Prohemistomum vivax (Sonsino, 1893) Azim, 1933
(Fig. 2-3)
ETYMOLOGY:Pro (anterior) + hemi (half) + stomum (mouth) and vivax (lively).
SYNONYMS:Prohemistomum spinulosum Odhner, 1913.
HISTORY: This species was first described from worms collected from a kite, Milvusmigransaegypticus.
GEOGRAPHIC DISTRIBUTION: Egypt (Abo-Shady et al.; 1983 Fahmy et al., 1984 found this parasite in 19 of 29 stray cats.) and Israel (Witenberg, 1934).
LOCATION IN HOST: Small intestine.
PARASITE IDENTIFICATION: These are very small trematodes that are about 1 mm in length. They differ from Mesostephanus in that the overall body shape is oval rather than elongate.
LIFE CYCLE: The life cycle of Prohemistomum vivax was initially elucidated by Azim (1933) under the synonym Prohemistomum spinulosum. Azim found that brackish and fresh-water fishes (Gambusia affinis and Tilapia nilotica) could serve as the second intermediate host. More recently, El-Naffar et al., (1985) showed that the metacercaria of this fluke is found in the muscles of several fish genera, including Tilapia, Hydrocyon, Alestes, Schibe, and Eutropius. The adult parasites were recovered from the duodenum, jejunum, and ileum of kittens about 6 days after they were fed the metacercariae harvested from fish in Lake Nasser, Egypt. Work with the related species Prohemistomum chandleri has disclosed that the metacercaria contain some reproductive structures and appears to require only a few days to develop to the adult stage after a fish is eaten by a final host (Vernberg, 1952).
CLINICAL PRESENTATION AND PATHOGENESIS: Asymptomatic.
TREATMENT: Probably praziquantel but not reported.
EPIZOOTIOLOGY: Cats become infected by eating fish containing the metacercariae. The flukes are capable of developing to the adult stage in a few days.
HAZARD TO OTHER ANIMALS: None.
HAZARD TO HUMANS: None.
CONTROL/PREVENTION: Prevent cats from eating raw fish.
REFERENCES:
Abo-Shady AF, Ali MM, Abdel-Magied S. 1983. Helminth parasites of cats in Dakahlia, Egypt. J Egypt Soc Parasitol 13:129-133.
Azim MA. 1933. On Prohemistomumvivax (Sonsino, 1892) and its development from cercaria vivax Sonsino, 1892. Ztschr Parasitenk 5:432-436.
El-Naffar MK, Saoud MF, Hassan IM. 1985. Role played by fish in transmitting some trematodes of dogs and cats at Asswan Province, A.R. Egypt. Assiut Vet Med J 14:57-67.
Fahmy MA, Arafa MS, Khalifa R, Abdel-Rahman AM, Mounib ME. 1984. Studies on helminth parasites in some small mammals in Assiut Governorate. 1. Trematode Parasites. Assiut Vet Med J 11:43-52.
Vernberg WG. 1952. Studies on the trematode family Cyathocotylidae Poche, 1926, with the description of a new species of Holostephanus from fish and the life history of Prohemistomumchandleri sp. nov. J Parasitol 38:327-340.
Witenberg G. 1934. Parasitic worms of dogs and cats in Palestine. Vet Rec 14:232-239.
Figure 2-3.Prohemistomumvivax recovered from a cat in Egypt.