RESUMEN

The human malaria parasite Plasmodium falciparum is globally widespread, but its prevalence varies significantly between and even within countries. Most population genetic studies in P. falciparum focus on regions of high transmission where parasite populations are large and genetically diverse, such as sub-Saharan Africa. Understanding population dynamics in low transmission settings, however, is of particular importance as these are often where drug resistance first evolves. Here, we use the Pacific Coast of Colombia and Ecuador as a model for understanding the population structure and evolution of Plasmodium parasites in small populations harboring less genetic diversity. The combination of low transmission and a high proportion of monoclonal infections means there are few outcrossing events and clonal lineages persist for long periods of time. Yet despite this, the population is evolutionarily labile and has successfully adapted to changes in drug regime. Using newly sequenced whole genomes, we measure relatedness between 166 parasites, calculated as identity by descent (IBD), and find 17 distinct but highly related clonal lineages, six of which have persisted in the region for at least a decade. This inbred population structure is captured in more detail with IBD than with other common population structure analyses like PCA, ADMIXTURE, and distance-based trees. We additionally use patterns of intra-chromosomal IBD and an analysis of haplotypic variation to explore past selection events in the region. Two genes associated with chloroquine resistance, crt and aat1, show evidence of hard selective sweeps, while selection appears soft and/or incomplete at three other key resistance loci (dhps, mdr1, and dhfr). Overall, this work highlights the strength of IBD analyses for studying parasite population structure and resistance evolution in regions of low transmission, and emphasizes that drug resistance can evolve and spread in small populations, as will occur in any region nearing malaria elimination.

Asunto(s)

Antimaláricos , Malaria Falciparum , Parásitos , Animales , Humanos , Plasmodium falciparum/genética , Antimaláricos/farmacología , Antimaláricos/uso terapéutico , Malaria Falciparum/tratamiento farmacológico , Malaria Falciparum/epidemiología , Malaria Falciparum/parasitología , Cloroquina/uso terapéutico , Resistencia a Medicamentos/genética , América del Sur/epidemiología

RESUMEN

As malaria control programmes concentrate their efforts towards malaria elimination a better understanding of malaria transmission patterns at fine spatial resolution units becomes necessary. Defining spatial units that consider transmission heterogeneity, human movement and migration will help to set up achievable malaria elimination milestones and guide the creation of efficient operational administrative control units. Using a combination of genetic and epidemiological data we defined a malaria transmission unit as the area contributing 95% of malaria cases diagnosed at the catchment facility located in the town of Guapi in the South Pacific Coast of Colombia. We provide data showing that P. falciparum malaria transmission is heterogeneous in time and space and analysed, using topological data analysis, the spatial connectivity, at the micro epidemiological level, between parasite populations circulating within the unit. To illustrate the necessity to evaluate the efficacy of malaria control measures within the transmission unit in order to increase the efficiency of the malaria control effort, we provide information on the size of the asymptomatic reservoir, the nature of parasite genotypes associated with drug resistance as well as the frequency of the Pfhrp2/3 deletion associated with false negatives when using Rapid Diagnostic Tests.

Asunto(s)

Antígenos de Protozoos/genética , Resistencia a Medicamentos/genética , Eliminación de Gen , Malaria Falciparum , Plasmodium falciparum , Proteínas Protozoarias/genética , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Colombia/epidemiología , Femenino , Humanos , Lactante , Malaria Falciparum/tratamiento farmacológico , Malaria Falciparum/epidemiología , Malaria Falciparum/genética , Malaria Falciparum/transmisión , Masculino , Persona de Mediana Edad , Plasmodium falciparum/genética , Plasmodium falciparum/patogenicidad

RESUMEN

BACKGROUND: Entamoeba histolytica and Entamoeba dispar are morphologically identical. However, the former is highly pathogenic and the latter is not. AIM: To differentiate Entamoeba histolytica from Entamoeba dispar through ELISA and PCR techniques in Colombian isolates from feces. MATERIAL AND METHODS: Descriptive study of Colombian fecal samples from 53 males and 47 women, that were positive for the complex E. histolytica/E. dispar on light microscopy. Positive samples were cultured on Robinson medium to isolate trophozoites. The presence of specific Gal/ GalNAc-lectin was determined by ELISA and polymerase chain reaction in genomic DNA, using the combination of three nucleotides that recognize a variable region of 16S small subunit ribosomal RNA, generating a 166 base pair (bp) product for E. histolytica and 752 pb product for E. dispar. RESULTS: After verification, only eight of the 100 samples were positive for the complex E. histolytica/E. dispar and were cultivated. Isolates were obtained in six cultures, one corresponded to E. histolytica and six to E. dispar. CONCLUSIONS: The presence of E. histolytica/E. dispar complex was largely overestimated with light microscopy. In the few samples where isolates were obtained, the technique described differentiated between both strains.

