title: Profile of molecular mutations in pfdhfr, pfdhps, pfmdr1, and pfcrt genes of Plasmodium falciparum related to resistance to different anti-malarial drugs in the Bata District (Equatorial Guinea).
abstract: The emergence of drug resistance in Plasmodium falciparum has been a major contributor to the global burden of malaria. Drug resistance complicates treatment, and it is one of the most important problems in malaria control. This study assessed the level of mutations in P. falciparum genes, pfdhfr, pfdhps, pfmdr1, and pfcrt, related to resistance to different anti-malarial drugs, in the Continental Region of Equatorial Guinea, after 8 years of implementing artesunate combination therapies as the first-line treatment.
  
  
  
  A triple mutant of pfdhfr (51I/59R/108N), which conferred resistance to sulfadoxine/pyrimethamine (SP), was found in 78% of samples from rural settings; its frequency was significantly different between urban and rural settings (p = 0.007). The 164L mutation was detected for the first time in this area, in rural settings (1.4%). We also identified three classes of previously described mutants and their frequencies: the partially resistant (pfdhfr 51I/59R/108N + pfdhps 437G), found at 54% (95% CI 47.75-60.25); the fully resistant (pfdhfr 51I/59R/108N + pfdhps 437G/540E), found at 28% (95% CI 7.07-14.93); and the super resistant (pfdhfr 51I/59R/108N + pfdhps 437G/540E/581G), found at 6% (95% CI 0.48-4.32). A double mutation in pfmdr1 (86Y + 1246Y) was detected at 2% (95% CI 0.24-3.76) frequency, distributed in both urban and rural samples. A combination of single mutations in the pfmdr1 and pfcrt genes (86Y + 76T), which was related to resistance to chloroquine and amodiaquine, was detected in 22% (95% CI 16.8-27.2) of samples from the area.
  
  
  
  The high level of mutations detected in P. falciparum genes related to SP resistance could be linked to the unsuccessful withdrawal of SP treatment in this area. Drug resistance can reduce the efficacy of intermittent prophylactic treatment with SP for children under 5 years old and for pregnant women. Although a high number of mutations was detected, the efficacy of the first-line treatment, artemisinin/amodiaquine, was not affected. To avoid increases in the numbers, occurrence, and spread of mutations, and to protect the population, the Ministry of Health should ensure that health centres and hospitals are supplied with appropriate first-line treatments for malaria.
authors.affiliation: Malaria Laboratory, National Centre of Tropical Medicine, Institute of Health Carlos III, C/Monforte de Lemos 5, 28029, Madrid, Spain. pberzosa@isciii.es.|Network Collaborative Research in Tropical Diseases, RICET, Madrid, Spain. pberzosa@isciii.es.
authors.forename: Pedro
authors.initials: P
authors.lastname: Berzosa
authors.affiliation: Malaria Laboratory, National Centre of Tropical Medicine, Institute of Health Carlos III, C/Monforte de Lemos 5, 28029, Madrid, Spain.
authors.forename: Andrés
authors.initials: A
authors.lastname: Esteban-Cantos
authors.affiliation: Malaria Laboratory, National Centre of Tropical Medicine, Institute of Health Carlos III, C/Monforte de Lemos 5, 28029, Madrid, Spain.|Network Collaborative Research in Tropical Diseases, RICET, Madrid, Spain.
authors.forename: Luz
authors.initials: L
authors.lastname: García
authors.affiliation: Malaria Laboratory, National Centre of Tropical Medicine, Institute of Health Carlos III, C/Monforte de Lemos 5, 28029, Madrid, Spain.|Network Collaborative Research in Tropical Diseases, RICET, Madrid, Spain.
authors.forename: Vicenta
authors.initials: V
authors.lastname: González
authors.affiliation: Malaria Laboratory, National Centre of Tropical Medicine, Institute of Health Carlos III, C/Monforte de Lemos 5, 28029, Madrid, Spain.
authors.forename: Marisa
authors.initials: M
authors.lastname: Navarro
authors.affiliation: Malaria Laboratory, National Centre of Tropical Medicine, Institute of Health Carlos III, C/Monforte de Lemos 5, 28029, Madrid, Spain.
authors.forename: Taiomara
authors.initials: T
authors.lastname: Fernández
authors.affiliation: Malaria Laboratory, National Centre of Tropical Medicine, Institute of Health Carlos III, C/Monforte de Lemos 5, 28029, Madrid, Spain.|Network Collaborative Research in Tropical Diseases, RICET, Madrid, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Romay-Barja
authors.affiliation: Malaria Laboratory, National Centre of Tropical Medicine, Institute of Health Carlos III, C/Monforte de Lemos 5, 28029, Madrid, Spain.
authors.forename: Zaida
authors.initials: Z
authors.lastname: Herrador
authors.affiliation: National Centre of Microbiology, Institute of Health Carlos III, Madrid, Spain.
authors.forename: José Miguel
authors.initials: JM
authors.lastname: Rubio
authors.affiliation: Malaria Laboratory, National Centre of Tropical Medicine, Institute of Health Carlos III, C/Monforte de Lemos 5, 28029, Madrid, Spain.|Ministry of Health and Social Welfare of Equatorial Guinea, Malabo, Equatorial Guinea.
authors.forename: Policarpo
authors.initials: P
authors.lastname: Ncogo
authors.affiliation: Instituto Universitario de Enfermedades Tropicales y Salud Pública de Canarias, Universidad de la Laguna, Tenerife, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Santana-Morales
authors.affiliation: Network Collaborative Research in Tropical Diseases, RICET, Madrid, Spain.|Instituto Universitario de Enfermedades Tropicales y Salud Pública de Canarias, Universidad de la Laguna, Tenerife, Spain.
authors.forename: Basilio
authors.initials: B
authors.lastname: Valladares
authors.affiliation: Ministry of Health and Social Welfare of Equatorial Guinea, Malabo, Equatorial Guinea.
authors.forename: Matilde
authors.initials: M
authors.lastname: Riloha
authors.affiliation: Malaria Laboratory, National Centre of Tropical Medicine, Institute of Health Carlos III, C/Monforte de Lemos 5, 28029, Madrid, Spain.|Network Collaborative Research in Tropical Diseases, RICET, Madrid, Spain.
authors.forename: Agustín
authors.initials: A
authors.lastname: Benito
mesh_terms: D000962:Antimalarials / Q000494:pharmacology*; D003430:Cross-Sectional Studies; D004094:Dihydropteroate Synthase / Q000235:genetics*; D004338:Drug Combinations; D004351:Drug Resistance; D016703:Equatorial Guinea; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D026901:Membrane Transport Proteins / Q000235:genetics*; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics*; D009154:Mutation; D010963:Plasmodium falciparum / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification; D015800:Protozoan Proteins / Q000235:genetics*; D011739:Pyrimethamine / Q000494:pharmacology; D013413:Sulfadoxine / Q000494:pharmacology; D013762:Tetrahydrofolate Dehydrogenase / Q000235:genetics*
chemical_list: D000962:Antimalarials; D004094:Dihydropteroate Synthase; D004338:Drug Combinations; D026901:Membrane Transport Proteins; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D015800:Protozoan Proteins; D011739:Pyrimethamine; D013413:Sulfadoxine; D013762:Tetrahydrofolate Dehydrogenase; C513498:Mdr1 protein, Plasmodium falciparum; C416369:PfCRT protein, Plasmodium falciparum; C001205:fanasil, pyrimethamine drug combination
keywords: Antimalarial drugs; Equatorial Guinea; Malaria; Mutations; P. falciparum; Resistance