Critical Periods in Development of <i>Ichthyophthirius multifiliis</i> (Ciliophora) Populations<sup>1</sup>

Ewing, Margaret S.; Lynn, Melanie; Ewing, S. A.

doi:10.1111/j.1550-7408.1986.tb05628.x

Cited by 27 publications

(15 citation statements)

References 14 publications

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“…Ichthyophthirius multifiliis is known to have a thermally responsive life cycle (Ewing et al. ; Noe and Dickerson ; Matthews ; Aihua and Buchmann ) and has been identified as pathogenic in BC previously in the Skeena River, associated with high levels of prespawn mortality of returning adult sockeye salmon (Traxler et al. ).…”

Section: Resultsmentioning

confidence: 99%

Infectious disease, shifting climates, and opportunistic predators: cumulative factors potentially impacting wild salmon declines

Miller

Teffer

Tucker

et al. 2014

Evolutionary Applications

208

282

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Emerging diseases are impacting animals under high-density culture, yet few studies assess their importance to wild populations. Microparasites selected for enhanced virulence in culture settings should be less successful maintaining infectivity in wild populations, as once the host dies, there are limited opportunities to infect new individuals. Instead, moderately virulent microparasites persisting for long periods across multiple environments are of greatest concern. Evolved resistance to endemic microparasites may reduce susceptibilities, but as barriers to microparasite distributions are weakened, and environments become more stressful, unexposed populations may be impacted and pathogenicity enhanced. We provide an overview of the evolutionary and ecological impacts of infectious diseases in wild salmon and suggest ways in which modern technologies can elucidate the microparasites of greatest potential import. We present four case studies that resolve microparasite impacts on adult salmon migration success, impact of river warming on microparasite replication, and infection status on susceptibility to predation. Future health of wild salmon must be considered in a holistic context that includes the cumulative or synergistic impacts of multiple stressors. These approaches will identify populations at greatest risk, critically needed to manage and potentially ameliorate the shifts in current or future trajectories of wild populations.

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Section: Resultsmentioning

confidence: 99%

Infectious disease, shifting climates, and opportunistic predators: cumulative factors potentially impacting wild salmon declines

Miller

Teffer

Tucker

et al. 2014

Evolutionary Applications

208

282

View full text Add to dashboard Cite

show abstract

“…Relatively few research efforts have been devoted to the temperature and salinity dependent development of various strains of I. multifiliis since the presentation of the comprehensive work by Bauer (1958) and Wagner (1960). Stringent studies were conducted by MacLennan (1942), Ewing et al. (1986) and Noe and Dickerson (1995) on the trophont development in the skin of the host, but information about the tomocyst development and resulting theront production at various temperatures is otherwise lacking.…”

Section: Discussionmentioning

confidence: 99%

Temperature- and salinity-dependent development of a Nordic strain of Ichthyophthirius multifiliis from rainbow trout

Buchmann²

2001

J Appl Ichthyol

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SummaryDuring the twentieth century evidence was presented which suggested the presence of various strains and races of the parasite Ichthyophthirius multi®liis Fouquet. However, ecological pro®les of various parasite isolates from di erent climatic zones are sparse. Such stringent characterizations of parasite development at de®ned abiotic conditions could provide valuable criteria for the di erent races; pro®le comparison from various localities is one way to di erentiate these strains. Baseline investigations were therefore performed on the associations between abiotic factors (temperature/salinity) and the development of theronts in tomocysts of I. multi®liis isolated from rainbow trout in a Danish trout farm. It was shown that tomocyst formation and theront development took place between 5 and 30°C. Development rates and sizes of theronts were clearly a ected by temperature: theronts escaped tomocysts already after 16±27 h at 25°C and 30°C, whereas this process took 8±9 days at 5°C. Likewise, theront size decreased steadily from a maximum of 57.4´28.6 lm at 5°C to 28.6´20.0 lm at 30°C. This size variation was only partly associated with the number of theronts that appeared at di erent temperatures. The lowest number of theronts escaping from one tomocyst was indeed found at 5±7°C (mean 329±413). At 11.6, 17.0 and 21°C, the highest number of theronts appeared (mean 546±642). However, at 25 and 30°C, the number decreased (458 and 424, respectively). Additional studies on the salinity dependent development of the parasite (at 11.6°C) showed that salinities above 5 p.p.t. totally inhibited development. Even at 5 p.p.t. the developmental time signi®cantly increased and the number of theronts produced from one tomocyst decreased.

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“…The small number of infective 8 to 24 h trophonts recovered from nonimmune fish might, therefore, be attributed to slow developers and delayed transformation. There was no evidence of post 24 h trophonts directly invading new fish hosts, and by 72 h the parasites could have attained the threshold size for encystment and theront production within the aquatic environment (Maclennon 1937, 1942, Ewing et al 1986). We suggest that the infections established from post 72 h trophonts in the present study resulted from such a new generation of Fig.…”

Section: Level Of Infection Gglhigh M~t U R N Blow Dfree Horn Infectionmentioning

confidence: 99%

Ichthyophthiriasis in carp Cyprinus carpio:infectivity of trophonts prematurely exiting both the immune and non-immune host

Wahli

Matthews²

1999

Dis. Aquat. Org.

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Ichthyophthirius multifihis exposed to naturally immunised carp established short-term infections, the majority of parasites actively emerging within 2 h of entering the epidermis. A small, but significant, number of these expelled parasites were shown to retain theront-like properties with the capacity to directly re-invade a further fish host. Infectivity fell rapidly with time in the host and was comparable to that of trophonts of a similar age artificially induced to emerge from non-immune hosts with the aid of MEM (minimal essential medium). Trophonts recovered with MEM from immune carp 2 to 8 h post infection rarely established infections upon exposure to susceptible new hosts and no infections resulted from older trophonts recovered after 8 to 24 h exposure; older trophonts, however, represented only a small percentage of the original parasite population. A low level of infectivity was recorded in trophonts collected wlth the aid of MEM from non-immune carp after up to 24 h of infection. The results are discussed in relation to theront transformation and evasion of the host immune response.

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Critical Periods in Development of Ichthyophthirius multifiliis (Ciliophora) Populations¹

Cited by 27 publications

References 14 publications

Infectious disease, shifting climates, and opportunistic predators: cumulative factors potentially impacting wild salmon declines

Infectious disease, shifting climates, and opportunistic predators: cumulative factors potentially impacting wild salmon declines

Temperature- and salinity-dependent development of a Nordic strain of Ichthyophthirius multifiliis from rainbow trout

Ichthyophthiriasis in carp Cyprinus carpio:infectivity of trophonts prematurely exiting both the immune and non-immune host

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Critical Periods in Development of Ichthyophthirius multifiliis (Ciliophora) Populations1

Cited by 27 publications

References 14 publications

Infectious disease, shifting climates, and opportunistic predators: cumulative factors potentially impacting wild salmon declines

Infectious disease, shifting climates, and opportunistic predators: cumulative factors potentially impacting wild salmon declines

Temperature- and salinity-dependent development of a Nordic strain of Ichthyophthirius multifiliis from rainbow trout

Ichthyophthiriasis in carp Cyprinus carpio:infectivity of trophonts prematurely exiting both the immune and non-immune host

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Critical Periods in Development of Ichthyophthirius multifiliis (Ciliophora) Populations¹