Pathology of cultured paua Haliotis iris infectedwith a novel haplosporidian parasite, with some observations on the course of disease

Diseases of Aquatic Organisms

, S. Wakefield¹  B. K. Diggles¹  N. Cochennec-Laureau¹  R. D. Roberts¹  C. S. Friedman¹  J. Nichol¹  P. M. Hine¹ 

关键词: Haplosporidia;    Abalone;    Aquaculture;    Pathology;    Disease;    New Zealand;   

DOI  :  10.3354/dao050219

学科分类：生物科学（综合）

来源: Inter-Research

【 摘 要 】

ABSTRACT: Mortalities among juvenile paua Haliotis iris Martyn 1784 in a commercial culture facility were reported in April 2000. Histology of moribund paua showed heavy systemic infections of a uni- to multi-nucleate stage of a novel organismlater confirmed by transmission electron microscopy (TEM) and molecular studies to be a haplosporidian. Multinucleate plasmodia up to 25 µm diameter with up to 17 nuclei were detectable in wet preparations of hemolymph from heavily infected paua. Thepresence of the haplosporidian in the affected facility was associated with mortalities of slow growing Œrunt¹ paua during the summer months. Total mortalities in affected raceways 6 mo after mortalities began were between 82.5 and 90%. Heavily infectedpaua exhibited behavioural abnormalities including lethargy, loss of righting reflex, and were easily detached from surfaces. Some heavily infected paua exhibited oedema and pale lesions in the foot and mantle, but no reliable gross signs of disease werenoted. Light infections of the haplosporidian were also found in apparently healthy paua from the facility. Histology indicated that the early stages of infection were characterised by small numbers of plasmodia in the connective tissue surrounding thegut, amongst glial cells adjacent to nerves in the mantle and foot and within gill lamellae. In heavy infections, large numbers of small plasmodia (mean size 5.5 x 7 µm in histological sections) were present in the hemolymph,gills, heart, kidneys, mantle, foot, epipodium and connective tissue of the digestive gland. Infections were not transferred horizontally at 14 and 19°C after cohabiting heavily infected paua with uninfected paua for 3 mo in aquaria, or 3 mo afterinjecting healthy paua with hemolymph containing haplosporidian plasmodia. This may indicate that the prepatent period for disease is longer than 3 mo, that disease is not expressed below 20°C, or that an intermediate host is required for transmission.Spore formation was not observed in juvenile paua but sporocyst-like bodies containing putative spores were observed amongst haplosporidian plasmodia in the right kidney of poorly performing adult paua collected from the wild.

【 授权许可】

Unknown