Asunto(s)

Entamoeba/metabolismo , Entamebiasis/parasitología , Colombia , ADN Protozoario/genética , Entamoeba/genética , Entamoeba/aislamiento & purificación , Entamoeba histolytica/genética , Entamoeba histolytica/aislamiento & purificación , Entamebiasis/diagnóstico , Ensayo de Inmunoadsorción Enzimática , Heces/parasitología , Femenino , Humanos , Lectinas , Masculino , Reacción en Cadena de la Polimerasa/métodos , Proteínas Protozoarias , ARN Ribosómico 16S/genética , Sensibilidad y Especificidad

RESUMEN

Background: Entamoeba histolytica and Entamoeba dispar are morphologically identical. However, the former is highly pathogenic and the latter is not. Aim: To differentiate Entamoeba histolytica from Entamoeba dispar through ELISA and PCR techniques in Colombian isolates from feces. Material and Methods: Descriptive study of Colombian fecal samples from 53 males and 47 women, that were positive for the complex E. histolytica/E. dispar on light microscopy. Positive samples were cultured on Robinson medium to isolate trophozoites. The presence of specific Gal/ GalNAc-lectin was determined by ELISA and polymerase chain reaction in genomic DNA, using the combination of three nucleotides that recognize a variable region of 16S small subunit ribosomal RNA, generating a 166 base pair (bp) product for E. histolytica and 752 pb product for E. dispar. Results: After verification, only eight of the 100 samples were positive for the complex E. histolytica/E. dispar and were cultivated. Isolates were obtained in six cultures, one corresponded to E. histolytica and six to E. dispar. Conclusions: The presence of E. histolytica/E. dispar complex was largely overestimated with light microscopy. In the few samples where isolates were obtained, the technique described differentiated between both strains.

Asunto(s)

Femenino , Humanos , Masculino , Entamoeba/metabolismo , Entamebiasis/parasitología , Colombia , ADN Protozoario/genética , Entamoeba histolytica/genética , Entamoeba histolytica/aislamiento & purificación , Entamoeba/genética , Entamoeba/aislamiento & purificación , Entamebiasis/diagnóstico , Ensayo de Inmunoadsorción Enzimática , Heces/parasitología , Lectinas , Reacción en Cadena de la Polimerasa/métodos , Proteínas Protozoarias , /genética , Sensibilidad y Especificidad

RESUMEN

Latin America contributes 1-1.2 million clinical malaria cases to the global malaria burden of about 300 million per year. In 21 malaria endemic countries, the population at risk in this region represents less than 10% of the total population exposed worldwide. Factors such as rapid deforestation, inadequate agricultural practices, climate change, political instability, and both increasing parasite drug resistance and vector resistance to insecticides contribute to malaria transmission. Recently, several malaria endemic countries have experienced a significant reduction in numbers of malaria cases. This is most likely due to actions taken by National Malaria Control Programs (NMCP) with the support from international funding agencies. We describe here the research strategies and activities to be undertaken by the Centro Latino Americano de Investigación en Malaria (CLAIM), a new research center established for the non-Amazonian region of Latin America by the National Institute of Allergy and Infectious Diseases (NIAID). Throughout a network of countries in the region, initially including Colombia, Guatemala, Panama, and Peru, CLAIM will address major gaps in our understanding of changing malaria epidemiology, vector biology and control, and clinical malaria mainly due to Plasmodium vivax. In close partnership with NMCPs, CLAIM seeks to conduct research on how and why malaria is decreasing in many countries of the region as a basis for developing and implementing new strategies that will accelerate malaria elimination.

