A survey of helminth infection in rats (Rattus spp) from Chiang Mai Moat

An investigation of helminths in the Norway (brown) rat, Rattus norvegicus, and roof rat, Rattus rattus, from Chiang Mai Moat during May to August 1995, was done. Thirty-three out of thirty-eight trapped rats were infected (86.84%); 16 R. norvegicus (100%) and 17/22 R. rattus (77.27%). The rat was infected with 10 helminth species: 4 trematodes, Centrocestus sp (2.63%), Echinostoma ilocanum (10.52%), Echinostoma malayanum (10.52%) and Quinqueseralis quinqueseralis (39.47%); 2 cestodes, Raillietina sp (36.64%) and Taenia sp (cysticercus) (7.89%); and 4 nematodes, Angiostrongylus cantonensis (42.10%). Nippostrongylus sp (34.21%), Rictularia sp (52.63%) and egg of Capillaria hepatica (7.89%). The helminths were found in the small intestine (84.21%), large intestine (42.10%), lung (36.64%), stomach (28.94%), heart (23.94%), and liver (15.78%). The female Norway rats were infected with 10 species of helminths and the males with 6 species. In the roof rat, 7 species of helminths were found in females and 6 species in males.

Occurrence of two heterophyid metacercariae Haplorchis and Haplorchoides in cyprinoid fish of some districts in Chiang Mai and Lumphun Province

According to currently available information, the metacercaria of one heterophyid trematode, Haplorchis, is commonly found in freshwater fishes, especially the cyprinoid group. Thus, in an investigation into the level of Haplorchis metacercaria infection in cyprinoid fishes, comprising ten species, 811 cyprinoid fishes were captured from canals, reservoirs and rivers in six districts of Chiang Mai Province and 4 districts of Lumphun Province, Thailand, 43.03% of the fishes comprising seven species viz Puntius leiacanthus, P. gonionotus, P. orphoides, P. stolickkae, Cirrhina spp, Rasbora spp and R. lateristriata, were found infected, with the prevalence of infection at 77.29, 70.31, 56.52, 47.14, 18.48, 7.94 and 5.18% respectively. Infected fishes were collected from Mae Rim and Sansai districts of Chiang Mai, and Pasang, Ban Hong and Li districts of Lumphun. It should be noted that the Haplorchis metacercariae are commonly found along with Haplorchoides metacercariae. Both minute heterophyids metacercariae were mainly localized in scales, a few were found in fins and gills of fishes.

Experimental host of Stellantchasmus falcatus

The purpose of this research was to determine the incidence and intensity of infection in experimental host of minute intestinal trematode, Stellantchasmus falcatus (family Heterophyidae). Experimental hosts consisting of uninfected mice (Mus musculus) and one-day-old chicks (Gallus gallus domesticus) were orally force fed with a hundred metacercariae of S. falcatus obtained from the body cavity of the freshwater fish Dermogenys pusillus. The worms, then, were checked from 24 hours to 30 days post-infection. The heterophyid flukes were distributed in the ileum and jejunum of the chicks and small intestine of mice with 70% (21/30) and 80% (24/30) of incidence and intensity of infection range from 1-44 (24.6) and 1-67 (7.8), respectively. The body size of S. falcatus at 24 hours; was 0.1-0.15 (0.13) x 0.29-0.39 (0.33) mm in chicks and 0.14-0.17 (0.15) x 0.29-0.32 (0.3) mm in mice. The maximum length and width of the worms were found within 5 days post-infection, of 0.2-0.25 (0.22) x 0.49-0.62 (0.55) in chicks and 0.19-0.22 (0.2) x 0.38-0.52 (0.44) mm in mice. Developing egg was found in the second day after infection and the number of egg increase with the age of the parasite. Embryonated eggs were recovered in the feces of mice 9 day post-infection. S. falcatus infection in the other experimental host was done in rat (Rattus norvegicus), but rats were fed with whole number of metacercariae which found in a body cavity of fish, D. pusillus. The results appear to be the same as in the chicks and mice.