Published in PLOS One on 2026-09-11, this study is presented as an attributed evidence briefing. The excerpts below are the original researchers’ words, reproduced under their Creative Commons Attribution licence. Health Signal has selected the abstract and, where needed, opening background paragraphs; the complete methods, results, limitations and references remain in the linked paper.
Original authors: Debela Abdeta Efa, Megersa Akasa, Yobsan Tamiru, Clement Yaro
Source: PLOS One • DOI 10.1371/journal.pone.0357816
Read the complete primary study ↗ · Creative Commons Attribution licence
From the researchers
Abstract
An estimated 200 species of fishes of marine and freshwater fish are known to occur in Ethiopia. Fish parasites are the main cause of the significant threat to the fish biodiversity of Ethiopia’s freshwater islands. Lake Hawassa plays a central role in the local economy of the city which supports the artisanal fishing sector. The parasite of the fishes at lake Hawassa are hitherto poorly known and there are limited reports on the type of parasites across different fish hosts such as size, age, sex, condition factor, or other biological or ecological traits.
A cross-sectional study was carried out in 2023–2024 to estimate the prevalence of fish parasites and host factors. In the current survey Oreochromis niloticus (n = 135), Clarias gariepinus (n = 87), and Labeobarbus intermedius (n = 43) were sampled. Internal and external organs was inspected for the presence of the parasite affecting their health and wellbeing. Some external parasites were extracted from the fresh water immediately after fish were caught. The randomly selected host was classified based on species, sex, body weight, and the total body length. Parasites are identified morphologically at genera level using standard identification keys and pictorial guide. Analysed data were presented as frequencies, percentages, mean intensity, and mean abundance. Chi-square and P-values were considered for statistical association.
The parasite distribution varies with sex, body weight, and standard length of the studied fish. The overall infection/infestation rate is 88.30% (n = 234). A total of 1748 parasites classified under Nematodes (e.g., Contracaecum), Digenean trematodes (e.g., Clinostomum, Euclinostomum, Diplostomum, encysted metacercariae), Monogeneans (Dactylogyrus), Myxozoans (Myxobolus spp.), Crustacean ectoparasites (Argulus, Dolops), Hirudinea (leeches)was collected from O. niloticus (788), C. gariepinus (642) and L. intermedius (318). The internal parasites recovered from O. niloticus were Clinostomum (65.16%), Euclinostomum (34.07%), Contracaecum (26.67%), and Diplostomum (24.44%). Higher number of Myxobolus species, leeches, Argulus, and Dolops species was also recorded. Digenean encysted metacercaria (68.97%) and Contracaecum species (50.57%) are the most common parasite species infecting C. gariepinus. Diplostomum species, Dactylogyrus species, leeches, Argulus species, and Dolops species pose a serious threat to fish health in lake Hawassa. The mean intensity of the parasites in L. intermedius, C. gariepinus and O. niloticus was found to be 8.59, 7.92 and 6.79 while mean abundance is 7.40, 7.37 and 5.84 respectively.
This study found that various body parts are contaminated with one or more parasites. Some of those parasites have established zoonosis or cause cross infection to other fishes requiring urgent cooperation in performing pre-stock assessment for optimal production and maintaining the heath of fishery and hence human being.
Reading this evidence
Use the full paper to check the study design, participant selection, comparator and outcome definitions before drawing a practical conclusion. An association does not by itself show cause and effect. A reported performance measure needs its denominator and uncertainty. A finding from a particular facility, sample or time period should retain that scope when it is discussed elsewhere.
This briefing makes the source accessible within the wider research & evidence desk. It does not assess an individual patient or certify a product. When considering relevance to another health system, examine the original authors’ account of context and limitations, then seek local implementation evidence. The related reporting below provides other studies to read alongside this one; it is a topic connection, rather than a claim that their results are directly comparable.
© 2026 Debela Abdeta Efa, Megersa Akasa, Yobsan Tamiru, Clement Yaro. Excerpts reproduced under CC BY. Selection, formatting and contextual notes by Health Signal. The researchers are the authors of the source study, not members of Health Signal’s staff.
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