Fig. 1. Many red spots caused by the trematode in
bloody clam.
(Photo by K. Momoyama)
| Parasite | Tylocephalum sp. |
|---|---|
| Taxonomy | Plathyhelminthes, Cestoda, Lecanicephalidea |
| Host | Bloody clam (Anadara broughtonii) |
| Infection site | Muscle |
| Clinical sign | A red spotted cyst (1-2 mm) is observed in surface layer of the muscle. Cyst looks red since it is surrounded by the blood cells (Fig. 1). |
| Parasitology | Metacestoda stage of this parasite forms the visible cyst. |
| Pathology | Blood cells infiltrate the marginal region of the cyst, resulting in visualization of the lesion as ‘cysts’. No other information on pathology is available. |
| Health hazard | Since this parasite is not infectious to human, it is harmless in food hygiene. |
| Diagnosis | Flatten the lesion and observe the parasite under light microscope. |
| Other information | Cestodes of the genus Tylocephalum have been known to infect many shellfishes. However, red lesion occurs only in bloody clam because it possesses hemoglobin (Momoyama and Tensha, 2006). |
| References |
Momoyama, K. and K. Tensha (2006): Ugly-looking parasitic infections and other abnormalities of wild fish and shellfish caught in the coastal or inland waters around or in Yamaguchi Prefecture. Bull. Yamaguchi Pref. Fish. Res. Ctr., 4, 143-161. (In Japanese) |
