The presence of metacyclical promastigotes of Leishmania pifanoi in the hypopharyngeal duct of Lutzomyia youngi is reported. The insects were experimentally infected by engorgement on the tarsal lesions of hamsters. The metacyclics, whose morphology is illustrated, appeared in the hypopharynx 5 to 9 days after engorgement; they were more frequently found in the insects fed on unrefined commercial sugar. They role of amino derivates of glucose and galactose, as well as of amino acids in the development and migration of metacyclics, is investigated.

Se evidencia la presencia de promastigotos metacíclicos de Leishmania pifanoi en el conducto hipofaríngeo de Lutzomyia youngi infectados experimentalmente por ingurgitación sobre lesiones tarsales de hámsteres. La aparición de metacíclicos en la hipofaringe, cuya morfología se ilustra, ocurre entre los 5 y 9 días de desarrollo postprandial y es más frecuente en insectos alimentados con sacarosa comercial no refinada. Se investiga el papel de derivados aminados de glucosa y galactosa y también de aminoácidos, en la promoción y migración de los metacíclicos.

The presence of metacyclical promastigotes of Leishmania pifanoi in the hypopharyngeal duct of Lutzomyia youngi is reported. The insects were experimentally infected by engorgement on the tarsal lesions of hamsters. The metacyclics, whose morphology is illustrated, appeared in the hypopharynx 5 to 9 days after engorgement; they were more frequently found in the insects fed on unrefined commercial sugar. They role of amino derivates of glucose and galactose, as well as of amino acids in the development and migration of metacyclics, is investigated.

Se evidencia la presencia de promastigotos metacíclicos de Leishmania pifanoi en el conducto hipofaríngeo de Lutzomyia youngi infectados experimentalmente por ingurgitación sobre lesiones tarsales de hámsteres. La aparición de metacíclicos en la hipofaringe, cuya morfología se ilustra, ocurre entre los 5 y 9 días de desarrollo postprandial y es más frecuente en insectos alimentados con sacarosa comercial no refinada. Se investiga el papel de derivados aminados de glucosa y galactosa y también de aminoácidos, en la promoción y migración de los metacíclicos.

The increase in the promastigotes population of Leishmania pifanoi in Lutzomyia youngi experimentally infected and kept on 50% sacarose under constant conditions of temperature and humidity is described. Two stages in the differentation and growth of the parasites are recognised between two and twenty-four hours after meals. The pleomorphic differentiation of the amastigotes in short promastigotes which multiply by binary division for 60 hours, when the rupture of the peritrophic membrane occurs, takes place within 48 hours. The second stage occurs between 72 and 96 hours when some of the parasites migrate to the esophagic valve and the rest of the free parasites are excreted in fecal drops as large, active promastigotes. The first drops excreted react positively to glucose or contain crystals of urate. The excess promastigotes of the second stage of development are eliminated in the last excretions and react positively to the Hemoscreen and Biuret tests for total proteins as also for glucose and account for 82% of the of drops excreted. The excretion of parasites by Lu. youngi is a normal stage in the growth of L. pifanoi into a vector.

Se describe el desarrollo poblacional promastigótico de Leishmania pifanoi en Lutzomyia youngi experimentalmente infectada y mantenida con sacarosa al 50% bajo condiciones constantes de temperatura y humedad. Se reconocen dos etapas para la diferenciación y el crecimiento de los parásitos entre las dos y ciento veinte horas postprandiales. Hasta 48 horas tiene lugar la diferenciación pleomórfica de amastigotos en promastigotos cortos, que se multiplican por división binaria hasta las 60 horas, cuando ocurre la ruptura de la membrana peritrófica. La segunda etapa tiene lugar entre las 72 y 96 horas cuando algunos parásitos migran hacia la válvula esofágica y los demás parásitos libres son excretados en gotitas fecales como promastigotos grandes y activos. Las primeras gotitas excretadas dan reacción positiva a glucosa o contienen cristales de urato. El exceso de promastigotos de la segunda fase de desarrollo es eliminado en las últimas excretas que dan reacción positiva con las pruebas Hemoscreen y Biuret para proteínas totales y también para glucosa, y constituyen el 82% del total de gotas excretadas. La excreción de parásitos por Lu. youngi es fase normal del desarrollo de L. pifanoi en un vector.

