[Artesunate in interrupting the transmission of Plasmodium falciparum].

OBJECTIVE: To observe the effect of artesunate (ATS) on the infectivity of Plasmodium falciparum gametocytes (PFG). METHODS: 31 volunteers with falciparum malaria and gametocytaemia were randomly divided into 3 groups: artesunate (ATS) group (15 cases), quinine (QN) group (10 cases) and placebo group (6 cases). Each case in ATS group received 6-day course of oral artesunate (200 mg at 0, 6 and 24 hours then 100 mg daily for 4 days). Cases in QN group each received 21-dose course of quinine sulfate (500 mg/time) over seven days. Cases in placebo group took 2 tablets of vitamin B composites, three times per day for seven days. Peripheral PFG were counted daily in all cases until the clearance of PFG. Mosquitoes (Anopheles dirus) were fed with venous blood of patients on the 1st, 7th, 14th, 21st and 28th day, respectively. RESULTS: All cases in placebo group were PFG positive at the whole course by blood smear examinations. The PFG relative density in ATS group were (12.5+/-3.3)%, (1.2+/-0.4)%, (0.3+/-0.1)% on 7th, 14th, 21st day respectively, and the mean PFG clearance time was (22.0+/-1.4) d. The PFG relative density in QN group were (173.9+/-47.0)%, (112.5+/-45.4)%, (32.5+/-17.8)% at 7th, 14th, 21st day respectively, and the mean clearance time of PFG was (32.5+/-2.1) d (t=4.731, P<0.01). PFG remained positive on the 28th day in placebo group. The infectivity test to mosquitoes showed on 14th day the positive rate in ATS group, QN group and placebo group were 0, 35.0% and 48.7% respectively. In ATS group, the sporozoite rate of anopheline mosquitoes were 14.8% and 0 at 7th, 14th day, while in QN group, 142.0%, 98.6% and 20.3% at 7th, 14th, 21st day respectively. In placebo group, the infection rate of sporozoites remained stable. CONCLUSION: Oral administration of artesunate with a total dosage of 1000 mg in 6 days inhibits the infectivity of PFG.

[A randomized comparative study of naphtoquine, mefloquine and artsunate in the treatment of falciparum malaria].

OBJECTIVE: To evaluate the efficacy and safety of naphtoquine, compared with mefloquine and artesunate in the treatment of falciparum malaria. METHOD: Ninety patients with falciparum malaria were randomly allocated to 3 groups, including naphtoquine, mefloquine and artesunate group. In the naphtoquine group, thirty patients were prescribed single daily dosage of 1,000 mg for one day. In the mefloquine group, equal patients were treated with single dosage of 750 mg. Another thirty patients in the artesunate group were given total dosage of 600 mg for five days and doubling dosage on the first day. RESULT: In all three groups, symptoms were well controlled. The average fever-subsidence time in naphtoquine group was 30 h +/- 16 h and approximate that in mefloquine group (24 h +/- 15 h, P>0.05), but was longer than that in naphtoquine group (18 h +/- 9 h, P<0.01). The average parasite-clearance time in naphtoquine group (98 h +/- 28 h) is longer than that in mefloquine group (57 h +/- 20 h, P<0.01) and that in artesunate group (43 h +/- 17 h, P<0.01). At the end of 28-day clinical trail, the curative ratio in naphtoquine group was the highest (96.7%), and was significantly higher than that in mefloquine group (76.7%, P<0.05) and artesunate group (73.3%, P<0.05). Slight nausea and vomiting were observed in few patient in three groups. CONCLUSION: Although the average fever-subsidence time and the parasite-clearance time of naphtoquine at single 24-hour dosage of 1,000 mg were longer than those of mefloquine and artesunate, the 28-day curative ratio of naphtoquine was higher than that of mefloquine and artesunate. So we recommend that the combination of artemisinin, which is a rapid action antimalarial, and naphtoquine or mefloquine, which are longterm action antimalarial, would contribute to promoting efficacy, shorting the period of treatment and delaying occurrence of drug resistance.