Leishmania infantum es el agente etiológico de la leishmaniasis visceral (LV). Sin embargo, tanto en el Viejo Mundo como en el Nuevo Mundo (América Central), este protozoario ha sido involucrado en casos de leishmaniasis cutánea atípica (LCA). Evidencias clínicas, parasitológicas, moleculares y entomológicas han demostrado que una situación similar está ocurriendo en un área periurbana de Altagracia de Orituco (Guárico, Venezuela). Con la finalidad de contribuir al entendimiento de este nuevo escenario epidemiológico, se realizó un estudio transversal en el cual se determinó la reactividad a la prueba de leishmanina [Leishmanin skin test (LST)] y la seroprevalencia a antígenos crudos de Leishmania spp. y al antígeno específico rK39 mediante la prueba de ELISA en una muestra de ocho casos de LCA detectados en el periodo 1997-2000, en sus cohabitantes (n=15) y en una muestra de 233 de la comunidad igualmente expuestas a riesgo. La dermoprevalencia resultó ser de 31,6% (67/212). El 28,8% (67/233) resultó positivo a la prueba de ELISA usando promastigotas de L. infantum (=L. chagasi) y 13,3% (31/233) poseían anticuerpos anti-L. braziliensis. Así mismo, la prueba de ELISA usando el antígeno rK39 resultó positiva en uno de los ocho casos estudiados y en dos de sus cohabitantes; así como también en 13,7% (32/233) de los individuos residentes en la comunidad. Los resultados obtenidos indican la circulación de especies del subgénero Leishmania y del subgénero Viannia en el área en estudio y que la presencia de anticuerpos anti-Leishmania en general se encontró asociada a la edad y al tiempo de residencia en la zona.

Leishmania infantum is the etiological agent of the visceral leishmaniasis (VL). However, in the Old World as well in the New World (CentralAmerica), this protozoan has also been involved in cases of atypical cutaneous leishmaniasis (ACL). Clinical, molecular and entomological evidences have demonstrated that a similar situation is happening in a peri-urban area of Altagracia de Orituco (Guárico state, Venezuela). With the purpose of contributing to the understanding of such an epidemiological scenario, a cross-sectional study was carryed out using the leishmanin skin test (LST) and screening for the seroprevalence to crude antigens of Leishmania spp. and rK39 by means of the ELISA test in cases of ACL reported in the period 1997-2000 (n=8), among their co-inhabitants (n=15) and in a randomly selected sample of 233 people. The dermoprevalence was 31.6% (67/212); 28.8% (67/233) were positive to the ELISA test using promastigotes of L. infantum (= L. chagasi) and 13.3% (31/233) had antibodies anti-L. braziliensis. In addition, the test of ELISA using the antigen rK39 was positive in one out of the eight cases studied and in two out of their co-inhabitants; as well as in 13.7% (32/233) of the inhabitants of the community. The results obtained in this epidemiological study indicate the circulation of species of the sub-genus Leishmania as well as of the subgenus Viannia. The presence of antibodies anti-Leishmania in general was associated to the age and the time of residence in the zone.

A cell-free system from Plasmodium falciparum able to translate endogenous mRNA was used to determine the effect of artemisinin, chloroquine and primaquine on the protein synthesis mechanism of the parasite. The antimalarial drugs did not inhibit the incorporation of [³H] methionine into parasite proteins even at concentrations higher than the ones found to strongly inhibit the parasite growth. Results clearly indicate that these compounds do not have a direct effect on protein synthesis activity of P. falciparum coded by endogenous mRNA.

An in vitro translation system has been prepared from Plasmodium falciparum by saponin lysis of infected-erythrocytes to free parasites which were homogeneized with glass beads, centrifuged to obtain a S-30 fraction followed by Sephadex G-25 gel filtration. This treatment produced a system with very low contamination of host proteins (<1%). The system, optimized for Mg2+ and K+, translates endogenous mRNA and is active for 80 min which suggests that their protein factors and mRNA are quite stable.