The increase in the promastigotes population of Leishmania pifanoi in Lutzomyia youngi experimentally infected and kept on 50% sacarose under constant conditions of temperature and humidity is described. Two stages in the differentation and growth of the parasites are recognised between two and twenty-four hours after meals. The pleomorphic differentiation of the amastigotes in short promastigotes which multiply by binary division for 60 hours, when the rupture of the peritrophic membrane occurs, takes place within 48 hours. The second stage occurs between 72 and 96 hours when some of the parasites migrate to the esophagic valve and the rest of the free parasites are excreted in fecal drops as large, active promastigotes. The first drops excreted react positively to glucose or contain crystals of urate. The excess promastigotes of the second stage of development are eliminated in the last excretions and react positively to the Hemoscreen and Biuret tests for total proteins as also for glucose and account for 82% of the of drops excreted. The excretion of parasites by Lu. youngi is a normal stage in the growth of L. pifanoi into a vector.

Se describe el desarrollo poblacional promastigótico de Leishmania pifanoi en Lutzomyia youngi experimentalmente infectada y mantenida con sacarosa al 50% bajo condiciones constantes de temperatura y humedad. Se reconocen dos etapas para la diferenciación y el crecimiento de los parásitos entre las dos y ciento veinte horas postprandiales. Hasta 48 horas tiene lugar la diferenciación pleomórfica de amastigotos en promastigotos cortos, que se multiplican por división binaria hasta las 60 horas, cuando ocurre la ruptura de la membrana peritrófica. La segunda etapa tiene lugar entre las 72 y 96 horas cuando algunos parásitos migran hacia la válvula esofágica y los demás parásitos libres son excretados en gotitas fecales como promastigotos grandes y activos. Las primeras gotitas excretadas dan reacción positiva a glucosa o contienen cristales de urato. El exceso de promastigotos de la segunda fase de desarrollo es eliminado en las últimas excretas que dan reacción positiva con las pruebas Hemoscreen y Biuret para proteínas totales y también para glucosa, y constituyen el 82% del total de gotas excretadas. La excreción de parásitos por Lu. youngi es fase normal del desarrollo de L. pifanoi en un vector.

Homogenized biopsy tissue from the cutaneous leishmaniasis lesions of 50 patients from Trujillo, Venezuela, were inoculated subcutaneously into the tarsi of male hamsters. Homogenized tissue either alone or mixed with salivary gland lysates of Lutzomyia youngi were used for inoculation. Homogenized tissue alone yielded 58.5% of infections with a mean of twelve weeks for prepatency, while those mixed with sandfly lysate resulted in 92% of infections with a mean prepatency of three weeks.

Homogeneizados de biopsias de lesiones cutáneas de 50 casos de leishmaniasis tegumentaria de Trujillo, Venezuela, han sido inoculados en hámsteres machos. Se ha comparado la infectvidad de Leishamania braziliensis, de homogeneizados simples, con la de los mezclados con lisado de glándula salival de Lutzomyia youngi, registrandose un 58,5% de infecciones para una media de 12 semanas de prepatencia con los homogeneizados simples, contra 92% de infecciones con una media de 3 semanas de prepatencia, cuando cada uno de los inóculos de homogeneizado se mezcló con lisado equivalente al de una glándula salival de flebótomo.

Homogenized biopsy tissue from the cutaneous leishmaniasis lesions of 50 patients from Trujillo, Venezuela, were inoculated subcutaneously into the tarsi of male hamsters. Homogenized tissue either alone or mixed with salivary gland lysates of Lutzomyia youngi were used for inoculation. Homogenized tissue alone yielded 58.5% of infections with a mean of twelve weeks for prepatency, while those mixed with sandfly lysate resulted in 92% of infections with a mean prepatency of three weeks.

