| Parasite | Pseudoterranova decipiens |
|---|---|
| Taxonomy | Nematoda, Secernentea, Anisakidae |
| Hosts | Japanese Spanish mackerel (Scomberomorus niphonius), chum salmon (Oncorhynchus keta), Pacific cod (Gadus macrocephalus), Alaska pollack (Theragra chalcogramma), Okhotsk atka mackerel (Pleurogrammus azonus), Japanese common squid (Todarodes pacificus), and many other marine fishes. |
| Infection site | Body cavity, visceral organs, muscle |
| Clinical sign | A filiform parasaite (ca. 3.5 cm length) which lacks the anterior part of the body was observed in Japanese Spanish mackerel (Fig. 1). |
| Parasitology | Final host is mainly Pinnipeds (seal, sealion, etc.). Released larva hatched from an egg is ingested by crustacean, e. g. euphausiid. Fishes are infected by eating such krill. The parasite body in fish is ca. 1-4 cm in length and red-brown in color. In a limited sense (sensu strict), ePseudoterranova decipiencef means only the one species P. decipience, meanwhile, in the broad sense (sensu lato), eP. decipiencef includes several species, which are genetically different each other (Paggi et al., 2000; Zhu et al., 2002). |
| Pathology | The effects of infection to the host are possibly low. |
| Health hazard | A live parasite, the causative agent of anisakiasis, penetrates into the wall of gut and causes the acute gastroenteritis, viz. violent abdominal pain, nausea and vomiting. Therefore, be careful when the host fishes is consumed raw. Heating or freezing to -20 C for 24 hours are effective for killing the parasite. |
| Diagnosis | Although the anterior part of the worm could not be observed, this parasite was diagnosed as P. decipience since the intestine is brownish yellow in color and the tail is conical and tapers from around the anus. |
| Other information | Pseudoterranova decipience parasitizes mainly wild coldwater fishes and squids. Hence, Hokkaido is the most reported location of Anisakiasis caused by P. decipience (Ishikura, 1999). |
| References | Ishikura, H. (1999): Anisakiasis (2) Clinical pathology and epidemiology.
Progress of medical parasitology in Japan. Meguro Parasitological Museum, 7, pp.439-464 (in Japanese). Paggi, L., S. Mattiucci, D. I. Gibson, B. Berland, G. Nascetti, R. Cianchi and L. Bullini (2000): Pseudoterranova decipiens species A and B (Nematoda, Ascaridoidae): nomenclatural designation, morphological diagnostic characters and genetic markers. Syst. Parasitol., 45, 185-197 . Zhu, X. Q., S. Dfamelio, H. W. Palm, L. Paggi, M. George-Nascimento and R. B. Gasse (2002): SSCP-based identification of members within the Pseudoterramova decipiens complex (Nematoda: Ascaridoidea: Anisakidae) using genetic markers in the internal transcribed spacers of ribosomal DNA. Parasitology, 124, 615-623. |
Fig. 2. The posterior end of Pseudoterranova.
(Photos by J. Araki)
Fig. 1. The nematode found in Japanese Spanish mackerel.