Three cases of human gnathostomiasis caused by Gnathostoma hispidum, with particular reference to the identification of parasitic larvae.

Human gnathostomiasis is well known to be caused by Gnathostoma spinigerum, G. hispidum, G. doloresi and G. nipponicum in Japan. In the present reported cases, skin biopsies were performed on three Japanese patients. As a result, cross sections of the larvae were clearly observed in the biopsied specimens. All cross sectioned larvae had an intestinal canal, which consisted from 25-35 cells. A large nucleus was observed at the center of each intestinal cell. The morphological features completely correlated with the characteristics of larval G. hispidum. Based on these findings, all three human cases were thus determined to be confirmed cases of gnathostomiasis caused by G. hispidum.

Epidemiology of clonorchiasis in Ninh Binh Province, Vietnam.

Clinical and stool examinations for clonorchiasis were carried out in an endemic area, Kim Son District, Ninh Binh Province, Vietnam. Stool examination with the Kato-Katz technic revealed that in 306 residents selected randomly, 42 people (13.7%) were infected with Clonorchis sinensis. The rate was biased towards men (23.4%) as opposed to women (1.5%) and increased with age. No children younger than 10 years old were infected, reflecting difference in a chance for acquisition of infection through a habit of eating raw fish. Few clinical abnormalities were found by blood and urine examinations of the patients. Treatment with praziquantel decreased the infection rate to 5.3% at 6 weeks later. Snails, Melanoides tuberculatus, collected from ponds around the settlements were infected with cercariae at a rate of 13.3%. Farmed fish (Hypophthalmichtys molitrix) in the ponds were infected with metacercariae at rates of 56.4% in small individuals and 100% in large ones. The life cycle of C. sinensis is exclusively completed in the ponds and the traditional habit of eating raw fish in summer was thought to be a major route of infection.

Studies on chemotherapy of parasitic helminths: efficacy of artemether on Japanese strain of Schistosoma japonicum in mice.

Effects of artemether were examined on Schistosoma japonicum in mice. When the drug was given at a daily dosage of 200 mg/kg for 4 successive days from 46 days post-infection, a significant reduction in worm recovery was observed. A significant reduction in size of worms from the medicated mice was also seen compared with that from non-medicated controls.

Scanning electron microscopic observations of first- and third-stage larvae and adults of Angiostrongylus costaricensis.

The surfaces of larval and adult Angiostrongylus costaricensis, causative agent of human abdominal granuloma, were studied by the use of scanning electron microscopy. Cuticular annulations were clearly demonstrated on the surface of larvae and adults. Differences in the appearance of alae in larval stages and in the shape of the tail at different stages of development are described and illustrated. Several aspects of morphology previously unreported for this parasite are also described.

Effect of tea on 12-O tetradecanoyl-phorbol-13 acetate (TPA) induced promotion of transformation in JB6 mouse epidermal cells.

The extract of black and green tea (Camellia sp.) which are widely consumed as commonest beverage, decreased the 12-O-Tetradecanoylphorbol-13 acetate (TPA) induced promotion of transformation in dose dependent manner in JB6 mouse epidermal cell system. The probable mechanisms have been discussed.

In vivo efficacy of levamisole against larval stages of Angiostrongylus cantonensis and A. costaricensis.

Anti-larval effects of levamisole were examined on A. cantonensis in rats and A. costaricensis in mice. 1) In rats inoculated with 40 infective larvae of A. cantonensis: Compared with a non-treated control group, a significant reduction in number of worms recovered was seen in the group receiving a single dose of 1.0 mg/kg or more. A significant decrease in host lung-body weight ratio was seen in the group receiving drug of 3.0 mg/kg or more. 2) In mice inoculated with 20 infective larvae of A. costaricensis. In the non-treated control group, a severe loss in body weight and death of host animals were observed. A single dose of 30 mg/kg on 3, 4 or 5 days post-infection remarkably inhibited these changes. At 30 mg/kg for 3 or 7 days levamisole was more effective than a single dose of the drug. These results suggest that levamisole has conspicuous in vivo effects against larval stages of A. costaricensis as well as A. cantonensis.

Motility and drug susceptibility of Angiostrongylus cantonensis developing from gamma-irradiated first-stage larvae.

The effects of neuropharmacological agents on the motility of irradiated and non-irradiated Angiostrongylus cantonensis adult females were studied. GABA induced complete paralysis in non-irradiated and 5,000 R-irradiated worms, but caused only slight paralysis on 10,000 R-irradiated worms. The paralytic effect of GABA was antagonised by picrotoxin. The reason for low susceptibility of heavily irradiated worms to GABA is not known. There was no difference in susceptibility of non-irradiated and irradiated worms to other neuropharmacological agents including eserine, phenylephrine and dibenamine.