RESUMEN
BACKGROUND: Malaria remains a major public health problem, due largely to emergence and widespread P. falciparum drug resistance. WHO recommends artemisinine combination based therapy (ACT) to overcome P. falciparum drug resistance, but reports of declining ACT efficacy have been published. A thorough understanding of the molecular bases of P. falciparum resistance to existing drugs is therefore needed. The aims of this study were to analyze the in vitro sensitivity of P. falciparum field isolates from Franceville, Gabon, to chloroquine (CQ), mefloquine (MF), dihydroartemisinine (DHA) and monodesethylamodiaquine (MDAQ), and to investigate polymorphisms associated with drug resistance. METHODS: We conducted a cross-sectional study of 53 field isolates. Field isolates sensitivity to CQ, MF, DHA and MDAQ was assessed using the colorimetric DELI test. The Pfmdr1 codons 86 and 1246, Pfcrt (haplotype codon 72 to 76) and the PfATPAse6 codons 110 and 2694 were analysed by PCR-RFLP. Associations between drug sensitivity and parasite gene polymorphisms were evaluated with the Chi square test, and routine hematological parameters were analyzed with Fisher's exact test implemented with Epinfo software. In all statistical tests, significance was assumed at p<0.05. RESULTS: A total of 46 P. falciparum isolates were successfully cultured in vitro and their sensitivity was tested. The proportions of isolates resistant to CQ, MF and MDAQ were 43.5%, 23.4% and 56.5%, respectively. Some isolates (23.9%) had DHA IC50 values higher than 10 nM. The median IC50 values were 71.67 (interquartile range (IQR, 1-438.2), 6.59 (IQR, 0.08-96), 64.79 (IQR, 0.09-448) and 6.45 nM (IQR, 0.09-23) for CQ, MF, MDAQ and DHA, respectively. The strongest correlation between diminished DHA sensitivity and MF resistance was observed (r2=0.73), followed by correlation between diminished DHA sensitivity and CQ resistance. Cross-resistance between CQ and MF was also observed. The prevalence of the 86Y and 1246Y mutations in Pfmdr1, 76T in Pfcrt, and 110A and 2694T in PfATPase6 was respectively 42% and 17.1%, 97.8%, and 0% and 22.2%. CONCLUSION: These high levels of antimalarial drug resistance in Franceville, Gabon, call for reinforced surveillance of drug efficacy.
Asunto(s)
Antimaláricos/farmacología , Resistencia a Medicamentos , Malaria Falciparum/parasitología , Plasmodium falciparum/efectos de los fármacos , Plasmodium falciparum/genética , Polimorfismo Genético , Animales , Niño , Preescolar , Estudios Transversales , Femenino , Gabón , Humanos , Lactante , Masculino , Pruebas de Sensibilidad Parasitaria , Plasmodium falciparum/aislamiento & purificación , Reacción en Cadena de la Polimerasa , Polimorfismo de Longitud del Fragmento de RestricciónRESUMEN
BACKGROUND: Malaria remains a major public health problem, especially in tropical and subtropical regions because of the emergence and widespread of antimalarial drug resistance. Traditional medicine represents one potential source of new treatments. Here, we investigated the in vitro antiplasmodial activity of bark extracts from two Fabaceae species (Tetrapleura tertaptera and Copaifera religiosa) traditionally used to treat malaria symptoms in Haut-Ogooué province, Gabon. FINDINGS: The antiplasmodial activity of dichloromethane and methanolic extracts was tested on P. falciparum strains FCB (chloroquine-resistant) and 3D7 (chloroquine-sensitive) and on fresh clinical isolates, using the DELI method. Host cell toxicity was analyzed on MRC-5 human diploid embryonic lung cells using the MTT test.The dichloromethane extracts of the two plants had interesting activity (IC50 between 8.5 ± 4.7 and 13.4 ± 3.6 µg/ml). The methanolic extract of Tetrapleura tetraptera was less active (IC50 around 30 µg/ml) and the methanolic extract of Copaifera religiosa was inactive. The selectivity index (toxicity/antiplasmodial activity) of the dichloromethane extract of Tetrapleura tetraptera was high (around 7), while the dichloromethane extract of Copaifera religiosa had the lowest selectivity (0.6). The mean IC50 values for field isolates were less than 1.5 µg/ml for dichloromethane extracts of both plants, while methanolic extracts of Tetrapleura tetraptera showed interesting activity (IC50 = 13.1 µg/ml). The methanolic extract of Copaifera religiosa was also inactive on field isolates. CONCLUSIONS: Dichloromethane extracts of Tetrapleura tetraptera and Copaifera religiosa, two plants used to treat malaria in Gabon, had interesting antiplasmodial activity in vitro. These data provide a scientific rationale for the traditional use of these plants against malaria symptoms. Bioactivity-guided phytochemical analyses are underway to identify the active compounds.
