Assessment of therapeutic efficacy of chloroquine for vivax malaria in Thailand.

Chloroquine-resistant Plasmodium vivax has been reported in some Asian countries. In 2003, 161 patients infected with vivax malaria were treated according to the Thai National Drug Policy, with oral chloroquine (approximately 25 mg base/kg body weight, administered over 3 days) followed by primaquine on day 28 (15 mg daily for 14 days). All the patients were initially cured after chloroquine treatment, clearing their parasitemias within 7 days. Only one patient presented with parasitemia at 28 days. These data indicate that chloroquine is still effective for the treatment of patients with vivax malaria in Thailand.

Monitoring the therapeutic efficacy of antimalarials against uncomplicated falciparum malaria in Thailand.

Increasing antimalarial drug-resistance is an important problem in Thailand. The results of monitoring the antimalarial efficacy are used in decision-making about using antimalarials to treat uncomplicated falciparum malaria in Thailand. In 2002, 552 patients with uncomplicated malaria were treated according to the Thai National Drug Policy, with mefloquine 25 mg/kg plus artesunate 12 mg/kg and primaquine 30 mg in divided doses for 2 days in high-mefloquine-resistant areas; mefloquine 15 mg/kg plus primaquine 30 mg in non- or low-mefloquine-resistant areas; mefloquine 15 mg/kg plus artesunate 12 mg/kg and primaquine 30 mg in divided doses for 2 days or Coartem (6-dose regimen for adult contains 480 mg artemether and 2880 mg lumefantrine) plus primaquine 30 mg given over 3 days in moderate-mefloquine-resistant areas. The study shows that mefloquine, artesunate plus mefloquine, and artemether plus lumefantrine are effective in the treatment of uncomplicated malaria in most areas of Thailand except for Ranong and Kanchanaburi, where the first-line treatment regimen should be revised.