RESUMEN
Resistance of Plasmodium falciparum to antimalarial drugs is widespread in many countries in Africa; including Mozambique; and it makes the control of malaria difficult. Sulfadoxina-pyrimethamine (SP) is the most common alternative; used as first-or second-line drug in malaria endemic areas where the parasites are tesistant to chloroquine (CQ). However; there is a concern that the extensive use of SP may lead to rapid emergency of P. falciparum resistant strains. Using molecular markers that have been correlated to SP resistance; we carried out the studies presented in this thesis; where the mai objective was to assess the levels of resistance and to study the mocecular markers that underline the dynamics of resistance to sulfadoxine-pyrimethamine. The studies were conducted in Manhica district; an area of intense and perennial malarial transmission in southern Mozambique. Chapter 1 gives ageneral introduction; the rationale and the objective of the study. In chapter 2 the background informationof the study area; the study population; study design and the laboratory procedures used are presented; with more emphasis on the methods used to identify the genotypes in the P. falciparum dhfr/dhps genes. The findings of the field studies are reported in chapters 3 to 6 as summarized below. Chapter 3 reports results of the study on the efficacy of chloroquine (CQ); sufadoxine-pyrimethamine (SP) and amodiaquine(AQ) among children with incomplicated malaria. Chapter 4 describe results of the study investigating the correlation between the presence of mutations in the dhfr and dhps genes of P falciparum and the in vivi outcome following SP traetment of children under five years of age in Manhica district; southern Mozambique. Chapter 5 present the results of a study investigating the frequency of mutation halotypes in the dhfr and dhps genes of P. falciparum; at the community level. Chapter 6 presents results of a study exploring mothers' treatment-seeking behavioral regarding fever and childhood malaria and assessing the level of usage of antimalarial drugs by the community. Chapter 7 discuss the main findings of all chapters; summarizes the conclusions of all studies and discusses areas for future research