Treatment of vivax malaria on the western border of Thailand

Abstract

The efficacy of chloroquine (25 mg base/kg over 3 days) in Plasmodium vivax malaria was evaluated in 1995/96 in 342 patients living in an endemic area on the western border of Thailand. Clearance of fever and parasites was obtained within 2 days in > 95% of the patients, and all were aparasitaemic by day 4. Reappearance of P. vivax occurred in 1 patient on day 21 and in 8 by day 28, giving a 28-day cure rate of 97% [95% confidence interval (CI) 95-99%]. By day 63, the relapse/re-infection rate was 63% (95% CI 57-69%). Most reappearances of parasitaemia (85%; 121/143) were symptomatic. These patients were retreated either with chloroquine alone (n = 70) or with chloroquine and primaquine (0.25 mg/kg daily for 14 days) (n = 43). Only 1 patient (in the chloroquine-only group) had prolonged parasite clearance (D8) and he developed recurrent P. vivax by day 21 suggesting possible recrudescence. The addition of primaquine to chloroquine reduced the risk of having a third vivax episode within 2 months by 96% (95% CI 83-99%). This resulted in a significantly higher haematocrit at day 42 despite a greater decrease in haematocrit during the first week of treatment with chloroquine-primaquine (P = 0.04). Chloroquine remains highly effective on the western border of Thailand and the use of strictly supervised primaquine effectively prevents relapse. The introduction of primaquine on a large scale in an endemic area still requires a long-term risk-benefit assessment which must take into account potential toxicity, low compliance and reductions in the incidence and severity of P. falciparum infections by co-existent P. vivax.

Factors associated with recurrent Plasmodium vivax malaria in Porto Velho, Rondônia State, Brazil, 2009

“…Based on the operational classification of recurrences proposed by the PNCM, 29.5% of P. vivax recurrences in Porto Velho in 2009 were probable relapses. It is quite probable that this estimated proportion is close to the true proportion of relapses in the study population, because the reappearance of P. vivax in relapses after a primary infection occurred between 28 days (3%) and 63 days (63%) in a study in Thailand 28 . Furthermore, P. vivax recurrence was observed between 28 and 90 days in 70% of patients studied in French Guiana, although recrudescence and Cad.…”

Association of Genetic Mutations in Plasmodium vivax dhfr with Resistance to Sulfadoxine-Pyrimethamine: Geographical and Clinical Correlates

“…S-P use is rare in Madagascar and the Comoros Islands and has been relatively infrequent in India. Although chloroquine is also used to treat vivax malaria in Thailand (7,22), the prevalence of highly chloroquine-resistant falciparum malaria resulted for a time in the widespread use of S-P. This compound is still available widely in areas where malaria is endemic and is still a first-line treatment in the adjacent countries Laos and Myanmar.…”

Therapeutic Responses of Plasmodium vivax Malaria to Chloroquine and Primaquine Treatment in Northeastern Myanmar

“…Clinical observations in Thailand in the past showed either complete sensitivity (29)(30)(31)(32) or only small proportions of patients developing recurrent parasitemia within 28 days (33,34). Similarly, in the neighboring region of China's Yunnan Province, longitudinal monitoring suggested that CQ efficacy remained relatively unchanged, with 1.5% (9/603) patients experiencing late clinical failure (35).…”