Therapeutic efficacy of chloroquine against uncomplicated, Plasmodium falciparum malaria in south-western Saudi Arabia

The results of annual random screening indicated that Plasmodium falciparum strains showing chloroquine (CQ) resistance in vitro became increasingly c ommon in the Jazan region of south-western Saudi Arabia between 1986 and 19 98 (chi (2) for trend = 50.027; P<0.001). This worrying trend and the emerg ence of a micro-epidemic in 1997-1998 prompted an assessment of the therape utic efficacy of CQ against uncomplicated, P. falciparum malaria in the are a. The in-vivo testing of sensitivity to CQ was carried out in 291 clinical ly manifest, microscopically positive cases of P. falciparum malaria. Most of these patients (88%) were successfully treated with a single standard re gimen of CQ therapy. The other 36 patients (12%) showed early treatment fai lure or a poor response to the CQ, although all of these were then successf ully treated with a single standard dose of sulfadoxine-pyrimethamine (Fans idar), as a replacement therapy. Those unsuccessfully treated with CQ were generally younger (t = 2.625; P = 0.01) and tended to have higher body temp eratures (t = 2.62; P = 0.012) and higher levels of parasitaemia at initial presentation (P>0.000) than those who responded well to the drug. Although CQ remains a reasonably effective drug for the treatment of malari a in the Jazan region, and therefore will be kept as the first-line drug fo r the foreseeable future, failure of CQ efficacy must be carefully monitore d in the area.