The prevalence and degree of resistance of <i>Plasmodium falciparum</i> to first-line antimalarial drugs : An in vitro study from a malaria endemic region in Yemen.

• Main Authors: Al-Shamahy Hassan, Al-Harazy Abdullilah, Harmal Nabil, Al-Kabsi Abdulgodos
• Format: Article
• Language: English
• Published: King Faisal Specialist Hospital and Research Centre 2007-01-01
• Series: Annals of Saudi Medicine
• Online Access: http://www.saudiannals.net/article.asp?issn=0256-4947;year=2007;volume=27;issue=6;spage=432;epage=436;aulast=Al-Shamahy

<b>Background: </b> Unpublished studies on antimalarial drug efficacy have found low levels of chloroquine resis-tance in Yemen. This study was carried out to determine the current prevalence of drug resistance in Plasmodium falciparum in Yemen to the main anti-malarial drugs and to determine the efective concentration (EC) values. <b> Methods:</b> The WHO standard protocol was used for the selection of subjects, collection of blood samples, culture techniques, examination of post-culture blood slides and interpretation of results. The in vitro micro-test Mark III was used for assessing susceptibility of P .falciprum isolates. <b> Results:</b> The criteria for blood parasite density was met by 219 P. falciprum malaria patients. Chloroquine resistance was found in 47&#x0025; of isolated P. falciparum schizonts. Mefloquine resistance was found in 5.2&#x0025;. In addition, the EC50 and EC95 values in blood that inhibited schizont maturation in resistant isolates were higher than the normal therapeutic level for mefloquine. No resistance occurred against quinine or artemisinin, with no growth at the cut-off level for quinine and inhibition at low concentrations of artemisinin. <b> Conclusion:</b> Our study confirmed the occurrence of chloroquine-resistant P. falciparum and a slow increase in the rate of this resistance; it is likely that resistance will increase further and spread over all the foci of malaria in Yemen. The low rate of mefloquine-resistant P. falciparum, was lower than that reported in Africa or Southeast Asia, but it is the first report of mefloquine resistance in Yemen. Finally, the isolates were sensitive to low con--centrations of quinine and artemisinin.