Teaching evolution to psychiatrists in Venezuela: comparison with medical students and other medical specialists: a pilot study

Introduction: The teaching of evolution theory (ET) in medical programs has received scant attention in the literature. In this report, we first describe the main applications of ET in medicine. Second, we present the evaluation of an interactive seminar on ET given to groups of medical students, psychiatrists, and other medical specialists. Methods: A two-hour, four-module, interactive seminar was conducted with separate groups of 27 psychiatrists, 15 family doctors, 18 neurologists, 13 physiatrists, 12 internists, and 24 sixth-year medical students without formal training in ET. Their knowledge of ET before and after the seminar was rated on a validated analogical scale (0-12). In addition, the perceived relevance of the information for the participants’ professional activity was assessed. Results: Score averages and medians before the seminar were below 6, suggesting low to moderate knowledge. The students' scores did not differ significantly from those of the physicians except on the Hominization item, where they scored lower than the physicians (p = 0.02). The psychiatrists’ scores did not differ from those of the other groups before the seminar, but after the seminar the increase in their scores on a number of items was significantly smaller than that of the other groups. While all groups scored 10 or more when assessing the relevance of the information, the psychiatrists had the lowest score (p = 0.024). Discussion: The results show the adequacy of short programs to enhance knowledge on ET. This may assist medical educators to develop comprehensive and compulsory courses. Future studies must explore whether psychiatrists are relatively reluctant or ambivalent to accept evolution concepts and proposals.

Study of hemolymphatic components of Rhodnius prolixus and Triatoma maculata fed on different blood sources

 Introduction: Traditionally Rhodnius prolixus has been considered the main vector and Triatoma maculata as a secondary vector of Trypanosoma cruzi in the Venezuelan rural habitat. In this work, we show interesting information about the biochemical components and the immune system, humoral and cellular, of the hemolymph of R. prolixus and T. maculata feeding on hen and rat. Methodology: Hemolymph was extracted from adults insects, maintained at 27-29 °C, 50% relative humidity and 8/16 (Light/Dark) hours, and fed on hen and rat. Hemocytes were observed by optical microscopy and transmission electron microscopy. Results: Biochemical parameters such as glucose, lipids and proteins varied in both species according to the food source. T. maculata presented higher levels of lysozyme lytic activity. Four hemocytes populations were observed by optical and transmission electron microscopy, prohemocytes, plasmocytes, granulocytes and oenocytes, their characteristics and measures are in accordance with previous reports by other authors in the subfamily Triatominae. T. maculata presented more prohemocytes and oenocytes than R. prolixus. Conclusions: R. prolixus and T. maculata are distinctly affected in their biochemical hemolymphatic components (glucose, lipids and proteins) as well as humoral (lysozyme) and cellular (prohemocytes, oenocytes) inmune components, depending on whether they were fed on hens or rats. Our results show that the food source affects the immune system of triatomines, thus their vectorial capacity might affected as well.  Introducción: Tradicionalmente Rhodnius prolixus ha sido considerado el principal vector y Triatoma maculata como un vector secundario de Trypanosoma cruzi en el medio rural venezolano. En este trabajo nos planteamos aportar información de interés acerca de los componentes bioquímicos y del sistema inmune, humoral y celular, de la hemolinfa de R. prolixus y T. maculata alimentando sobre gallina y rata. Metodología: los insectos provenían de una colonia del laboratorio mantenida a una temperatura de 27-29ºC, 50% humedad relativa y ocho horas luz/16 horas oscuridad. Se analizó la hemolinfa de adultos alimentados sobre gallina y rata. Se observaron los hemocitos mediante microscopía óptica y electrónica de transmisión. Resultados: los parámetros bioquímicos glucosa, lípidos y proteínas fueron afectados de forma distinta en R. prolixus y T. maculata según la fuente alimenticia. T. maculata presentó mayores niveles de actividad lítica de lisozima. Se observaron cuatro poblaciones de hemocitos: prohemocitos, plasmatocitos, granulocitos y oenocitos, cuyas características y medidas están acorde a lo reportado por otros autores en la subfamilia Triatominae. T. maculata presentó mayor número de prohemocitos y oenocitos que R. prolixus. Conclusiones: R. prolixus y T. maculata son afectados distintamente en sus componentes hemolinfáticos bioquímicos (glucosa, lípidos y proteínas) y del sistema inmune humoral (lizosima) y celular (prohemocitos, oenocitos), según sean alimentados sobre gallina y rata, lo que pone de manifiesto cómo afecta la alimentación a uno de los componentes de la competencia vectorial como lo es el sistema inmune que reside en la hemolinfa de estos insectos.&nbsp

