Haplorchis pumilio

Haplorchis pumilio (Looss, 1896) Looss, 1899

(Figure 2-21)

ETYMOLOGY:Haplorchis = single testis and pumilio = a dwarf

SYNONYMS:Monostomum pumilio Looss, 1896; Monorchotrema taihokui Nishigori, 1924; Haplorchis taihokui Yamaguti, 1958; Haplorchis milvi Gohar, 1934; and Kasr aini Khalil, 1932.

HISTORY: This fluke was originally described from a pelican, Pelecanus onocrotalus, and a kite, Milvus migrans in Cairo Egypt. Haplorchis pumilio has been described from numerous hosts as a new species, it has also been confused with other species, i.e., Haplorchis taichui, and with parasites in other genera, i.e., Stellantochasmus falcatus (Pearson, 1964).

GEOGRAPHIC DISTRIBUTION: This trematode has a wide distribution. It has been reported from Egypt, Israel, Tunisia, China, Taiwan, India, and Australia.

LOCATION IN HOST: Small intestine.

PARASITE IDENTIFICATION: The genus Haplorchis (as is the related Procerovum) is characterized by possession of a single testis. The ventral sucker is posterior to the bifurcation of the intestine and contains the typical sucker/genital complex. Haplorchis can be differentiated from Procerovum by the in the possession in the latter of a very muscular wall on the seminal vesicle, called an expulsor, that runs along the intestinal cecum on the left side.

The species Haplorchis pumilio is a small fluke, 0.25 to 7.2 mm long by 0.1 to 0.19 mm wide. It differs from other species of Haplorchis in that the anterior edge of the ventral sucker is not lined with spines but with what has been called bars that number from 32 to 40. The eggs measure 29 to 32 µm by 15.5 to 17.5 µm.

LIFE CYCLE: The life cycle has elucidated by feeding kittens fresh-water fish, Gambusia, infected with cercariae that had developed in the snail Pirenella conica (Kuntz and Chandler, 1956).

CLINICAL PRESENTATION AND PATHOGENESIS: Not reported so thought to be asymptomatic.

TREATMENT: Probably praziquantel, but not reported.

EPIZOOTIOLOGY: Cats probably become infected by eating raw fish. Other animals that have been found naturally infected include among others, pelicans, kites, dogs, fox Vulpes vulpes), shrew (Crocidura olivieri), gulls, and human beings.

HAZARD TO OTHER ANIMALS: None known; however, due to the requirements for two intermediate hosts, it is unlikely that an infected cat would pose a direct threat to other animals.

HAZARD TO HUMANS: Humans have been infected, probably by the ingestion of the infected fish intermediate hosts.

CONTROL/PREVENTION: The prevention of the ingestion of raw fish.

REFERENCES:

Kuntz RE, Chandler AC. 1956. Studies on Egyptian trematodes with special reference to the Heterophyids of mammals. I. Adult flukes, with descriptions of Phagicolalongicollis n. sp., Cynodiplostomumnamrui n.sp., and a Stephanoprora from cats. J Parasitol. 42:445-459.

Pearson JC. 1964. A revision of the subfamily Haplorchiinae Looss, 1899 (Trematoda: Heterophyidae). Parasitology 54:601-676.

Figure 2-21.Haplorchispumilio from the small intestine of a domestic cat in Cairo, Egypt. Note the large single testis in the posterior of the body.

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