Temporal Evolution of the Resistance Genotypes of Plasmodium Falciparum in Isolates From Equatorial Guinea During 20 Years (1999 to 2019).

Abstract

Background: Malaria is one of the deadliest disease in the world, particularly in Africa. The resistance to antimalarial drugs is one of the most important problems to global malaria control. The study assess the evolution of the different resistance markers over time and the possible influence of the interventions and treatment changes that have been made in Equatorial Guinea.Methods: 1223 biological samples distributed from 1999 to 2019 were included in the study. The screening of the mutations in pfdhfr, pfdhps, pfmdr1 and pfcrt genes were carried out by nested PCR and RFLPs, and the study of pfk13 genes was carried out by nested PCR, followed by sequencing to determine the presence of mutations Results: the haplotypes partially and fully resistant (pfdhfr + pfdhps) increase over time. In 2019, the fully resistant is increasing although super resistant remains lower. There is also a continued decline over time in pfmdr1 and pfcrt gene mutations. Since 2008, when ACTs were introduced in the country, the number of mutations detected in pfk13 has been increasing over time, with more mutations being observed in 2019. In this year, were detected 2 synonymous and 5 non-synonymous mutations, although are not related to resistance to ACTs. In addition, the non-synonymous A578S mutation, the most frequent on the African continent, was detected in 2013, although it has not been detected in the following years.Conclusions: The withdrawal of the use of CQ as a treatment in the country has been effective over time, as wild-type parasite populations outnumber mutant populations. The upward trend observed in SP resistance markers evidence its misuse alone or in combination with AS or AQ in some areas of the country, this allows selective pressure from SP to continue. SNPs 540E and 581G do not exceed the limit of 50% and 10% respectively, which means that SP as an IPT is still effective in the country. As for the pfk13 gene, no mutations have been detected in relation to resistance to ACTs. However, in 2019 there is a greater accumulation of non-synonymous mutations compared to years prior to 2008.