A new record of Clinostomum philippinensis (Valasquez, 1959) in Trichogaster microlepis (Gunther, 1861) from Bung Borapet, Nakhon Sawan, Thailand.

Thirty-six freshwater fish from Bung Borapet, a large reservoir, were examined for helminths in July 2005. The prevalence of infection was 19.44 (7/36) and the intensity was 4.67 (168/36) per fish. Seven fish were infected with 4 species of helminths: 1 trematode, Clinostomum philippinensis (metacercariae); 1 cestode, Senga chiangmaiensis; 1 acanthocephalan, Pallisentis sp and 1 nematode, Camallanus anabantis. An encysted metacercaria of Clinostomum philippinensis was found in the gills of Trichogaster microlepis. The present study is a new report of Clinostomum metacercariae in the second intermediate host, T. microlepsis, in Thailand. Future work should investigate the epidemiology of the metacercarial stage in the intermediate host and the adult in the experimental definitive host.

In vitro effects of aqueous extract from Artocarpus takoocha Roxb on tegumental surface of Haplorchis taichui.

The tegumental surface of the adult intestinal fluke, Haplorchis taichui, after in vitro incubation in Tyrode's solution containing 25, 50, 75 and 100% of aqueous extract of Artocarpus takoocha for 1, 6, 12 and 24 hours, was monitored by Scanning Electron Microscopy (SEM). The effect on worm motility was studied in contemporizing period. The adult worms stopped their motility immediately after being incubated with 25, 50, 75 and 100% of aqueous extract of A. takoocha. Observed under a light microscope, most worms showed bubbling from the oral sucker, ventral sucker and excretory pore. After exposure to the solution, SEM observation showed large blebs protruding from the oral sucker, ventral sucker and excretory pore. The surface damage was composed of numerous small blebs, followed later by the disruption of tegument. The severity of damage increased due to the increasing of aqueous extract of A. takoocha and incubation periods.

High prevalence of Haplorchis taichui metacercariae in cyprinoid fish from Chiang Mai Province, Thailand.

This study aimed to investigate Haplorchis taichui metacercarial infection in fish collected from the Chom Thong and Mae Taeng districts, Chiang Mai Province during November 2001 to October 2002. A total 617 cyprinoid fish of 15 species were randomly collected and examined for H. taichui metacercariae. All the species of fish were found to be infected with H. taichui. The infection rates were 91.4% (266/290) and 83.8% (274/327), with mean intensities of 242.9 and 107.4 in the Chom Thong and Mae Taeng districts, respectively. The portion of the fish body with the highest metacercarial density was the muscles, and second, the head, in both districts. In addition, the fish had mixed-infection with other species of trematodes, namely: Centrocestus caninus, Haplorchoides sp, and Haplorchis pumilio.

Recovery and growth of Haplorchis taichui (Trematoda: Heterophyidae) in chicks.

An experimental study was performed to observe the recovery and growth of a minute intestinal fluke, Haplorchis taichui in chicks (Gallus gallus domesticus). Metacercariae of H. taichui were isolated from Jullien's mud carp, Henicorhynchus siamensis, which were collected in the Chiang Mai Province, Thailand. Two hundred metacercariae were orally force-fed to each chick. The intestine of the chicks were examined from day 1 to day 54 post-infection (PI). The incidence of infection was 84.9% (28/33) and the mean intensity was 19.9 (656/33), with the range 0-59. The worm recovery rate was the highest at day 11 PI (29.5%). On day 3 PI, mature adult worms were recovered and 1-200 eggs were observed in the uterus of the worms. The worms grew rapidly in the chicks and the genital organs were fully developed in 14 days. This parasite can survive in chicks up to day 48 PI. It is concluded that they are a suitable definitive host for infection with H. taichui.