Orientation of Belminus triatomines to cockroaches and cockroaches’ fecal volatiles: an ethological approach

Most triatomine bugs (Hemiptera: Reduviidae: Triatominae) are hematophagous, though Belminus species can live off of cockroach hemolymph to complete their life cycle. In this work we described the fixed action pattern (FAP) employed by B. ferroae to identify, approach and suck on a living cockroach. The FAP described here is composed of the following stereotyped behaviors: 1) visual and/or olfactory detection of the cockroach, 2) reaching, 3) cautious approach, 4) antennal exploration, 5) extension of the proboscis, 3) piercing to sedate, 5) walking  away and waiting (post sedation behavior), 6) second cautious approach, 7) extension of the proboscis, 8) piercing to suck hemolymph. In order to identify chemicals cues that could elicit such FAP, we examined the behavior of B. corredori, B. ferroae and B. herreri in response to the cockroaches’ odor, fresh cockroach feces and fresh rodent wastes. The last two sources were tested based on the assumption that abundant chemicals near host refuges could serve as cues for host orientation. We found the cockroach odor emanating from a box significantly attracted B. herreri in a still air olfactometer. The three Belminus species approached the captive cockroach after one hour, but avoided to climb the box. Odors emanating from the cockroach feces attracted B. corredori and B. ferroae in a Y-olfactometer. The FAP sequence observed suggests Belminus bugs are not predators like the rest of reduviids (assassin bugs) —but are kleptophagous ectoparasites, since they do not attack and kill a prey but rather steal hemolymph from its invertebrate host. Triatomines and their hosts have intimately shared the same refuge for millions of years. Similar odors occur across invertebrate and vertebrate refuges, and are recurrent in human abodes, thus plausibly explaining how these kleptophagous bugs can readily switch to the domestic habitat

Perfil de la mortalidad de hembras de Rhodnius robustus (Heteroptera: Reduviidae)

Mortality profile of 48 adult females of Rhodnius robustus shows that data analyzed by weeks and days have a statistical significantly fit (pSe estudió la mortalidad de 48 hembras adultas de Rhodnius robustus. Dada la significancia estadística del ajuste de los datos al modelo de Gompertz (

Exposure to citral, cinnamon and ruda disrupts the life cycle of a vector of Chagas disease

The main vector of Chagas disease in Venezuela was exposed to the odors of citral, cinnamon and ruda. Cinnamon was found to stop the life cycle of Rhodnius prolixus relative to untreated animals. Citral and ruda also influenced the life cycle but not to the extent of animals exposed to cinnamon. We suggest that future research be directed toward using cinnamon in field and toxicity tests.Peer reviewedPsychologyZoolog

Descripción de setas cuticulares externas de cabeza, tórax, patas, abdomen y genitales en cuatro especies de Triatominae