RESUMEN
Despite global antimalarial measures, Plasmodium falciparum malaria remains a major public health problem. WHO has recommended the use of arteminisin-based combination therapy to limit the emergence of antimalarial drug resistance. However, ACT treatment failures have been linked to the selection of the wild types 86N genotype of P. falciparum multidrug resistance 1 (Pfmdr1) and the 76K genotype of P. falciparum chloroquine resistance (Pfcrt) genes. The aim of this study was to investigate the molecular impact of widespread implementation of artemether-lumefantrine and artesunate-mefloquine on local parasite population in Franceville, Gabon. We analyzed 230 pediatric field isolates (96 from 2004 and 134 from 2009). Routine hematological parameters were collected. Pfmdr1 codons 86 and 1246 and Pfcrt codon 76 were genotyped using PCR-RFLP and the prevalence of the genotypes was compared. The children's mean age did not differ between 2004 and 2009 (respectively 31.8 (6-84) months vs 38.6 (6-84) months, p=0.32), and neither did mean parasitemia [16,750 (1000-96,234) and 14,587 (1093-83,941) parasites/µL, respectively (p=0.21)]. The mean hemoglobin level was higher in 2009 than in 2004 (11.0 ± 2.4 vs 7.8 ± 2.0 g/dL, respectively; p=0.04). More interesting, the prevalence of Pfmdr1 wild type 86N increased from 15.6% (n=15/96) in 2004 to 31.3% (n=42/134) in 2009 (p=0.007). A significant increase combining pure and mixed genotypes (86N+86N/Y) was also found between 2004 and 2009 (p=0.02), while the prevalence of genotypes Pfmdr1 1246D, Pfcrt wild type 76T and all mixed genotypes (Pfmdr1 86N/Y and 1246D/Y, and 76K/T) remained stable. The complexity of isolates was high (around 2.9 and 2.4) and the FC27 allele of Pfmsp2 was more prevalent. These findings show a substantial benefice of artemether-lumefantrine and artesunate-mefloquine and of new control measures. The selection, in the general population, of wild type Pfmdr1 86N, which is associated with antiplasmodial resistance against some drugs, has been induced underlining the need for molecular surveillance of the impact of ACT on antimalarial resistance.
Asunto(s)
Artemisininas/uso terapéutico , Etanolaminas/uso terapéutico , Fluorenos/uso terapéutico , Malaria Falciparum/tratamiento farmacológico , Malaria Falciparum/parasitología , Mefloquina/uso terapéutico , Proteínas Asociadas a Resistencia a Múltiples Medicamentos/genética , Plasmodium falciparum/genética , Antimaláricos/farmacología , Antimaláricos/uso terapéutico , Combinación Arteméter y Lumefantrina , Artemisininas/farmacología , Artesunato , Niño , Preescolar , Cloroquina/farmacología , Cloroquina/uso terapéutico , Combinación de Medicamentos , Resistencia a Medicamentos , Quimioterapia Combinada , Etanolaminas/farmacología , Femenino , Fluorenos/farmacología , Gabón , Genotipo , Humanos , Lactante , Malaria Falciparum/epidemiología , Masculino , Mefloquina/farmacología , Proteínas de Transporte de Membrana/genética , Parasitemia/tratamiento farmacológico , Parasitemia/epidemiología , Plasmodium falciparum/clasificación , Plasmodium falciparum/aislamiento & purificación , Polimorfismo Genético , Prevalencia , Proteínas Protozoarias/genéticaRESUMEN
AIM OF THE STUDY: As part of a project to identify new compounds active on malarial parasites, we tested the in vitro antiplasmodial activity of nine plants traditionally used to treat malaria symptoms in Haut-Ogooué Province, South-East Gabon. MATERIALS AND METHODS: Dichloromethane and methanolic extracts of each plant were tested for their antiplasmodial activity on two chloroquine-resistant strains of Plasmodium falciparum (FCB and W2), based on lactate dehydrogenase activity. Cytotoxicity was assessed with the MTT test on MRC-5 human diploid embryonic lung cells. RESULTS: The methanolic extract of Staudtia gabonensis and the dichloromethane extract of Adhatoda latibracteata showed high antiplasmodial activity (IC50<1 µg/ml) and low cytotoxicity, with selectivity indexes of about 58.25 and 16.43, respectively. The methanolic extract of Monodora myristica and the dichloromethane extract of Afromomum giganteum also showed promising activity (1Asunto(s)
Supervivencia Celular/efectos de los fármacos
, Malaria/tratamiento farmacológico
, Medicinas Tradicionales Africanas
, Extractos Vegetales/uso terapéutico
, Plantas Medicinales/química
, Gabón
, Humanos
, Extractos Vegetales/farmacología
, Plasmodium falciparum/efectos de los fármacos
, Especificidad de la Especie
RESUMEN
Despite progress in the control of malaria, it remains a serious public health problem. Substantial declines in malaria transmission, morbidity and mortality have nonetheless been reported in several countries where new malaria control strategies have been implemented. We conducted this molecular and epidemiological analysis of malaria in the pediatric department of the Chinese-Gabon Friendship Hospital (HCGC) in Franceville in 2010. Franceville is the third largest town in Gabon, and malaria transmission is high year-round. We included 945 children, 756 of them febrile. Malaria was diagnosed based on the detection of P. falciparum in thick blood films, with Lambarene's method. Malaria prevalence among the febrile children included in this study was 17.9% (n=135). The burden of malaria is thus lower than in the past; it is now the second leading cause of pediatric hospital visits, rather than the leading cause as it was in 2004. The children's mean age was 48.5 ± 3.9 months, older than in 2004 (p<0.05). We also analysed the molecular drug resistance marker, Pfmdr1. The prevalence of the wild-type genotype N86 of Pfmdr1 was 47.4% (n=64), higher than in 2004 (p<0.001). The increased prevalence of codon 1246 was not significant. Socio-economic factors and known malaria risk factors were analysed. We found that the use of Insecticide-treated mosquito nets and the provision of information (education or communication) to parents and guardians about malaria were protective factors against the disease. In conclusion, a larger study of the entire region over a longer period is necessary to characterise malaria in Franceville today. Transmission factors must also be studied.