RESUMEN
New diagnostic tests are needed to facilitate the diagnosis of Plasmodium falciparum malaria in the returned traveler. We performed a blinded evaluation of a nonisotopic colorimetric PCR-based assay (Digene SHARP Signal System) and compared the results with those obtained by microscopy and nested PCR for the detection of P. falciparum malaria in 150 febrile travelers. By using nested PCR as the reference standard, the colorimetric assay had a sensitivity of 100% and a specificity of 95.4% for the detection of P. falciparum. This PCR-based nonisotopic assay is a rapid, sensitive, and specific method for the detection of falciparum malaria in returned travelers.
Asunto(s)
Malaria Falciparum/diagnóstico , Plasmodium falciparum/aislamiento & purificación , Reacción en Cadena de la Polimerasa/métodos , Adolescente , Anciano , Anciano de 80 o más Años , Animales , Niño , Preescolar , Colorimetría , Estudios de Evaluación como Asunto , Femenino , Fiebre/parasitología , Humanos , Lactante , Malaria Falciparum/parasitología , Masculino , Microscopía , Persona de Mediana Edad , Plasmodium falciparum/genética , Sensibilidad y Especificidad , ViajeRESUMEN
Chloroquine-resistant Plasmodium falciparum is well documented in Thailand. Laos, however, continues to use chloroquine (CQ) as the first-line therapy for the treatment of P. falciparum malaria. The objective of the present study was to determine the prevalence, in these two areas, of the cg2, pfmdr1 and pfcrt allelic types that have previously been associated with CQ resistance. Isolates of P. falciparum were collected from participants in ongoing treatment studies conducted in Thailand (near the Thai-Cambodian border) and in Laos (Vang Vieng district). The pfmdr1 and pfcrt alleles were characterized by PCR-RFLP and mutations in cg2 were characterized by PCR and single-stranded-conformation-polymorphism (SSCP) electrophoresis. Eight (32%) of the 25 Laotian isolates but only one (4%) of the 25 Thai isolates were found to contain the pfmdr1 mutation N86Y (P = 0.02). In contrast, the cg2 polymorphisms previously associated with CQ resistance were present in only 10 of the isolates from Laos but 24 of those from Thailand (40% v. 96%; P < 0.001). All the samples from both countries contained the pfcrt K76T mutant allele reported to confer resistance to CQ. The results may indicate that drug pressure for the maintenance of the pfmdr1 and cg2 alleles varies in intensity in the Thai and Laotian study areas, probably reflecting differences in the national malaria-treatment policies of Thailand and Laos.
Asunto(s)
Transportadoras de Casetes de Unión a ATP , Antimaláricos/farmacología , Cloroquina/farmacología , Malaria Falciparum/parasitología , Plasmodium falciparum/efectos de los fármacos , Plasmodium falciparum/genética , Animales , Resistencia a Medicamentos/genética , Marcadores Genéticos , Humanos , Laos , Malaria Falciparum/tratamiento farmacológico , Mutación , Reacción en Cadena de la Polimerasa/métodos , Proteínas Protozoarias/genética , TailandiaRESUMEN
We compared two collection devices, IsoCode and FTA, with whole blood for the diagnosis of malaria by PCR (n = 100). Using whole blood as the reference standard, both devices were sensitive for the detection of single-species malaria infections by PCR (> or =96%). However, the detection of mixed infections was suboptimal (IsoCode was 42% sensitive, and FTA was 63% sensitive).