MBUGI,ERASTO2025-03-042025-03-042004https://www.suaire.sua.ac.tz/handle/123456789/6604ThesisThe study was aimed at molecular investigation of multiplicity of infections and drug resistance to sulphadoxine-pyrimethamine (SP) in Plasmodium falciparum malaria. This molecular epidemiological study involved 141 blood samples from patients aged less than five years from malaria-endemic Mlimba division of Kilombero District, Morogoro, south eastern Tanzania. Blood samples were collected on filter papers (3MM Whatmann) and parasite DNA was extracted by Chelex technique. Molecular analysis on the merozoite surface protein 2 (MSP2), dihydrofolate reductase (DHFR) and dihydropteroate synthase (DHPS) was based on polymerase chain reaction (PCR) followed by restriction fragment length polymorphism (RFLP) of PCR products (PCR-RFLP). These techniques made it possible to determine the multiplicity of infections and SP resistance-associated point mutations anticipated at sorting out recrudescence from new infections. The commonly reported point mutations occurring at codons 51, 59, 108 and 164 in the DHFR and codons 437, 540 and 581 in the DHPS domains were investigated. The results showed the multiplicity of infection array of single to six infections per patient with an average multiplicity of 2.58 infections per patient. Fifty-one patients possessed single alleles of either allelic families of the MSP2 gene in PCR-RFLP successful samples. Double, triple and multiple infections were detected in 37.7%, 11.9% and 5.9% of patients, respectively. Regarding drug resistance molecular markers, 66.9% carried mutations at codon 108, 62.7% at codon 51 and 48.8% at codon 59 of DHFR domain. Fifty-six (43.7%) of samples carried mutations at codon 437, 39.2% at codon 540 and 0.8% at codon 581 on the DHPS domain. Proportions of mixed variants in the DHFR domain ranged from 0 - 21.5% and 0.8 - 6.3% in the DHPS domain. About 44 (36.4%) of isolatesiii harboured triple mutant DHFR genotypes, whereas quintuple mutation was observed in 24 (19.8%) of isolates. Ten (8.3%) isolates possessed at least double DHFR and double DHPS mutants. This study found a high proportion of SP resistance- associated point mutations in Mlimba two years after deployment of SP as a first-line antimalarial drug in Tanzania. However, the adequate clinical response (81.1%) observed clinically reflects the role of semi-immunity component in the study population. This implies that used molecular markers for monitoring drug resistance, be done simultaneously with studies on confounding factors pertaining to development of resistance against SP in falciparum malaria. The extensive use of antifolates other than SP for treatment of infections other than malaria is a probable candidate for potentiating selection of mutations ascribed to SP resistance. The SP resistance potential detected in this study, caution on its useful therapeutic life as an interim first-line drug against malaria in TanzaniaenMolecular investigationDrug resistancePyrimethamine (sp)Plasmodium falciparumMalariaThesis