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Outbreak of Swim Bladder Inflammation Caused by Sphaerospora dykovae in Koi (Cyprinus carpio koi) in Taiwan
Hao-Kai Chang1, Yi-An Chen2, Yu-Lun Tsai1, Ying-Chen Wu1, Jui-Hung Shien2, Woon-Fa Chang3, Shih-Ling Hsuan1* and Cheng-Chung Lin1*
1Graduate Institute of Veterinary Pathobiology; 2Department of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan; 3Animal Disease Diagnostic Center, National Chung Hsing University, Taichung, Taiwan
*Corresponding author: (CCL); (SLH)


SBI has had a severe economic impact on the fish industry in central Europe, but the present study is the first to describe an outbreak of SBI in Koi in Taiwan, even in Asia. A group of 7-month-old koi (Cyprinus carpio koi) showed abnormal swimming behavior and abdominal distension with a fatality rate of 40%. Smear examination of swim bladders showed numerous identical basophilic spherical organisms. Gross examination revealed severe adhesion of abdominal organs and erosion, enlarged of the swim bladder. Severe inflammation of the submucosal layer of the swim bladder and large numbers of pansporocysts and zygospores were noted microscopically with Hematoxylin and Eosin stain, Giemsa and modified Grocott's methenamine silver (GMS) stain. The nucleotide sequence of the pathogens isolated from the fish samples had a 99% homology with Sphaerospora dykovae, the pathogenic agent in swim bladder inflammation (SBI).

Key words: Cyprinus carpio koi, Sphaerospora dykovae, Swim bladder inflammation, Taiwan


ISSN 0253-8318 (Print)
ISSN 2074-7764 (Online)