Homogeneizados de biopsias de lesiones cutáneas de 50 casos de leishmaniasis tegumentaria de Trujillo, Venezuela, han sido inoculados en hámsteres machos. Se ha comparado la infectvidad de Leishamania braziliensis, de homogeneizados simples, con la de los mezclados con lisado de glándula salival de Lutzomyia youngi, registrandose un 58,5% de infecciones para una media de 12 semanas de prepatencia con los homogeneizados simples, contra 92% de infecciones con una media de 3 semanas de prepatencia, cuando cada uno de los inóculos de homogeneizado se mezcló con lisado equivalente al de una glándula salival de flebótomo.

Batches of sylvatic females of Lutzomyia youngi (Phlebotominae) captured in a Shannon trap on twelve occasions over one year in a locality where subcutaneous leishmaniasis is endemic, near the city of Trujillo, Venezuela, were used to study: 1) the percentages of parous females according to previously established criteria and 2) the average number of eggs laid spontaneously by isolated females during 7 days after feeding on hamsters. The data on the batches of females captured on nights previous to the rainy period (prepluvial) were compared with those on females captured after the rains (postpluvial) . Significant differences were detected by variation analysis for two variables and different number of N, as also were consistent groupings by Duncan's Test for pre-and postpluvial lots of females. The females captured on nights prior to the rainy periods (January-March and August-September) presented higher rates of nulliparity (86-72%) and contained or laid a greater number of eggs (71-67) than those captured after the rains (March-June and November-December) which presented lower rates of nulliparity (60-24%) and a smaller number of eggs (50-30). The rainfall peaks occurred in April and September-October, respectively. It is considered that these differences can be used by epidemiological studies as a means of estimating the physiological age of female populations of L. youngy.

Con lotes de hembras silvestres de Lutzomyia youngi (Phlebotominae) capturadas con trampa de Shannon en doce ocasiones a lo largo de un año, en una localidad endémica para leishmaniasis tegumentaria, próxima a la ciudad de Trujillo, Venezuela, se estudio: 1) los percentajes de hembras paridas según criterios previamente establecidos y 2) el número medio de huevos puestos espontaneamente por hembras aisladas, en el curso de 7 días postigestión, ingurgitadas también sobre hámsteres. Se comparó la data de lotes de hembras capturadas, en noches de días anteriores a los períodos de lluvias (prepluviales) con las de hembras capturadas después de las lluvias (postpluviales). Se detectó diferencias significativas por análisis de varianza para dos variables y diferente número de N, y también consistentes agrupaciones con la prueba de Duncan para lotes de hembras pre y postpluviales. Las hembras capturadas en noches previas a los periodos de lluvias (Enero - Marzo y Agosto - Septiembre) exhibieron más altas tasas de nuliparidad (86-72%) y contuvieron o eliminaron mayor número de huevos (71-67), que las hembras capturadas después de las lluvias (Marzo-Junio y Noviembre - Diciembre), con mas bajas tasas de nuliparidad (60-24%) y menores números de huevos (50-30). Los picos de lluvias ocurrieron en Abril y Septiembre - Octubre, respectivamente. Se considera que estas diferencias puedan ser utilizadas, como una estimativa de la edad fisiológica de problaciones de hembras de L. youngi, en estudios epidemiológicos.

Batches of sylvatic females of Lutzomyia youngi (Phlebotominae) captured in a Shannon trap on twelve occasions over one year in a locality where subcutaneous leishmaniasis is endemic, near the city of Trujillo, Venezuela, were used to study: 1) the percentages of parous females according to previously established criteria and 2) the average number of eggs laid spontaneously by isolated females during 7 days after feeding on hamsters. The data on the batches of females captured on nights previous to the rainy period (prepluvial) were compared with those on females captured after the rains (postpluvial) . Significant differences were detected by variation analysis for two variables and different number of N, as also were consistent groupings by Duncan's Test for pre-and postpluvial lots of females. The females captured on nights prior to the rainy periods (January-March and August-September) presented higher rates of nulliparity (86-72%) and contained or laid a greater number of eggs (71-67) than those captured after the rains (March-June and November-December) which presented lower rates of nulliparity (60-24%) and a smaller number of eggs (50-30). The rainfall peaks occurred in April and September-October, respectively. It is considered that these differences can be used by epidemiological studies as a means of estimating the physiological age of female populations of L. youngy.

