The first report of diplostomiasis from cultured rainbow trout (Oncorhynchus mykiss) in Turkey

Abstract

Metacercariae of the Diplostomum spp., the cause of Larval Eye Diplostomiasis (LED), are located in the lenses of the eyes of fresh water fish and cause degeneration, lens opacity and blindness as disease progresses. Feed uptake is hindered in fish with failing eyesight causing loss of apetite and mortality becomes inevitable with the onset of secondary diseases. Freshwater molluscs and waterfowl have an important role in the fast spread of the disease to nearby farms. In this work, a total of 534 trout samples obtained from 24 farms located in southeastern Turkey were examined for LED. Histopathological findings were evaluated in thirty fish with lens opacity in varying degrees. Also these fish were examined in terms of bacterial agents as well. As a result of this work, Diplostomum spp. metacercariae were found to be prevalent in the lenses of fish. In fish with marked lens opacity, focal to extensive subcapsular cataract was observed. Cataract lesions included abnormal proliferation of the lens epithelium at the site of capsular rupture, often followed by degeneration, fragmentation and liquefaction of adjacent cortical lens fibers. Additionally, Lactococcus garvieae was also isolated in 10 of 24 farms

Keywords

• Diplostomiasis
• Rainbow trout

Türkiye'deki gökkuşağı alabalıklarında (Oncorhynchus mykiss) ilk Diplostomiasis bildirimi

Abstract

Larval Göz Diplostomias (LED)’in etkeni olan Diplostomum spp.'nin metaserkerleri tatlı su balıklarının göz lenslerinde yerleşerek hastalık ilerledikçe dejenerasyon, lenslerde opasite (katarakt) ve körlüğe yol açmaktadır. Görme yetisini kaybeden balıklarda yem alımı engellenmektedir ve bu durum iştah kaybına yol açmakta ve sekonder enfeksiyonların da gelişmesi ile birlikte mortalite kaçınılmaz hale gelmektedir. Tatlı su yumuşakçaları ve su kuşları hastalığın yakın çiftliklere hızla yayılmasında önemli role sahiptir. Bu çalışmada, Türkiye'nin güneydoğusunda bulunan 24 balık çiftliğinden toplanan 534 alabalık örneği LED açısından muayene edilmiştir. Değişen derecelerde lens opasitesi gösteren 30 balıkta histopatolojik bulgular değerlendirilmiştir. Ayrıca, bu balıklar bakteriyel etkenler açısından da incelenmiştir. Bu çalışmanın sonucunda, Diplostomum spp. metaserkerleri balıkların lenslerinde yaygın olarak tespit edilmiştir. Belirgin lens opaklığı görülen balıklarda fokalden yaygına değişen subkapsüler katarakt gözlemlenmiştir. Katarakt lezyonları lens epitelinin kapsüler ruptur bölgesinde anormal proliferasyonu ile sıklıkla bunu izleyen dejenerasyon, fragmentasyon ve bitişik kortikal lens liflerinde sıvılaşma belirtilerini içermektedir. Buna ek olarak, 24 çiftliğin 10'unda Lactococcus garvieae de izole edilmiştir

Keywords

• Diplostomiasis
• Gökkuşağı alabalığı

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