Panstrongylus geniculatus es un triatomino, vector del Trypanosoma cruzi, agente etiológico de la Enfermedad de Chagas, propio de los corredores biológicos que se dan entre ciclos de transmisión ...urbano y periurbano en Venezuela. Los modelos de nicho ecológico y distribución potencial de especies permiten conocer la relación entre los factores climáticos y la presencia real de las especies. El modelo de distribución geográfica potencial para P. geniculatus, generado mediante MAXENT, mostró áreas con condiciones bioclimáticas próximas a su nicho ecológico; así, definió una amplia distribución potencial con énfasis en la zona norte costera de Venezuela (estados Lara, Yaracuy, Carabobo, Aragua, Miranda, Distrito Capital, Vargas, Monagas y Sucre) con probabilidades de media a muy altas (0,56 - 1). También predijo áreas con condiciones de idoneidad en estados occidentales y orientales a pesar de que los registros reales son escasos. La isotermalidad y temperatura máxima del mes más caliente contribuyeron en 43,4 % al establecimiento del modelo, en tanto que variables relacionadas con la precipitación, contribuyeron en 56,6 %. Esto coincide con el hecho de que los triatominos son termo-tolerantes y se distribuyen en función de la temperatura, la cual también condiciona el número de triatominos infectados. Las áreas geográficas idóneas del país serían zonas de riesgo para la infestación triatomínica y la transmisión de T. cruzi, por coincidencia con la zona de mayor densidad de la poblacional humana, lo cual requeriría afinar estrategias de vigilancia entomológica y control epidemiológico.
The increasing population of Aedes aegypti mosquitoes on Madeira Island (Portugal) resulted in the first autochthonous dengue outbreak, which occurred in October 2012. Our study establishes the first ...genetic evaluation based on the mitochondrial DNA (mtDNA) genes cytochrome oxidase subunit I (COI) and NADH dehydrogenase subunit 4 (ND4) and knockdown resistance (kdr) mutations exploring the colonisation history and the genetic diversity of this insular vector population. We included mosquito populations from Brazil and Venezuela in the analysis as putative geographic sources. The Ae. aegypti population from Madeira showed extremely low mtDNA genetic variability, with a single haplotype for COI and ND4. We also detected the presence of two important kdr mutations and the quasi-fixation of one of these mutations (F1534C). These results are consistent with a unique recent founder event that occurred on the island of Ae. aegypti mosquitoes that carry kdr mutations associated with insecticide resistance. Finally, we also report the presence of the F1534C kdr mutation in the Brazil and Venezuela populations. To our knowledge, this is the first time this mutation has been found in South American Ae. aegypti mosquitoes. Given the present risk of Ae. aegypti re-invading continental Europe from Madeira and the recent dengue outbreaks on the island, this information is important to plan surveillance and control measures.
Triatoma maculata is a wild vector of Trypanosoma cruzi, the causative agent of Chagas disease; its incursion in the domestic habitat is scant. In order to establish the possible domestic habitat of ...T. maculata, we evaluated wing variability and polymorphism of genotypic markers in subpopulations of T. maculata that live in different habitats in Venezuela. As markers, we used the mtCyt b gene, previously apply to evaluate population genetic structure in triatomine species, and the β-tubulin gene region, a marker employed to study genetic variability in Leishmania subgenera. Adults of T. maculata were captured in the period 2012-2013 at domestic, peridomestic (PD), and wild areas of towns in the Venezuelan states of Anzoátegui, Bolívar, Portuguesa, Monagas, Nueva Esparta, and Sucre. The phenotypic analysis was conducted through the determination of the isometric size and conformation of the left wing of each insect (492 individuals), using the MorphoJ program. Results reveal that insects of the domestic habitat showed significant reductions in wing size and variations in anatomical characteristics associated with flying, in relation to the PD and wild habitats. The largest variability was found in Anzoátegui and Monagas. The genotypic variability was assessed by in silico sequence comparison of the molecular markers and PCR-RFLP assays, demonstrating a marked polymorphism for the markers in insects of the domestic habitat in comparison with the other habitats. The highest polymorphism was found for the β-tubulin marker with enzymes BamHI and KpnI. Additionally, the infection rate by T. cruzi was higher in Monagas and Sucre (26.8 and 37.0%, respectively), while in domestic habitats the infestation rate was highest in Anzoátegui (22.3%). Results suggest domestic habitat colonization by T. maculata that in epidemiological terms, coupled with the presence in this habitat of nymphs of the vector, represents a high risk of transmission of Chagas disease.