Con lotes de hembras silvestres de Lutzomyia youngi (Phlebotominae) capturadas con trampa de Shannon en doce ocasiones a lo largo de un año, en una localidad endémica para leishmaniasis tegumentaria, próxima a la ciudad de Trujillo, Venezuela, se estudio: 1) los percentajes de hembras paridas según criterios previamente establecidos y 2) el número medio de huevos puestos espontaneamente por hembras aisladas, en el curso de 7 días postigestión, ingurgitadas también sobre hámsteres. Se comparó la data de lotes de hembras capturadas, en noches de días anteriores a los períodos de lluvias (prepluviales) con las de hembras capturadas después de las lluvias (postpluviales). Se detectó diferencias significativas por análisis de varianza para dos variables y diferente número de N, y también consistentes agrupaciones con la prueba de Duncan para lotes de hembras pre y postpluviales. Las hembras capturadas en noches previas a los periodos de lluvias (Enero - Marzo y Agosto - Septiembre) exhibieron más altas tasas de nuliparidad (86-72%) y contuvieron o eliminaron mayor número de huevos (71-67), que las hembras capturadas después de las lluvias (Marzo-Junio y Noviembre - Diciembre), con mas bajas tasas de nuliparidad (60-24%) y menores números de huevos (50-30). Los picos de lluvias ocurrieron en Abril y Septiembre - Octubre, respectivamente. Se considera que estas diferencias puedan ser utilizadas, como una estimativa de la edad fisiológica de problaciones de hembras de L. youngi, en estudios epidemiológicos.

Tem-se estudado a diversidade e a riqueza de larvas de Anopheles (Nyssorhynchus) spp. em 22 postos permanentes e temporais em área de 70 km² ao pé da Cordilheira Andina Oriental da Venezuela, em região de malária refratária. Foram identificadas 12 espécies, sendo as mais freqüentes, abundantes e simpátricas as A. triannulatus, A. albitarsis, A. nuñeztovari, A. oswaldoi y A. strodei. Foi maior o número de espécies e de larvas por amostra nos postos permanentes do que nos temporais. A existência das mesmas associações larvais, em postos de outras localidades, ao pé da Cordilheira Andina Oriental da Venezuela, baseia-se no ponto de vista de que é possível fazer-se um mapa ecológico dos criadouros dessas espécies de Anopheles em região de 430 km de extensão.

Studies have been un dertaken into on the diversity and relative abundance of larvae of Anopheles (Nyssorhynchus) spp. in 22 permanent or temporary pools in an area of 70 km² in the eastern piedmont of the Venezuela Andes, between the mountains and the plains, an area in which malaria is refractory and A. nuñeztovari is present. Twelve species were identified, the most frequent, abundant and sympatric being A. triannulatus, A. albitarsis, A. nuñeztovari, A. oswaldoi and A. strodei. The samples from the permanent pools showed greater diversity of species and greater numbers of larvae than the samples from the temporary pools. The existence of the same larval associations in pools of other localities in the eastern piedmont of the Venezuelan Andes suggests the possibility of the making an ecological map of the breeding sites of A. nuñeztovari and for these anophelines in a region extending for 430 km.