Introduction: The classification of the cuticular extensions of insects has been proposed as a taxonomic tool; however, the internal and external processes of the cuticular extensions of the Triatominae subfamily have not been fully analyzed and categorized. Objective: To describe the setae from different regions of the outer cuticle of several triatomine species by scanning electron microscopy. Materials and methods: Triatomines were washed and dried, after which different regions of the body from Eratyrus mucronatus, Triatoma maculata, Panstrongylus geniculatus and Belminus ferroae specimens were dissected, mounted on graphite double-sided adhesive tape over metal supports, metalized with gold and micrographed for further analysis. Results: We described nine types of cuticular setae. We found five types of setae in B. ferroae and T. maculata, four in P. geniculatus and only one in E. mucronatus. According to the proposed typology, type 3 seta was the most common in T. maculata, P. geniculatus and E. mucronatus, whereas type 1a predominated in B. ferroae. Conclusion: Type 3 seta was the most common in the Triatomini tribe (T. maculata, E mucronatus and P. geniculatus), whereas type 1a seta was specific to B. ferroae (tribe Bolboderini), suggesting that the surface morphology of the setae may have taxonomic value at tribe taxonomic level.Introducción. Se han propuesto clasificaciones de las extensiones cuticulares de los insectos para utilizarlas como herramienta taxonómica. A pesar de los diversos estudios morfológicos adelantados en triatominos, el conocimiento que se tiene sobre la distribución y los tipos morfológicos de estas estructuras en la subfamilia aún es escaso y fragmentario. Objetivo. Describir las setas de diferentes regiones de la cutícula externa de varias especies de triatominos mediante microscopía electrónica de barrido. Materiales y métodos. Se lavaron y se secaron especímenes de Eratyrus mucronatus, Triatoma maculata, Panstrongylus geniculatus y Belminus ferroae, y a continuación se disecaron diferentes regiones de sus cuerpos y se montaron sobre cinta adhesiva de grafito de doble faz en soportes metálicos. Se metalizaron con oro y se tomaron las micrografías para su posterior análisis. Resultados. Se describieron nueve tipos de setas cuticulares. En B. ferroae y T. maculata se encontraron cinco tipos de setas, en P. geniculatus, cuatro, y en E. mucronatus, un solo tipo. Según la tipología propuesta, la seta de tipo 3 fue la más común en cada especie, excepto en B. ferroae, en la cual predominó la seta de tipo 1a. Conclusión. La seta más común en las especies de la tribu Triatomini (T. maculata, E. mucronatus y P. geniculatus) fue la de tipo 3; la seta de tipo 1a fue específica para la especie B. ferroae, taxón de la tribu Bolboderini, lo cual permite suponer que la morfología superficial de las setas podría tener valor taxonómico a nivel de tribu

Evolution of Hematophagous Habit in Triatominae (Heteroptera: Reduviidae)

All members of Triatominae subfamily (Heteroptera: Reduviidae), potential vectors of Trypanosoma cruzi, etiologic agent of the Chagas disease, feed on blood. Through evolution, these bugs have fixed special morphological, physiological, and behavioral aptations (adaptations and exaptations) adequate to feed on blood. Phylogeny suggests that triatomines evolved from predator reduvids which in turn descended from phytophagous hemipterans. Some pleisiomorphic traits developed by the reduvid ancestors of the triatomines facilitated and modeled hematophagy in these insects. Among them, mouthparts, saliva composition, enzymes, and digestive symbionts are the most noticeable. However, the decisive step that allowed the shift from predation to hematophagy was a change of behavior. The association of a predator reduvid with nesting vertebrate (≈110 to 32 Ma) permitted the shift from an arthropod prey to a vertebrate host. In this work, we review the phylogeny and dispersion of triatomines and the current controversy over the monophyly or polyphyly of this group. We also discuss how these insects were able to overcome, and even have taken advantage of, diverse ancestral and physical barriers to adapt to sucking blood of nidicolous vertebrates

Estudio entomológico de vectores transmisores de la infección por Trypanosoma cruzi en la población rural del estado Sucre, Venezuela

Introduction: The ecological niche of Reduvidae vectors has been modified due to environmental changes and human encroachment into the rural areas.Objective: This study evaluates the current entomological indices of triatomines responsible for Trypanosoma cruzi infection in Sucre State, Venezuela.Materials and methods: A cross-sectional and prospective study was conducted in 95 towns and 577 dwellings in the 15 municipalities of the state of Sucre, Venezuela, from August to November, 2008. Triatomine bugs were identified on the basis of morphological characteristics, and their feces examined for T. cruzi infection through direct microscopy. Positive slides were stained with Giemsa and parasites were identified by morphologic characterization.Results: The entomological indices expressing the highest values were dispersion (16.67%) and household colonization (33.33%). The triatomine species captured were: Rhodnius prolixus, Rhodnius pictipes, Rhodnius robustus, Panstrongylus geniculatus, and Triatoma maculata, the latter being the main intradomiciliaryvector.Conclusions: Despite the low index of vector infection (1.72%), the existence of species with domiciliary and peridomiciliary reproductive success ensures the persistence of the epidemiological chain both for the disease and the parasite.Introducción. Debido a los cambios ambientales y a la intervención del hombre en los espacios silvestres, se ha cambiado el nicho ecológico de los vectores reduvídeos.Objetivo. En el presente estudio se evaluó la situación actual de los índices entomológicos de los triatominos responsables de la transmisión de Trypanosoma cruzi en el estado Sucre.Materiales y métodos. Se llevó a cabo un estudio prospectivo transversal en 96 centros poblados y 576 viviendas de los 15 municipios del estado Sucre, Venezuela, entre agosto y noviembre de 2008. Los vectores se identificaron con base en sus características morfológicas. La identificación de Trypanosoma spp. en las heces de los triatominos se hizo mediante el examen directo por microscopía. Las láminas positivas se tiñeron con Giemsa y los parásitos se identificaron por sus características morfológicas.Resultados. Los índices entomológicos con los valores más elevados fueron la dispersión en centros poblados rurales del estado Sucre (16,67 %) y la colonización de las viviendas (33,33 %). Las especies de triatominos capturados fueron Rhodnius prolixus, Rhodnius pictipes, Rhodnius robustus, Triatoma maculata y Panstrongylus geniculatus, siendo T. maculata el principal vector en el domicilio.Conclusiones. A pesar del bajo índice de infección natural en vectores (1,72 %), la existencia de especies con éxito reproductivo en el domicilio y el peridomicilio puede garantizar el mantenimiento de la cadena epidemiológica, tanto de la enfermedad como del parásito

