Parasite	Kudoa sp.
Taxonomy	Myxozoa, Myxosporea, Multivalvulida
Host	North-Pacific giant octopus (Paroctopus dofleini)
Infection site	Muscle in the arm.
Clinical sign	The central region of the arm is liquefied, resulting in a large hole by the muscle breakdown (Fig. 1).
Parasitology	A spore is observed in the liquefied muscle tissue (Fig. 2). A spore (6-8 mm in diameter) has 4 polar capsules (ca. 2.5×1.5 mm). Life cycle is unknown.
Pathology	A post-mortem myoliquefaction may be caused by the proteolytic enzymes derived from the parasite.
Health hazard	Since this parasite is not infectious to human, it is harmless in food hygiene.
Diagnosis	Check the spores by wet-mount of the liquefied muscle. Sample should be smeared and stained by Giemsa or Diff-Quik.
Other information	An abnormal texture in the basal arm of a boiled north-Pacific giant octopus was found in a octopus processing plant. This parasite is only the species reported in octopus (Yokoyama and Masuda, 2001).
References	Yokoyama, H. and K. Masuda (2001): Kudoa sp. (Myxozoa) causing a post-mortem myoliquefaction of North-Pacific giant octopus Paroctopus dofleini (Cephalopoda: Octopodidae). Bull. Eur. Ass. Fish Pathol., 21, 266-268.

(Photos by K. Masuda)

Fig. 1. Liquefied (left) and healthy (right) arms of octopus.

Fig. 2. A Kudoa spore detected in the liquefied lesion.