Mario Vargas

House dust mites from the Metropolitan area of San José, Costa Rica

ABSTRACT House dust samples were collected from 60 houses around San Jose, Costa Rica. A total of 9119 mites, belonging to 14 families, 20 genera and 20 species (of which 14 are identified to species level) are reported. The relative abundance and frequency of the mites collected is also included.

Preferencias alimentarias de Triatoma dimidiata (Hemiptera: Reduvíidae) procedente de la meseta central de Costa Rica a finales del siglo XX

RESUMEN Se colectaron 267 ejemplares de Triatoma dimidiata procedentes de comunidades costarricenses ubicadas en tres regiones epidemiologicamente importantes por la Enfermedad de Chagas. A partir de cada insecto, se prepararon extractos de contenido intestinal los cuales fueron utilizados para determinar la presencia de sangres de diferentes vertebrados en un sistema de doble inmunodifusion (Outcherlony). Tambien los insectos fueron sometidos a un analisis de contenido fecal para determinar la posible infeccion con T. cruzi. El 67% de las muestras fue positiva por sangre de humano, lo que constituyo la fuente de alimentacion mas importante (p < 0,05). Tambien fue notable la presencia de sangre de perro en los vectores analizados (49,8%). Las sangres de rata, raton, didelfidos y gallinas se encontraron en porcentajes menores al 15,0%. A pesar de que no se pudo observar una ornitofila manifiesta, cuando las preferencias alimentarias fueron organizadas como cate-gorias exhaustivas y mutuamente excluyentes, la sangre de gallina constituyo la segunda categoria en frecuencia lo que denota que los triatominos pueden utilizar este sustrato alimenticio cuando la sangre humana y canina no estan disponibles. Los porcentajes de infeccion por T. cruzi fueron altamente positivos en los insectos positivos por sangres de didelfidos y ratones, lo que sugiere el papel que estos animales podrian jugar con reservorios silvestres y domicilios de T. cruzi.

Molecular and epidemiologic findings of childhood acute leukemia in Costa Rica.

In Central America, nearly 70% of pediatric cancer is related to hemato-oncologic disorders, especially acute lymphoblastic leukemia (ALL). Preliminary studies have described a high incidence of childhood leukemia in these countries; however, no molecular analyses of these malignancies have yet been carried out. We studied diagnostic samples from 84 patients from the National Childrens Hospital in San Jose, Costa Rica (65 precursor B-ALL, 5 T-cell ALL, and 14 acute myeloblastic leukemia). Our methodology included cytogenetic, fluorescent in situ hybridization, and polymerase chain reaction approaches. The observed rate of leukemia was 52.2 cases per million children per year. Twelve out of 65 (18.4%) precursor B-ALL tested positive for TEL-AML1 and 3 cases for BCR-ABL (4.6%). In addition, we detected 2 patients carrying an E2A-PBX1 transcript (3.1%) and 1 patient with an MLL-AF4 fusion gene (1.5%). None of the T-cell ALL cases were positive for either SIL-TAL1 or HOX11L2. Within 14 acute myeloblastic leukemia patients, we confirmed 2 cases with FLT3-internal tandem duplication+, 1 patient with AML1-ETO, and only 1 case carrying a PML-RARα rearrangement. The present study confirms the relatively high incidence of pediatric leukemia in Costa Rica and constitutes the first report regarding the incidence of the main molecular alterations of childhood leukemia in our region.

Variaciones biológicas de Trypanosoma cruzi (Kinetoplastida:Trypanosomatidae) asociadas con la ingestión de diferentes tipos de sangre por el vector Triatoma dimidiata (Hemiptera: Reduviidae)

The effect of avian and mouse blood in the gut of Triatoma dimidiata (Hemiptera: Reduviidae) on the biological characteristics of two costarican strains of T. cruzi (TC-2 and TC-4) was evaluated in a murine model. This relationship defined four experimental systems named TC-2 gallina, TC-2 raton, TC-4 gallina and TC-4 raton. Parasites from each system were inoculated intraperitonealy in C 3 H mice and the course of the infections were observed three times a week during 60 days. The observations included parasitemia levels (parasites/mm 3 ), concentration of slender and broad forms, duration of prepatent and patent periods, survival, and cumulated mortality. The infection characteristics in all the systems were similar with parasitemia peaks in the days 23 to 33 post infection and broad forms as the predominant tripomastigote circulating forms in all the systems. Some variables such as prepatent and patent periods did not show statistically significant differences (p < 0.05). However, the survival was prolonged in mice that were infected to parasites associated to avian blood. The evolution of the mortality was slower in these systems. The data suggests that the parasite virulence modulation could be related to the particular blood sources in the vectors.

A modified “heat escape” technique for collecting house dust mites

Abstract A new modified technique for collecting house dust mites is described. This technique was found to be better than other techniques described before.