DAO 126:167-172 (2017)  -  DOI: https://doi.org/10.3354/dao03166

NOTE
Locally extensive meningoencephalitis caused by Miamiensis avidus (syn. Philasterides dicentrarchi) in a zebra shark 

Wen-Ta Li1, Chieh Lo2, Chen-Yi Su2, Hsuan Kuo1, Susanne Je-Han Lin1, Hui-Wei Chang1, Victor Fei Pang1, Chian-Ren Jeng1,*

1Graduate Institute of Molecular and Comparative Pathobiology, School of Veterinary Medicine, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd, Taipei 10617, Taiwan, ROC
2Farglory Ocean Park, No.189, Yenliao Village, Shoufong Township, Hualien, Taiwan, ROC
*Corresponding author:

ABSTRACT: Scuticociliatosis, caused by ciliated protozoa in the subclass Scuticociliatia of the phylum Ciliophora, can cause fatal disease in teleost fish species. However, information on scuticociliatosis in elasmobranchs is still scarce. In this report, we describe a case of locally extensive meningoencephalitis caused by Miamiensis avidus (syn. Philasterides dicentrarchi) in a 2 yr old captive zebra shark Stegostoma fasciatum. Granulocytic meningoencephalitis was observed through histological assessment. Inflammation was confined to the ventral aspect of the brain with a large number of ciliated protozoa, transforming into non-suppurative meningitis in the lateral aspect, and gradually vanished in the dorsal aspect. No histopathological and polymerase chain reaction (PCR) evidence of systemic dissemination of M. avidus was found. PCR targeting the gene coding the small-subunit ribosomal RNA (SSUrRNA) of M. avidus was performed on the brain, liver, and gill tissues, and only brain tissue yielded a positive result. The DNA sequences from amplicons of the protozoal SSUrRNA gene were completely matched to that of M. avidus. The distribution of protozoa in the current case was mainly located in the brain and suggests the possibility of a direct neural invasive pathway of M. avidus through the nasal cavity/ampullary system and/or a unique tissue tropism of M. avidus specific to the brain in zebra sharks. Further investigations on the pathogenesis of M. avidus in elasmobranchs, especially zebra sharks, are needed.


KEY WORDS: Scuticociliatosis · Scuticociliatosis · Tissue tropism · Neural invasive pathway · Small-subunit ribosomal RNA (SSUrRNA) · Ciliated protozoa


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Cite this article as: Li WT, Lo C, Su CY, Kuo H and others (2017) Locally extensive meningoencephalitis caused by Miamiensis avidus (syn. Philasterides dicentrarchi) in a zebra shark . Dis Aquat Org 126:167-172. https://doi.org/10.3354/dao03166

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