One thousand and forty five scorpion-envenomed (SE) patients studied from 1990 to 1996 were analyzed. Depending on symptom intensity, these cases were distributed in categories: 1) Light Scorpion ...Envenoming (LSE) 72.06% expressed only a few symptoms like pain at the sting site: followed by 2) Moderate Scorpion Envenoming (MSE) with 16.55%,: and Intense Scorpion Envenoming with 9.95%, and finally a group of patients classified as 4) Severe Scorpion Envenoming (SSE), with 1.44%. The proportion of envenomed subjects was analysed by age group and sex. In a comparison of the percentages SE by age groups classified by the Student T-test (p < 0.05), showed no significant differences for the distribution of cases in the ages over 10 years old, but the number of cases for ages under 10 years was significant. Towns located at altitudes of over 1,000 meters had the highest scorpion envenoming indexes: San Antonio de Los Altos- Los Teques (26.2%), Baruta-Hatillo-Hoyo de la Puerta (19.8%), El Junquito (15.4%). These localities accounted for 61.4% of scorpion envenoming, while 38.6% were distributed in ten towns down 800 meters. The envenoming could occur at any moment of the day, although the highest incidence (69.3%) was between 6:00 AM and 6:00 PM. A detailed analysis of the scorpion envenoming time distribution indicated that the highest percentage (42.8%) was concentrated from 6:00 AM to 12:00 M. In Caracas the incidence of SE constitutes a potentially significant epidemic situation, when we take into account that in Caracas we find a highly concentrated human population together with a highly dangerous scorpion, Tityus discrepans, Pocock, 1897.
Brown widow spider (BrWS) (
Latrodectus geometricus) venom produces intense systemic reactions such as cramps, harsh muscle nociceptive, nauseas, vomiting and hypertension. The proposed pathogenic ...mechanisms resulting in these accidents have principally been damages occurring at the nervous system. However, it is suspected that there is also damage of the adrenal glands, as a result of the experimental animal's clinical manifestations, which developed symptoms compatible with acute adrenal insufficiency. We have currently found that the adrenal gland is damaged by this venom gland homogenates (VGH) producing severe alterations on cortex cells resulting in death by acute adrenal insufficiency. In general, the ultrastructural study on the glands of mice under transmission electronic microscopy observations showed alterations in the majority of the intracellular membranes within 3 to 24
h. BrWSVGH also showed specific actions on extracellular matrix proteins such as fibronectin, laminin and fibrinogen. In addition, zymogram experiments using gelatin as substrates detected gelatinolytic activity. The molecular exclusion fractionation of crude BrWSVGH resulted in 15 fractions, of which F1 and F2 presented α/β-fibrinogenase and fibronectinolytic activities. Fractions F6, F14 and F15 showed only α-fibrinogenase activity; in contrast, the gelatinolytic action was only observed in fraction F11. Only metalloproteinase inhibitors abolished all these proteolytic activities. Our results suggest that adrenal cortex lesions may be relevant in the etiopathogenesis of severe brown widow spider envenoming. To our knowledge, this is the first report on adrenal gland damages, fibrinogenolytic activity and interrelations with cell-matrix adhesion proteins caused by
L.
geometricus VGH. The venom of this spider could be inducing hemostatic system damages on envenomed patients.
Todos los animales colectados provienen del pueblo de Capaya, Distrito Brión, estado Miranda, Venezuela, población asentada en el piedemonte de la vertiente que mira al sur de la Cordillera de la ...Costa, en una región donde se confunden dos pisos altitudinales, una zona semiselvática, donde predomina la vegetación exuberante de selva macrotérmica, por debajo de los 800 metros sobre el nivel del mar, que se hace mesotérmica nublada por encima de esta altura. La búsqueda de los ejemplares se hizo, explorando los matorrales y escombros, alrededor de las viviendas de ubicación periselvática y utilizando pinzas largas de puntas acolchadas para su captura. Este trabajo, recoge las observaciones biológicas y el estudio histopatológico (microscopía de luz), de tejidos de ratón inoculados con el veneno de Scolopendra gigantea Linnaeus 1758. En tejido muscular estriado fueron observadas fibras con cambios estructurales y se apreciaron fenómenos de rabdiomiolisis. La mayoría de fibras del músculo en todos los campos observados presentaron anormalidades severas como atrofia, zonas de necrosis segmentaria, hipercontracción e infiltrados inflamatorios, en algunas de ellas, la hipercontracción dio origen a plegamientos del sarcolemma. El hígado agrandado ligeramente y de color suave y rojizo, sin áreas de hemorragia; su histopatología mostró hepatocitos con degeneración hidrópica y vacuolación fina en áreas de su citoplasma. Se pudo observar también zonas de necrosis muy focalizada.
Rodríguez-Acosta A, Reyes-Lugo M. 2004. Hallazgo de Tityus bahiensis (Perty 1833) (Scorpiones: Buthidae) en Venezuela. Entomotropica 19(2):107-108.
Tityus bahiensis (Perty 1833) es una especie de ...escorpión de alta peligrosidad de amplia distribución en Brasil (desde el estado de Bahía hasta el Mato Grosso) norte de la Argentina y Paraguay. En el casco urbano de Caracas es frecuente encontrar escorpiones en las casas, pero el hallazgo de un ejemplar hembra de T. bahiensis muerto, tiene la significación teórica de representar una vía potencial de introducción de un animal ponzoñoso de forma accidental y denota la importancia de las medidas de control en puertos y aeropuertos a fin de reducir la introducción de fauna exótica con posibilidad de establecimiento.
