Identification of Caligus parasites infesting Morone Labrax and its impact on fish health status and pathological alteration.

Abstract

The present study was aimed to investigate sea lice infestation including morphometric, molecular identification, disease prevalence and pathological tissue alterations in wild Sea bass (Morone Labrax) naturally collected from Ezbet Elborg, Damietta province, Egypt from October 2018 to end of August 2019. Design: Descriptive study Fish: 120 wild seabass (Morone Labrax) Procedures: The collected fish from Ezbet Elborg area, Damietta province, Egypt were clinically and parasitological investigated for the prevalence of sea lice parasite with molecular identification of the collected parasite samples with study of the pathological alteration of the affected tissue. Results:The study revealed that 48 fish (40%) of the examined fish were infested with Caligus clemensi, while the higher prevalence recorded during summer season (57%) followed spring (33%), autumn (10%) and no recording during winter. The molecular identification using 18-S rDNA was done with phylogenetic analysis compared with the previously recorded caligus species on database confirming the same results of parasitology. Histopathological examination of gills, buccal cavity revealed that the gill arch contained congested blood vessels beside edema, hemorrhage and inflammatory cells infiltration due to parasitic infestation. Conclusions and clinical relevance:Caligus infestation in wild sea bass caused by Caligus clemensi lead to mortalities due to pathological tissue alterations in gills and buccal cavity.

Co-infection with Caligus clemensi and Vibrio Parahaemolyticus in Egyptian Farmed Mullets: Diagnosis, Histopathology, and Therapeutic Management

“…This molecular evidence aligned with and bolstered our initial morphological identification, enabling definitive designation of C. clemensi as the causative species. Our results are consistent with previous reports from the Mediterranean basin documenting C. clemensi as a common ectoparasite of wild fish hosts [13]. However, our investigation newly reveals C. clemensi poses an escalating threat for Mediterranean mariculture, having expanded its distribution range from native tropical Indo-Pacific waters via human translocation [25].…”

“…Molecular diagnostic tools have revolutionized pathogen detection and enabled accurate identification of etiological agents compared to conventional methods [12]. For Caligus infections, PCR assays targeting the 18S rRNA gene have provided a specific means to identify the implicated parasite species without reliance on microscopic examination [13]. Currently, caligid control in fish farms relies predominantly on nonspecific chemical treatments with organophosphate compounds such as malathion [7][8][9][10][11][12][13][14].…”

“…For Caligus infections, PCR assays targeting the 18S rRNA gene have provided a specific means to identify the implicated parasite species without reliance on microscopic examination [13]. Currently, caligid control in fish farms relies predominantly on nonspecific chemical treatments with organophosphate compounds such as malathion [7][8][9][10][11][12][13][14]. However, these treatments have negative effects on the environment and may develop resistance in sea lice [15].…”

Global distribution patterns of Caligus Müller, 1785 (Copepoda: Caligidae) associated to teleost fishes, with physiological and histopathological data and description of treatment strategies

“…Infestations by Caligus spp. can cause the mortality in wild fish populations (Chatterji et al 1982, Hayward et al 2008, 2009, Abdelkalek et al 2021) and also result in economic losses due to mortality, reduced growth rate and poor feed conversion ratio among farmed fish populations (Rojas et al 2018, Arriagada et al 2019, leading to the use of chemical products to control and treat infestations in the hosts (Bravo et al 2010, Hamre et al 2011, Agusti et al 2016, Arriagada & Marín 2018, Arriagada et al 2019, 2020.…”