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Epidemiology of Eustrongylides sp. Infection in Triplophysa strauchii: Temporal Dynamics and Risk Factors
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Xinjiang Key Laboratory for Ecological Adaptation and Evolution of Extreme Environment Organisms, College of Life Sciences, Xinjiang Agricultural University, Urumqi 830000, China
2
Postdoctoral Research Station of Animal Husbandry, Xinjiang Agricultural University, Urumqi 830052, China
*
Author to whom correspondence should be addressed.
Vet. Sci. 2026, 13(7), 625; https://doi.org/10.3390/vetsci13070625 (registering DOI)
Submission received: 23 May 2026
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Revised: 18 June 2026
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Accepted: 24 June 2026
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Published: 26 June 2026
Simple Summary
Eustrongylides is a parasitic nematode whose life cycle involves fish as second intermediate hosts and piscivorous waterbirds as definitive hosts. In humans, the consumption of undercooked, infected fish can lead to gastrointestinal symptoms such as enteritis and diarrhea. This study reports, for the first time, the infection of a local fish called Triplophysa strauchii in Xinjiang, China. After checking 720 fish over eight months, we found that one in five carried the worms. Infections peaked in spring and late summer. Larger fish were more often infected and harboured more worms, and the effect of body length varied significantly across months. This new finding matters for food safety and fishery management in cold wetlands.
Abstract
The epidemiology of the nematode Eustrongylides sp. remains poorly understood in natural fish populations, especially under alpine conditions. This study investigated its infection dynamics in Triplophysa strauchii, an endemic fish in an alpine wetland in northwestern China. A total of 720 fish were sampled monthly from April to November 2025. Parasitic larvae were identified using ribosomal ITS sequences. Hurdle models were employed to assess infection risk and intensity, incorporating host length, sex, and month as predictors. The overall prevalence was 21.8%, with a mean intensity of 4.36 ± 6.83 worms per infected fish. Infection dynamics showed two seasonal peaks: a spring peak with high intensity and a late-summer peak with moderate prevalence but low intensity. Host length was the most stable predictor for both infection risk (OR = 1.916 per cm, 95% CI: 1.232–2.977) and intensity, with significant length × month interactions (length × May: IRR = 4.847, p = 0.005; length × November: OR = 0.418, p = 0.005), indicating seasonal modulation of the length effect. These findings provide foundational insights into parasite transmission in alpine wetlands and highlight public health concerns regarding fish consumption.
