Cryptocaryon Irn'tansmentioning

confidence: 99%

Infections of Cryptocaryon irritans on wild fish from southeast Queensland, Australia

Diggles¹,

Lester²

1996

Wild-caught marine fish from 3 sites in SE Queensland, Australia, were examined over a period of up to 13 mo for infections of the parasitic ciliate Cryptocaryon irritans. Infections of C. irritans were found to be common on the fish sampled. Out of a total of 358 fish (14 species), 239 (66.7%) from 13 species were found to be infected. At Site 1 at the mouth of an estuary, the prevalence of C. irritans infections was 79% and the mean intensity was 12.9 parasites fish-'. At Site 2, a coastal bar area, the prevalence of infection dropped to 66 % and a mean intensity of 5.0 parasites fish-', whilst at Site 3 on the Great Barrier Reef, prevalence was lowest at 51 % with a mean intensity of 2.3 parasites fish-' The study concentrated on 2 sparid fishes, Acanthopagrus australis from Sites 1 and 2 and Gymnocranius audleyi from Site 3. The prevalence of infections on A. australis from Site 1 (n = 101) was 100% with a mean intensity of 14.6 parasites fish-', whilst at Site 2 (n = 74) the prevalence was 88 % at a mean intensity of 5.2 parasites fish-'. There was no apparent seasonality In prevalence or intensity of infections at Sites 1 and 2 despite water temperatures ranging between 15 and 27°C. At Site 3, the prevalence of infections of G. audleyi (n = 39) was 38% with a mean intensity of 1.9 parasites fish-'. The diameter of the tomonts collected from A. australis from Sites 1 and 2 vaned inversely with water temperature, and was not related to host size. Our results show that infections of C vntans are common on wild fish, not rare as previously thought. This may be partially due to the increased sensitivity of our tomont collection technique. Our data suggest that C. irritansmay exhibit a degree of host specificity in the wild, and also that its natural distribution can be extended into estuaries and seasonally into warm temperate waters.