Southeast Asian J Trop Med Public Health

The efficacy of quinine and artemetherthe effective blood schizontocide in malarial treatmenthas been in vitro tested with the advanced third-stage larvae of Gnathostoma spinigerum. All larvae were collected from freshwater eel (Fluta alba) and exposed to the culture medium, each containing either quinine dihydrochloride or artemether at a final concentration of 20 μg/ml and 0.5 μg/ml, respectively for 21 consecutive days. Larval motility was assessed daily and the topographical changes were assessed using scanning electron microscope after 21-days of drug exposure. All worms moved actively for 21 days of study period and no change in surface ultrastructure was observed. Quinine and artemether at these concentrations have no effect on movement and topographical changes on the advanced third-stage larvae of this parasite. Correspondence: Kom Sukontason E-mail: [email protected] QUININE AND ARTEMETHER ON GNATHOSTOMA Vol 31 No. 2 June 2000 413 were maintained at 37oC under 5% CO 2 in air. The larval motility of each group was assessed daily during this study period according to the criteria of Kiuchi et al (1987) before they were examined for topographical changes by SEM. Following removal, all incubated larvae were briefly washed in 0.1 M phosphate buffer prior to fixation for electron microscopy. Cultured larvae were fixed in a fixative agent consisting of 2.5% glutaraldehyde at 4oC for 24 hours. The fixed worms were subjected to postfix in 1% osmium tetroxide and dehydration in a graded alcohol series, followed by acetone and critical-pointed drying. The worms were then mounted on stubs and coated with gold. Ten larvae from each group were viewed with a JEOL-JSM840A scanning electron microscope at an accelerating voltage of 20 kV, and photographed with KodakVerichrome Panchromatic film VP 120. Regarding the mobility of aL3 G. spinigerum, those incubated in quinine, artemether and in the control groups moved actively with the whole body for all 21 days. No dead and/or weaken worms were found. As for the examination of surface morphology under SEM, aL3 G. spinigerum in both drug-treated and control groups were of normal appearance as previously described (Anantaphruti et al, 1982; Ratanarapee, 1982; Maleewong et al, 1988). No change in surface ultrastructure was observed after the experimental period of 21 days (Fig 1). The results from mobility and SEM showed that quinine and artemether were not effective on aL3 G. spinigerum. Disappearance of acute clinical symptoms after treatment with quinine proposed by Jaroonvesana and Harinasuta (1973) may not be the effect of drug in killing or immobilizing parasites. However, quinine itself has an anti-inflammatory effect (Santos and Rao, 1998) and inhibits the release of enzyme beta-glucoronidase from stimulated polymorphonuclear leukocytes (Fontagne et al, 1989). Disappearance of acute symptoms also occurred after both albendazole and placebo treatment (Kraivichian et al, 1992). Additionally, albendazole has proved to be effective on the motility of aL3 after 9 days of drug exposure (Sukontason et al, 1999). Disappearance of acute symptoms may be due to the course of disease itself and/or increment by drugs that have an anti-inflammatory property. Artemether, another potent blood schizontocide drug for human malaria parasites, has had a promising effect on the early infection of Schistosoma japonicum in dogs, rabbits (Xiao et al, 1995a,b) and humans (Song et al, 1998). It can reduce the phosphobycerate kinase and pyruvate kinase enzymes in the glycolytic pathway of this parasite (Xiao et al, 1998). However, all studies were only involved in the early infection by both immature and small sized parasites. Artemether Fig 1–Scanning electron micrographs of advanced thirdstage larvae Gnathostoma spinigerum. (A) Control. (B) Exposed in vitro to quinine dihydrochloride at a concentration of 20 μg/ml for 21 days. (C) Exposed in vitro to artemether at a concentration of 0.5 μg/ ml for 21 days. SOUTHEAST ASIAN J TROP MED PUBLIC HEALTH Vol 31 No. 2 June 2000 414 at a concentration of 0.5 μg/ml for 21 days has proved not to be effective on aL3 G. spinigerum. A higher concentration may or may not have any effect on this stage of parasite, however, the therapeutic index must be considered. We thank the Faculty of Medicine, Chiang Mai University, for supporting this research.