Asunto(s)

Erradicación de la Enfermedad/métodos , Erradicación de la Enfermedad/organización & administración , Diseño de Investigaciones Epidemiológicas , Malaria/prevención & control , Animales , Atención a la Salud/organización & administración , Resistencia a Medicamentos , Variación Genética , Humanos , Imidazoles/farmacología , Insectos Vectores/parasitología , Insectos Vectores/fisiología , Cooperación Internacional , América Latina/epidemiología , Malaria/epidemiología , Malaria/inmunología , Malaria/parasitología , Vacunas contra la Malaria/administración & dosificación , Vacunas contra la Malaria/inmunología , Programas Nacionales de Salud/organización & administración , Niacina/análogos & derivados , Niacina/farmacología , Plasmodium/efectos de los fármacos , Plasmodium/genética , Plasmodium/inmunología , Plasmodium/patogenicidad , Factores Socioeconómicos

RESUMEN

The therapeutic efficacy of sulfadoxine-pyrimethamine (SP) in treating uncomplicated Plasmodium falciparum malaria is unevenly distributed in Colombia. The Andes mountain range separates regions in the west where malaria is endemic from those in the east and constitutes a barrier against gene flow and the dispersal of parasite populations. The distribution of dhfr and dhps genotypes of 146 P. falciparum samples from the eastern Amazon and Orinoco basins and Northwest and Southwest Pacific regions of Colombia was consistent with the documented levels of therapeutic efficacy of SP. The diversity of four dhfr- and dhps-linked microsatellites indicated that double- and triple-mutant alleles for both resistance loci have a single origin. Likewise, multilocus association genotypes, including two unlinked microsatellite loci, suggested that genetic exchanges between the eastern Orinoco and Northwest Pacific populations has taken place across the Andes, most probably via migration of infected people.

Asunto(s)

Antimaláricos/farmacología , Resistencia a Medicamentos/genética , Emigración e Inmigración , Malaria Falciparum/transmisión , Plasmodium falciparum/efectos de los fármacos , Pirimetamina/farmacología , Sulfadoxina/farmacología , Alelos , Animales , Antimaláricos/uso terapéutico , Colombia/epidemiología , Dihidropteroato Sintasa/genética , Combinación de Medicamentos , Frecuencia de los Genes , Genotipo , Humanos , Malaria Falciparum/tratamiento farmacológico , Malaria Falciparum/epidemiología , Malaria Falciparum/parasitología , Repeticiones de Microsatélite , Datos de Secuencia Molecular , Pruebas de Sensibilidad Parasitaria , Plasmodium falciparum/genética , Pirimetamina/uso terapéutico , Análisis de Secuencia de ADN , Sulfadoxina/uso terapéutico , Tetrahidrofolato Deshidrogenasa/genética

RESUMEN

Plasmodium vivax and Plasmodium falciparum are the two prevalent human malaria species. A Colombian P. vivax wild strain has been adapted in Aotus nancymaae monkeys for use in further biological and immunological studies. We present data validating a real-time PCR assay quantifying P. vivax parasitemia, using the small subunit ribosomal RNA genes as an amplification target. P. vivax species-specific primers were designed on the 18S ribosomal gene V8 region, for amplifying both asexual and sporozoite ssrRNA genes. The assay detects amplification products bound to fluorescent SYBR-Green I dye using Perkin-Elmer GeneAmp-5700-SDS. Linear range standard curves from 6 DNA concentration logs (+0.99 correlation coefficients) were obtained. Standard curves were constructed using a plasmid containing target gene for real-time PCR amplification. This P. vivax specific assay is very sensitive, having a three parasite detection limit, and is reproducible and accurate. It involves a "closed-tube" PCR, avoids time-consuming post-PCR manipulation, and decreases potential PCR contamination.

Asunto(s)

ADN Ribosómico/sangre , Malaria Vivax/diagnóstico , Parasitemia/diagnóstico , Plasmodium vivax/aislamiento & purificación , Reacción en Cadena de la Polimerasa/métodos , Animales , Aotidae , ADN Protozoario/sangre , Plasmodium vivax/genética , ARN Ribosómico/genética , Reproducibilidad de los Resultados , Sensibilidad y Especificidad

RESUMEN

Se informa el estudio realizado en la Cueva del Eden (Cunday, Tolima) para aislar, de las tierras de la cueva y de murcielagos alli capturados, al Histoplasma Capsulatum, como agente causal de una anterior epidemia de histoplasmosis ocurrida entre visitantes de la cueva. El agente se aislo en 8 de las 27 muestras de tierra y guano de murcielago. Se capturaron 233 ejemplares pertenecientes a 4 generos de murcielagos y en los cultivos practicados en higado, pulmon y bazo de cien de ellos, no fue posible aislar el H. Capsulatum

Asunto(s)

Animales , Quirópteros/parasitología , Histoplasmosis/transmisión , Colombia , Suelo/análisis