In vitro susceptibility of Plasmodium falciparum isolates to chloroquine and mefloquine in southeastern Mindanao Island, the Philippines.
Although the presence of multi-drug-resistant falciparum malaria has been reported in the Philippines, the distribution of drug-resistant malaria parasites has not yet been determined in Mindanao Island. In vitro susceptibility of P. falciparum to both chloroquine and mefloquine was assessed to forecast the spread of drug-resistant parasites in various foci in southeastern Mindanao Island. Of the 33 isolates of P. falciparum successfully tested, 10 (30%) were susceptible, 12 (36%) showed decreased susceptibility (80 nM < or = IC50 < 114 nM), and 11 (33%) were resistant (IC50 > or = 114 nM) to chloroquine. Ten (91%) of the resistant isolates and 9 (75%) of those with decreased susceptibility were from northern and northwestern Davao del Norte Province. Chloroquine-susceptible isolates were found among patients in the eastern parts of Davao del Norte and Davao Oriental provinces. Seven isolates from several foci in the study area were all mefloquine- susceptible (IC50 < 10 nM). This is the first report indicating the potential emergence of chloroquine-resistant P. falciparum on Mindanao Island, which is presently regarded as a drug-susceptible area.
Hatabu
Toshimitsu
T
International Medical Center of Japan, Tokyo, Japan.
Kawazu
Shin-ichiro
S
Suzuki
Jun
J
Valenzuela
Reuben F
RF
Villacorte
Elena A
EA
Suzuki
Mamoru
M
Rivera
Pilarita T
PT
Kano
Shigeyuki
S
D000293:Adolescent; D000328:Adult; D000818:Animals; D000962:Antimalarials / Q000494:pharmacology*; D002738:Chloroquine / Q000494:pharmacology*; D018432:Drug Resistance, Multiple; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D016778:Malaria, Falciparum / Q000188:drug therapy / Q000453:epidemiology; D008297:Male; D015767:Mefloquine / Q000494:pharmacology*; D021261:Parasitic Sensitivity Tests; D010679:Philippines / Q000453:epidemiology; D010963:Plasmodium falciparum / Q000187:drug effects*; D012111:Residence Characteristics
D000962:Antimalarials; D002738:Chloroquine; D015767:Mefloquine