Haplorchis taichui (Nishigori, 1924) Witenberg, 1930
ETYMOLOGY:Haplorchis = single testis and taichui = for Dr. Taichu
SYNONYMS:Monorchotrema yokogawai Katsuta, 1932; Monorchotrema taihokui Nishigori, 1924; Monorchotrema taihokui Africa and Garcia, 1935; Haplorchis rayi Saxena, 1955.
HISTORY: This fluke was originally described from specimens collected from a night heron, Nycticorax nycticorax in Taiwan. Experimental infections has been produced in human beings, dogs, cats, and mice (Faust and Nishigori, 1926).
GEOGRAPHIC DISTRIBUTION: This trematode has a wide distribution throughout Asia and the Mediterranean that is very similar to that of Haplorchis yokogawai although it has not been observed in Australia (Pearson, 1964).
LOCATION IN HOST: Small intestine.
PARASITE IDENTIFICATION: Haplorchis taichui differs from the other species of Haplorchis found in the cat in that the ventral sucker is covered with a small number (12 to 16) of large spines (25 to 30 µm long) rather than with hooks as in Haplorchis pumilio or a many small spines as in Haplorchis yokogawai.
The species Haplorchis taichui is a small fluke that is rather wide, 0.45 to 0.89 mm long by 0.21 to 0.32 mm wide. The eggs measure 24 to 28 µm by 12 to 15 µm.
LIFE CYCLE: The life cycle has elucidated by the feeding of infected brackish-water mullet to human beings, dogs, and cats (Faust and Nishigori, 1926). The snail host in Taiwan is Melania reiniana. The fish hosts in Taiwan with members of the Cyprinidae, Siluridae, and Colitidae. In Palestine, Witenberg (1929) found the infected fish to be of the genera Barbus, Tilapia, and Mugil.
CLINICAL PRESENTATION AND PATHOGENESIS: Not reported but hought to be asymptomatic.
TREATMENT: Probably praziquantel, but not reported.
EPIZOOTIOLOGY: Cats become infected by eating raw fish. Other hosts that ingest infected raw fish are also likely to become infected. The normal natural hosts are probably piscivorous birds.
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 (Kliks and Tantachamrun, 1974) in Thailand by the ingestion of the infected fish intermediate hosts.
CONTROL/PREVENTION: The prevention of the ingestion of raw fish.
Faust EC, Nishigori M. 1926. The life cycles of two new species of Heterophyidae parasitic in mammals and birds. J Parasitol 13:91-128.
Kliks M, Tantachamrun T. 1974. Heterophyid (Trematoda) parasites of cats in North Thailand, with notes on a human case found at necropsy. Southeast Asian J Trop Med Pub Hlth 5:547-555.
Witenberg, G. 1929. Studies on the trematode family Heterophyidae. Ann Trop Med Parasitol 23:131-239.
Figure 2-23.Haplorchistaichui from a kite, Milvusmigrans, in Egypt.*