Sympatry influence in the interaction of Trypanosoma cruzi with triatomine

Abstract INTRODUCTION: Trypanosoma cruzi, the etiologic agent of Chagas disease, is widely distributed in nature, circulating between triatomine bugs and sylvatic mammals, and has large genetic diversity. Both the vector species and the genetic lineages of T. cruzi present a varied geographical distribution. This study aimed to verify the influence of sympatry in the interaction of T. cruzi with triatomines. Methods: The behavior of the strains PR2256 (T. cruzi II) and AM14 (T. cruzi IV) was studied in Triatoma sordida (TS) and Rhodnius robustus (RR). Eleven fifth-stage nymphs were fed by artificial xenodiagnosis with 5.6 × 103 blood trypomastigotes/0.1mL of each T. cruzi strain. Every 20 days, their excreta were examined for up to 100 days, and every 30 days, the intestinal content was examined for up to 120 days, by parasitological (fresh examination and differential count with Giemsa-stained smears) and molecular (PCR) methods. Rates of infectivity, metacyclogenesis and mortality, and mean number of parasites per insect and of excreted parasites were determined. RESULTS: Sympatric groups RR+AM14 and TS+PR2256 showed higher values of the four parameters, except for mortality rate, which was higher (27.3%) in the TS+AM14 group. General infectivity was 72.7%, which was mainly proven by PCR, showing the following decreasing order: RR+AM14 (100%), TS+PR2256 (81.8%), RR+PR2256 (72.7%) and TS+AM14 (36.4%). CONCLUSIONS: Our working hypothesis was confirmed once higher infectivity and vector capacity (flagellate production and elimination of infective metacyclic forms) were recorded in the groups that contained sympatric T. cruzi lineages and triatomine species.

Pulícidos: aspectos adaptativos y biológicos / Pulicides: adaptative and biological aspects

Las pulgas son insectos hematófagos que se caracterizan por una baja especificidad parasitaria. Son ectoparásitos de distintos animales y del hombre. El cuerpo de estos insectos está comprimido lateralmente y las antenas pueden replegarse dentro de un surco a los costados de la cabeza, características óptimas para un mejor desplazamiento entre los pelos y las plumas de los hospedadores. Los tres pares de patas son fuertes y poderosas, armadas con robustas espinas y en sus extremos con un par de grandes uñas en forma de garfios. El tercer par es el que está adaptado para saltar. Las piezas bucales son sucsopicadoras y modificadas en forma de estiletes. Algunas especies tienen unas hileras de cerdas (ctenidios) en la zona genal y/o en el dorso del primer segmento toráxico que evitan los movimientos de retroceso y la caída del cuerpo del hospedador. Esta característica también dificulta la extracción de los parásitos. La importancia de los pulícidos radica entre otras, por ser transmisores de la peste y el tifus. Se muestran bajo SEM y con microfotografías las adaptaciones al parasitismo, la biología y las afecciones cutáneas que se producen

Role of some medically important arthropods in home environment and childhood urticaria

Home environment does not only affect morbidity but also chronicity of certain disease of the reared children. Several medically important arthropods are of special concern, as well as domestic anima and pets. Fifty patients with popular urinary, compared to 50 normal controls, were tested with 5 types of mite antigens: acarus siro, dermatophagoides farinae, derratophagoides, pteronyssinus, clycophagus domesticus and tyrophaus putrescentiae. The skin reaction were recorded after 1/2 hours, 24 hours and 48 hours. This study revealed that popular urticaria is prevalent in children below 7 years. Both sexes were equally affected. Family history has no significant role in the disease. There was a significant relation between pets and the disease. Mites play an important role in the aetiology of popular urticaria. The most responsible mites are dermatophagiods farinae and yrophagus putrescentiae. Dermatophagoides pternoyssinus and glycophagus domesticus had no statistical significant relation to popular urticaria as tested by mite antigen skin reactions. However, there were actually more positive reaction in patients with popular utricaria than in the control groups. It is questionably advised that desensitization may be of real health for patients with popular urticaria which can be administered at an early phase of the disease. Also, environmerltal control of mites will be very helpful in suppressing and minimizing the attacks