Parasite	Microsporidium sp.
Taxonomy	Microspora, Microsporea
Host	Pacific saury (Cololabis saira)
Infection site	Trunk muscle
Clinical sign	White cysts (2-3 mm) are observed in the trunk muscle (Fig. 1).
Parasitology	Many bean-shaped spores were formed inside the cysts (Fig. 2). The presence of sporophorous vesicle has not been confirmed.
Pathology	No report
Health hazard	Since this parasite is not infectious to human, it is harmless in food hygiene.
Diagnosis	Check the spores by wet-mount of cysts. The sample should be smeared and stained by Uvitex 2B followed by a fluorescent microscopic observation. The stained spores emit blue fluorescence under UV radiation.
Other information	This parasite was found at a conveyor belt sushi restaurant. Until recently, Pacific saury has not been eaten raw, probably resulting in escape of the parasite from our attention. It might be an example of emerging parasite caused by a change of diet.
References	None

Fig. 1. Microsporidium cysts in the muscle of Pacific saury..

(Photos by S. Urawa)

Fig. 2. Fresh spores of Microsporidium sp.