RESUMEN
In the Amazon basin, indigenous forest-dwelling communities typically suffer from a high burden of infectious diseases, including malaria. Difficulties in accessing these isolated ethnic groups, such as the semi-nomadic Yanomami, make official malaria data largely underestimated. In the current study, we longitudinally surveyed microscopic and submicroscopic malaria infection in four Yanomami villages of the Marari community in the northern-most region of the Brazilian Amazon. Malaria parasite species-specific PCR-based detection of ribosomal and non-ribosomal targets showed that approximately 75% to 80% of all malaria infections were submicroscopic, with the ratio of submicroscopic to microscopic infection remaining stable over the 4-month follow-up period. Although the prevalence of malaria infection fluctuated over time, microscopically-detectable parasitemia was only found in children and adolescents, presumably reflecting their higher susceptibility to malaria infection. As well as temporal variation, the prevalence of malaria infection differed significantly between villages (from 1% to 19%), demonstrating a marked heterogeneity at micro-scales. Over the study period, Plasmodium vivax was the most commonly detected malaria parasite species, followed by P. malariae, and much less frequently P. falciparum. Consecutive blood samples from 859 out of the 981 studied Yanomami showed that malaria parasites were detected in only 8% of the previously malaria-positive individuals, with most of them young children (median age 3 yrs). Overall, our results show that molecular tools are more sensitive for the identification of malaria infection among the Yanomami, which is characterized by heterogeneous transmission, a predominance of low-density infections, circulation of multiple malaria parasite species, and a higher susceptibility in young children. Our findings are important for the design and implementation of the new strategic interventions that will be required for the elimination of malaria from isolated indigenous populations in Latin America.
Asunto(s)
Malaria/diagnóstico , Adolescente , Adulto , Anciano , Brasil/epidemiología , Niño , Preescolar , Estudios Transversales , ADN Protozoario/aislamiento & purificación , ADN Protozoario/metabolismo , Femenino , Humanos , Lactante , Malaria/epidemiología , Malaria/parasitología , Malaria/transmisión , Masculino , Persona de Mediana Edad , Plasmodium falciparum/genética , Plasmodium falciparum/aislamiento & purificación , Plasmodium vivax/genética , Plasmodium vivax/aislamiento & purificación , Prevalencia , Estudios Prospectivos , ARN Ribosómico 18S/genética , ARN Ribosómico 18S/metabolismo , Adulto JovenRESUMEN
In this paper, the overall morphological differences between populations of Simulium subpallidum Lutz, 1909 are studied. Several studies found in the literature point to a relationship between the labral fans and body size and the habitat where blackfly larvae occur. However, other characteristics potentially related to the microhabitat, such as abdominal hook circlet morphology, which is used for larvae to fix themselves in the substratum, and thoracic prolegs morphology, which help larvae move in the substratum, were analyzed in three different populations of S. subpallidum, one of which occupied a faster flow. The results suggest phenotypic plasticity in S. subpallidum and a tendency toward larger structures in faster flows.