The decreasing efficacy of chloroquine in the treatment of Plasmodium vivax malaria, in Sanliurfa, south-eastern Turkey.

In most regions of the world, chloroquine has been the standard treatment for Plasmodium vivax malaria for more than 50 years. Recently, however, chloroquine-resistant P. vivax has been reported from Oceania, several parts of Asia, and South America. In June-August 2004, therapeutic failure following chloroquine treatment of acute P. vivax malaria was investigated among 91 patients from two sites (Karacadag and Sekerli) in the Turkish province of Sanliurfa. Each patient received a directly observed, standard, chloroquine treatment (10 mg/kg on each of days 0 and 1 and 5 mg/kg on day 2), before being followed-up for 28 days. Overall, 19 (20.9%) of the patients - 11 (23.7%) of the 46 from Karacadag and eight (17.3%) of the 45 from Sekerli - were identified as treatment failures between day 3 and day 28. The cumulative incidence of treatment failure recorded in the present study (0.219) was markedly higher than that recorded, in a similar study at the same sites, in September 2002 (0.135). Although the relatively small samples meant that this difference was not statistically significant, it seems likely that the efficacy of chloroquine for the treatment of P. vivax in Sanliurfa province is decreasing quite rapidly.