Longitudinal survey of Plasmodium falciparum infection in Vietnam: characteristics of antimalarial resistance and their associated factors.

Plasmodium falciparum is the main cause of human malaria and is one of the important pathogens causing high rates of morbidity and mortality. The total number of malaria patients in Vietnam has gradually decreased over the last decade. However, the spread of pathogens with drug resistance remains a significant problem. Defining the trend in genotypes related to drug resistance is essential for the control of malaria in Vietnam. We undertook a longitudinal survey of Plasmodium falciparum malaria in 2001, 2002, and 2005 to 2007. The pfcrt, pfmdr1, pfdhfr, and pfdhps genes were analyzed by sequencing; and correlations by study year, age, gender, and genotype were identified statistically. The ratio of the chloroquine resistance genotype pfcrt 76T was found to have decreased rapidly after 2002. High numbers of mutations in the pfdhfr and pfdhps genes were observed only in 2001 and 2002, while the emergence of parasites with a new K540Y mutation in the P. falciparum dihydropteroate synthetase (PfDHPS) was observed in 2002. For males and those in younger age brackets, a correlation between vulnerability to P. falciparum infection and strains with pfcrt 76K or strains with decreased numbers of mutations in pfdhfr and pfdhps was demonstrated. The parasites with pfcrt 76T exhibited a greater number of mutations in pfdhfr and pfdhps.

Study of prevalence of mixed species malaria infection and distinguishment of recrudescence from re-infection in Gia Lai province by the use of nested polymerase chain reaction (PCR)

Application of PCR technique to survey component and mechanism of 4 human malaria parasites in Gia Lai province. These used bait couples were specificity for P.falciparum, P.vivax, P.malariae and P.ovale. The results showed that: there were the existance of 4 human malaria parasite species, of which P.falciparum was 57.6%, combination rate of 2,3,4 parasites species was 54.76%. To distinguish the recurrent, re-infection based on the difference of alleles in locus gen. 3 genes for highly polymorphic antigens: merozoite surface protein 1 (MSP1), merozoite surface protein 2 (MSP2), glutamate rich protein (GLURP). 11 patients were treated by fansidar had been recurrented after 14 days

Nested PCR definition of species composition of malaria parasites in Thanh commune, Huong Hoa district of Quang Tri province

Nested polymerase chain reaction (nested PCR) was applied to idennify species composition of four human malaria parasite species in Thanh commune, Huong Hoa district of Quang Tri province. The pair of primers specific to each species of P.falciparum, P.vivax, P.malariae and P.ovale were used. AND fragments specific to each species was 18ssr-RNA)[5], [10]. The analysis of 152 blood samples showed only two species of malaria parasites of P.falciparum (71%) and P.vivax (29%) present in the study area. Single P.falciparum infection rate was 65.8%, single P.vivax infection rate was 16.4% and the double infection of P.falciparum and P.vivax was 17.8%