Pygidiopsis genata Looss, 1907

(Figure 2-17)

ETYMOLOGY:Pygidiopsis (pygid=posterior; opsi=late) along with genata (referring to the genital opening).


HISTORY: This parasite was described by Looss (1907) from specimens recovered from a pelican, Pelecanus onocrotalus.

GEOGRAPHIC DISTRIBUTION: Naturally infected cats have been found in Europe, Egypt (29.2% of stray cats in Dakahlia, Abo-Shady et al., 1983), and Asia.

LOCATION IN HOST: Small intestine.

PARASITE IDENTIFICATION: The posterior end of the body is wider than the anterior body. the entire body is covered with small spines. Pygidiopsis has a two symmetrical testes and a single gonotyl. The worm is 0.4 to 0.7 mm long and 0.2 to 0.4 mm wide. The body is covered with small spines, and 16 larger spines surround the mouth. The eggs are 18 to 22 µm long by 9 to 12 µm wide.

LIFE CYCLE: The snail intermediate host is Melania tuberculata. The cercariae have a dorsal fin and eye spots. The cercariae encyst in brackish-water fish of the genus Tilapia (Boulos et al., 1981). Cats have been experimentally infected by the feeding of infected fish.


TREATMENT: Probably praziquantel, but not reported.

EPIZOOTIOLOGY: Cats become infected by eating raw fish. Chicks have also been shown to serve as experimental hosts of this trematode, and it is likely that the natural host is a marine bird.

HAZARD TO OTHER ANIMALS: None. Although other hosts are infected, the major means of infection is through the ingestion of the fish intermediate host which requires that the appropriate snail also be available. Thus, infection of these other hosts will typically only occur in the wild.

HAZARD TO HUMANS: Humans have been reported to be infected with this parasite in Egypt (Boulos et al., 1981). Infections were probably acquired by the ingestion of raw fish.

CONTROL/PREVENTION: Prevention of the ingestion of raw fish.


Abo-Shady AF, Ali MM, Abdel-Magied S. 1983. Helminth parasites of cats in Dakahlia, egypt. J Egypt Soc PArasitol 13:129-133,

Boulos LM, Abdou LA, Girgis RS. 1981. Histopathological and histochemical studies on experimentally infected hamsters with Pygidiopsisgenata. J Egypt Soc Parasitol 11:67-76.

Looss A. 1907. Notizen sur Helminthologie Aegyptiens. VII. Ueber einige neue Trematoden der ägyptischen Fauna. Centralbl Bakt Parasitenk Infekt 43:478-490.

Figure 2-17.Pygidiopsisgenata from the small intestine of a domestic cat in Cairo, Egypt.