Paradoxical associations between soil-transmitted helminths and Plasmodium falciparum infection.

Evidence on the comorbidity between soil-transmitted helminth infections and malaria is scarce and divergent. This study explored the interactions between soil-transmitted helminth infections and uncomplicated falciparum malaria in an endemic area of Colombia. A paired case-control study matched by sex, age and location in Tierralta, Cordoba, was done between January and September 2010. The incident cases were 68 patients with falciparum malaria and 178 asymptomatic controls. A questionnaire was used to gather information on sociodemographic variables. Additionally physical examinations were carried out, stool samples were analysed for intestinal parasites and blood samples for Ig E concentrations. We found associations between infection with hookworm (OR: 4.21; 95% CI: 1.68-11.31) and Ascaris lumbricoides (OR 0.43; 95% CI: 0.18-1.04) and the occurrence of falciparum malaria. The effects of soil-transmitted helminths on the occurrence of malaria were found to be paradoxical. While hookworm is a risk factor, A. lumbricoides has a protective effect. The findings suggest that, in addition to the comorbidity, the presence of common determinants of soil-transmitted helminth infections and malaria could also exist. While the biological mechanisms involved are not clear, public health policies aimed at the control of their common social and environmental determinants are suggested.

Origin and dissemination across the Colombian Andes mountain range of sulfadoxine-pyrimethamine resistance in Plasmodium falciparum.

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.

Detección y expresión de una proteína de unión a calmodulina en Plasmodium falciparum / Detection and expression of a calmodulin binding protein from Plasmodium falciparum

Se produjo un anticuerpo monoclonal a partir de proteínas de unión a calmodulina (PUCaM) aislada por cromatografía de afinidad. Utilizando el inmunoensayo Western blot se detectó una proteína de 30 kDa en extractos de glóbulos rojos parasitados con Plasmodium falciparum. Esta señal no se observó en extractos de eritrocitos no infectados. Adicionalmente, este anticuerpo presentó una reacción con dos bandas de alto peso molecular localizadas en 260 y 240 kDa, siendo mucho más intensa la señal para 240 kDa. Estas mismas bandas fueron reconocidas por un anticuerpo policlonal anti-espectrina. Lo anterior implica que el anticuerpo monoclonal 1G3 presenta una reacción cruzada con las cadenas de la espectrina y sugiere la presencia de un epítope similar a una estructura estrechamente relacionada en ambas proteínas. Se estudió la expresión de esta proteína durante el ciclo de desarrollo del parásito y se pudo definir su presencia en las fases tardías del ciclo. L cantidad de la PUCaM de 30 kDa no sólo aumenta de manera absoluta, sino también relativamente con relación a las demás proteínas del parásito. El hecho de que se presente señal en los estadios avanzados de desarrollo y no en el estadio de anillos está indicando que tiene un patrón de expresión diferencial durante el desarrollo del parásito