Euryhelmis cotti (Simon, 1972) is an intestinal fluke with a complex life history with three hosts; in the metacercarial stage, E. cotti infects fish in the family Cottidae. Our objective was to determine the distribution, prevalence, and intensity of infection of E. cotti in shorthead sculpin (Cottus confusus Bailey and Bond, 1963) in Birch Creek, Idaho. We collected shorthead sculpin at five sites in Birch Creek with a backpack electrofisher and determined prevalence and intensity of infection on sculpin by counting metacercariae on the fins and body of each fish. We found shorthead sculpin with metacercariae at all sites. Prevalence of the parasite was lowest at the downstream sites (33.9% – 41.0%) and was higher at the upstream sites (> 83.2%). Mean intensity of infection on each fish ranged from 1.2 metacercariae per fish (S.E. = 0.08) at the site furthest downstream to 215.1 metacercariae per fish (S.E. = 19.06) at the site furthest upstream. High prevalence and intensity of infection in shorthead sculpin at upstream sites may have negative effects on fitness of the fish (e.g., reductions in growth, reproduction, survival, swimming performance) and warrants further research.

中文翻译：

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爱达荷州桦树溪短头杜鹃中吸虫寄生虫感染率和强度的变化

Euryhelmis cotti (Simon, 1972) 是一种具有复杂生活史的肠吸虫，具有三个宿主；在囊蚴阶段，E. cotti 感染 Cottidae 科的鱼。我们的目标是确定爱达荷州桦树溪的短头杜鹃（Cottus confusus Bailey 和 Bond，1963 年）中 E. cotti 感染的分布、流行率和强度。我们使用背包电鱼在 Birch Creek 的五个地点收集了短头杜鹃，并通过计算每条鱼的鳍和身体上的囊蚴来确定杜鹃的感染率和强度。我们在所有地点都发现了带有囊蚴的短头杜鹃。寄生虫的流行率在下游站点最低（33.9% – 41.0%），在上游站点更高（> 83.2%）。每条鱼的平均感染强度范围为每条鱼 1.2 个包蚴（SE = 0. 08）在最下游的地点，在最上游的地点每条鱼有 215.1 个包蚴（SE = 19.06）。上游地点短头杜鹃的高流行率和感染强度可能对鱼的健康产生负面影响（例如，生长、繁殖、存活、游泳性能下降），值得进一步研究。