Introduction. In the last years, the incursions
and domiciliary populations of Panstrongylus
geniculatus Latreille 1811 have increased in
Venezuela.
Objective. To analyze the P. geniculatus ...introduction
in homes of the center-north of Venezuela, relating it with peri and intra-domiciliary macro and micro
ambient, characterize interaction with human and
domestic animals and the Trypanosoma cruzi natural
infection index (TcNII) is evaluated.
Materials and Methods. Captures of P. geniculatus
in the center-north of Venezuela (Caracas and
Aragua, Miranda and Vargas states) are related
with the macro-environment (altitude, humidity,
temperature and precipitation); the home (housing
type-color, type-color of external illumination
and it distances to the forest); inhabitants’ density
and housings; percentage of vegetation; housings
distribution in the space of and public illumination.
The interrelations are analyzed with ANOVA,
Multiple regression and Lineal Regression Forward
Step Wise, and satellite images. The triatominebites
to humans are correlated with abundances of
potential sources of blood ingestion (human and/or
animal). The TcNII was determined in triatomine
feces.
Results. In the center-north of Venezuela the
presence of P. geniculatus during the evening, in
the area to be domiciled related with: vegetation
<21%, temperature 24-26ºC, HR50-80%, number
of animal/housing >5 and number people more
animals/housing ≥13. From 1906 interviewed
people, 159 had contacted with P. geniculatus being
86 triatomine-bitten. The TcNII was between 20
and 100%.
Conclusions. The presence of P. geniculatus
adults during the evening was independent of the
housing type, increasing with the decrease of: % of
vegetation, domestic animals, distances from the
forest and when the lights were on
Introducción. En Venezuela, en los últimos años,
se han incrementado las incursiones y poblaciones
domiciliarias de Panstrongylus geniculatus
Latreille 1811.
Objetivo. Analizar la introducción de P. geniculatus
en domicilios del centro-norte de Venezuela,
relacionarla con el macro y microambiente peri
e intradomiciliario, caracterizar la interacción
con humanos y animales domésticos, y evaluar
el índice de infección natural con Trypanosoma
cruzi (IINTc).
Materiales y Métodos. En el centro-norte de
Venezuela (Gran Caracas y los estados Aragua,
Miranda y Vargas), las capturas de P. geniculatus
con participación comunitaria se relacionan con: el
macroambiente (altitud, humedad, temperatura y
precipitación), el domicilio (tipo-color de vivienda,
tipo-color de iluminación externa y distancia
al bosque), densidad de habitantes y viviendas,
porcentaje de cobertura de vegetación (% CV),
distribución espacial de viviendas y alumbrado
público. Las interrelaciones se analizan con
ANOVA, Regresión Múltiple y Regresión Lineal
Forward StepWise, e imágenes satelitales con el
programa Adobe Photoshop CS. Se correlacionan
los contactos-picadas a humanos con la abundancia
de potenciales fuentes de ingesta sanguínea
(humana y/o animal). El IINTc se determinó al
microscopio en heces del triatómino.
Resultados. En el centro-norte de Venezuela,
la presencia nocturna de P. geniculatus en el
área domiciliaria se relaciona con: cobertura de
vegetación<21%, temperatura 24-26ºC, HR 50-
80%, número de animales/vivienda>5 y número
de personas más animales/vivienda>=13. De 1906
personas encuestadas, 159 tuvieron contacto con
P. geniculatus, resultando picadas 86. El IINTc
encontrado estuvo entre 20% y 100%.
Conclusiones. La presencia nocturna de adultos
de P. geniculatus es independiente del tipo de
vivienda, incrementando con la disminución de:
% CV, animales domésticos, distancia al bosque
y luces encendidas.
This review describes the changes produced by the invasión of the
urban environment into the natural habitat of triatomines, especially
Panstrongylus geniculatus , known vectors of Chagas' disease.
...Changes in habitat are described and the colonization of domestic
environments by triatomines, as well as the importance of these changes
and their impact on transmission of Chagas' disease. Some
measures are proposed to limit the presence of triatomines in urban
dwellings
Historically known as the yellow fever mosquito, Aedes aegypti invaded Madeira Island in 2005 and was the vector of the island's first dengue outbreak in 2012. We have studied genetic variation at 16 ...microsatellites and two mitochondrial DNA genes in temporal samples of Madeira Island, in order to assess the origin of the invasion and the population structure of this mosquito vector. Our results indicated at least two independent colonization events occurred on the island, both having a South American source population. In both scenarios, Venezuela was the most probable origin of these introductions, a result that is in accordance with the socioeconomic relations between this country and Madeira Island. Once introduced, Ae. aegypti has rapidly expanded along the southern coast of the island and reached a maximum effective population size (N
) in 2012, coincident with the dengue epidemic. After the outbreak, there was a 10-fold reduction in N
estimates, possibly reflecting the impact of community-based vector control measures implemented during the outbreak. These findings have implications for mosquito surveillance not only for Madeira Island, but also for other European regions where Aedes mosquitoes are expanding.
PDF
