Between July and November 2004, a survey was conducted in order to investigate the clinical and epidemiological profiles of enterobiasis in 100 preschool (2-5 years) and primary school (6-12 years) aged children, from a rural village in north western semiarid region, Falcon state, Venezuela. Symptoms associated to oxiuriasis, including anal pruritus, perianal lesions, bruxism, enuresis, as well as children behaviours (finger sucking, hand washing, etc.), were determined by means of clinical examination and anamnesis. The Graham technique (perianal swabs with an adhesive cellulose tape) was used to perform the parasitological diagnosis. The overall prevalence was high (45%). There was no difference in the prevalence between sexes (χ 2 = 0, 0016; p= 0,968) or ages (χ 2 = 0,087; p= 0,769). Anal pruritus was the most common clinical finding and the only one significantly associated with enterobiasis, being detected in 33% of in infected children and in 24% of non parasitized ones. Graffar analysis revealed that the majority of children belong to the poorer socioeconomic strata: IV (77, 6%) and V (17, 2%). The following risk factors appeared to be significantly related to transmission and endemic maintenance of enterobiasis: pet playing (OR= 3,90), overcrowding (OR= 2,4), mother's low level education (OR= 7,88) and non-potable water consuming (OR= 1,01). Aerosol, inhalation and retroinfection dissemination, instead of via handanus-mouth, should be playing a relevant role in the transmission of Enterobius vermicularis among children.

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Frequent individual observations od different stages of Rhodnius prolixus exposed to Trypanosoma rangeli, revealed a higher susceptibility to infection in the bugs exposed during the two first instars. The mortality rate in infected bugs was significantly higher than in controls, indicating that the parasite was responsible for the majority of deaths. An analysis of the mortality distribution, per instar, is presented. Statistical analysis of deaths among the different infected instars, showed that T. rangeli produces its pathological effect in any stage of R. prolixus independently of its susceptibility to the parasite. The survival to adult decreased in all the infected instar bugs. A significant longer time to reach the adult stage was observed in the infected bugs when compared with controls, excepting for specimens exposed in the third instar. The epidemiological significance of the present results is discussed.

The exploitation of new wilderness areas with crops is increasing and traditional crop substitution has been modified by new more productive crops. The results show the anthropogenic disturbance effect on the sandflies population and Leishmania transmission in endemic areas of Venezuela. Three agroecosystems with variable degrees of ecological disturbance, forest (conserved), cacao (fragmented), and orangery (disturbed), were selected. Four methods to sandfly capture were used; the specimens were identified and infected with Leishmania. Diversity, population structure, ANOVA, Tukey test, and simple correlation analysis were carried out. Shannon traps were able to capture 94.7% of the total sandflies, while CDC light traps, Sticky traps, and direct suction just captured 2.2%, 1.2%, and 0.9%, respectively. The results showed the effect of ecological disturbance degree on the composition of sandflies and population structure, revealing a dominance level increased but decreased on the diversity and richness of sandflies species in the greatest ecological disturbance area in relation to areas with less organic disturbance. Environments more disturbed cause adaptability of certain species such as Lutzomyia gomezi and Lutzomyia walkeri. These changes on the composition of sandflies population and structure emerging species could cause increasing of leishmaniasis transmission.

a cross-sectional survey was conducted to investigate clinical and epidemiological data on pinworm infection among 427 preschool and primary school age children of six rural communities from the semiarid region of Falcon state, northwestern Venezuela. Children were evaluated clinically and parasitologically by the Graham method. Overall prevalence was high (63.23 %). Pinworm infection rates were not significantly different between sex or age, suggesting similar transmission pattern and risk conditions for all individuals. Among the clinical findings and children's habits, only perianal itching, enuresis, bruxism, and finger sucking showed significant higher percentages in infected children than in uninfected. Of interest was that anal pruritus (odds ratio [OR], 2.441), finger sucking (OR, 1.901), lower socioeconomic levels (OR, 4.358) and high levels of overcrowding conditions (≥ 3 persons/room: OR, 1.878; ≥ 2 persons/bed: OR, 11.833) appeared to be significant factors associated with transmission and endemic maintenance of enterobiasis among student children in this semi-arid Venezuelan region.

As part of an epidemiological study on leishmaniasis in Merida, Venezuela, the diversity and dispersion of sandflies species found in 15 localities between 175 m and 1,960 m.a.s.l., are presented. From 7,126 collected sandflies (5,132 female and 1,994 male), 24 species were identified, 10 of them recognized as anthropophilic. The relation species-altitude is presented, and the species composition found in human dwellings, periodomestic and sylvatic areas, are recorded. The possible role of the identified species on the transmission of leishmaniasis in the andean region, is discussed.

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Multivariate discriminant analysis was employed to discriminate on a morphological basis females of 3 closely related sand fly species, Lutzomyia townsendi (Ortiz), L. spinicrassa Morales, Osorno-Mesa, Osorno & Hoyos, and L. youngi Feliciangeli & Murillo. Principal component and canonical discriminant analysis compared a set of 31 morphological characters measured from known specimens to detect differences among the 3 species. A subset of 6 characters separated the 3 species with a high level of confidence. A simple method is presented to identify an unknown specimen as L. townsendi, L. spinicrassa, or L. youngi using these 6 morphological characters.