Evaluación de la estructura espacial de Triatoma maculata del centro-occidente de Venezuela y su viabilidad alimentado con sangre humana en condiciones de laboratorio

Introduction. Immature and adult forms of Triatoma maculata have been captured repeatedly in and around the homes in the town of Xaguas, Venezuela. Because of its potential as a Chagas disease vector, a study was undertaken to evaluate the effect of human blood feeding on the viability and spatial structuring of a laboratory colony of this species .Objective. The effect of human blood feeding was determined for the viability of a T. maculata laboratory colony, as well as its spatial structuring.Material and methods. Insects were fed with human blood on artificial feeder. Spatial structuring was undertaken by the generalized analysis of by geometric morphometry.Results. The average fecundity of 27.7 eggs/female/lifetime was found, with a mean time to oviposition of 32.7 days, and a female longevity of 39.2 days. The longest inter-molt period was at the fifth nymphal stage (45.9 days), whereas the shortest was at 18.4 days, during the first nymphal stage. The highest mortality of nymphs was observed at the fifth nymphal stage (77.8%). The lowest molting percentage was observed in the fifth nymphal stage (22.2%). No differences in the size of wings and heads were detectable; although differences in the head shape of individuals of the same sex from different environments were noted. Wing-shape differences were found only between the males of peridomestic and domestic ecotopes.Conclusions. Triatoma maculata may be entering human dwellings to feed on non-human animals, or alternatively, may be in an incipient state of adaptation to a domestic ecotope for feeding on human beings.Introducción. Dado el reiterado hallazgo de adultos y formas inmaduras de Triatoma maculata capturados en domicilios y peridomicilios en la localidad de Xaguas (Venezuela), se analizó la viabilidad de una colonia de laboratorio de esta especie alimentada con sangre humana y su estructura espacial.Objetivos. Analizar la viabilidad del ciclo de T. maculata alimentado con sangre humana en condiciones de laboratorio y caracterizar la estructura espacial de una población de T. maculata proveniente de ambientes domiciliarios y peridomiciliarios del centro-occidente de Venezuela.Materiales y métodos. La alimentación con sangre humana se llevó a cabo en lotes por estadio, utilizando un alimentador artificial, y la estructura espacial de los insectos por sexo y ambiente fue analizada mediante morfometría geométrica.Resultados. Los hallazgos fueron: fecundidad promedio, 27,70 huevos/hembra/vida, tiempo promedio de postura de huevos, 32,74 días, y longevidad promedio de la hembra, 39,15 días; el mayor tiempo en V estadio fue de 45,9 días y el menor en I estadio, 18,41 días; la mayor mortalidad fue de 77,78% y el menor porcentaje de muda en V estadio, de 22,23%.No se encontraron diferencias en el tamaño de alas y cabezas; sí se encontraron diferencias de conformación entre las cabezas de un mismo sexo de diferentes hábitats; sólo se encontraron diferencias de conformación de alas entre los machos del domicilio y peridomicilio.Conclusiones. T. maculata de la localidad de Xaguas podría encontrarse en un estado de adaptación al domicilio con fuentes sanguíneas diferentes al humano y en un estado incipiente de adaptación al domicilio con la sangre humana como fuente de alimentación