Tem-se estudado a diversidade e a riqueza de larvas de Anopheles (Nyssorhynchus) spp. em 22 postos permanentes e temporais em área de 70 km² ao pé da Cordilheira Andina Oriental da Venezuela, em região de malária refratária. Foram identificadas 12 espécies, sendo as mais freqüentes, abundantes e simpátricas as A. triannulatus, A. albitarsis, A. nuñeztovari, A. oswaldoi y A. strodei. Foi maior o número de espécies e de larvas por amostra nos postos permanentes do que nos temporais. A existência das mesmas associações larvais, em postos de outras localidades, ao pé da Cordilheira Andina Oriental da Venezuela, baseia-se no ponto de vista de que é possível fazer-se um mapa ecológico dos criadouros dessas espécies de Anopheles em região de 430 km de extensão.

Studies have been un dertaken into on the diversity and relative abundance of larvae of Anopheles (Nyssorhynchus) spp. in 22 permanent or temporary pools in an area of 70 km² in the eastern piedmont of the Venezuela Andes, between the mountains and the plains, an area in which malaria is refractory and A. nuñeztovari is present. Twelve species were identified, the most frequent, abundant and sympatric being A. triannulatus, A. albitarsis, A. nuñeztovari, A. oswaldoi and A. strodei. The samples from the permanent pools showed greater diversity of species and greater numbers of larvae than the samples from the temporary pools. The existence of the same larval associations in pools of other localities in the eastern piedmont of the Venezuelan Andes suggests the possibility of the making an ecological map of the breeding sites of A. nuñeztovari and for these anophelines in a region extending for 430 km.

Two lots of 20 young male guinea pigs were inoculated subcutaneously in the tarsi with 10 (elevated to fourth potency) amastigotes of Leishmania braziliensis or L. b. guyanensis to study the susceptibility of this Neotropical hystricomorph rodent the autochthonous parasites. Almost 50% of the animals showed lesions in the inoculation site and had parazitations that were infective to hamsters, as shown by inoculating homogenates of the dermal lesion, of the spleen, of the liver, and of the nasal mucosa into hamsters at 20, 40, 60 and 120 days after inoculation of the guinea pig. Smears of the above organs showed the presence of amastigotes. Parasites inoculated into the tarsi were detected early in the skin, spleen, and liver of the guinea pig host. Blood cultures made by cardiopuncture on sacrifice of the guinea pigs were uniformly negative. The nasal mucosa of nearly all animals positive in the skin or viscera was invaded early by the parasites, although with grater frequency between 60 and 120 days post-inoculation. The use of this model for the study of mucocutaneous parasitism by L. brasiliensis is discussed, together with the phenomena of parasitism at a distance from the inoculation site, the temperature of the body regions affected, and the possible genetic influence on susceptibility of the guinea pig to L. brasiliensis.

Lutzomyia townsendi (Ortiz, 1959) is the main anthropophilic sandfly in endemic places for Leishmania braziliensis and L. garnhami in Western Venezuela. The study of laboratory bred females, nulliparous or parous and, wild females fed on man as well as wild females maintained with sucrose, allowed to establish a criterion of nulliparity with 56.6% of confidence for those captured in field conditions. In the same wild females, parity can be assessed with 81.5% of confidence. After blood digestion of full-engorged females a gonotrophic cycle is completed. Abortive oogenesis and accumulation of phospholipids in midgut epitelial cells and into accessory glands are observed. The ovoposition produces a thick and irregular ovaric calix with rests of abortive oocytes and accumulation of a melanin-like black pigment. All these changes are enough for identification of a parous fly. The presence of phospholipids in the stomach and accessory glands of a nulliparous sandfly is indicative of digestion of an incomplete blood meal.

Lutzomyia townsendi (Ortiz, 1959) es un flebótomo antropofílico con concordancia gonadotrófica, en las zonas endémicas de Leishmania brasiliensis y L. garnhami en el occidente de Venezuela. Mediante el estudio de hembras colonizadas en el laboratorio, nuliparas o paridas, de hembras silvestres alimentadas sobre voluntarios y de hembras silvestres mantenidas con sacarosa, se establecen criterios de nuliparidad con un 56,6% de confianza. En cambio, signos de paridad aparecen en un 82% de las hembras consideradas como tales. La digestión de un ingesta sanguínea inicia un ciclo gonadotrófico con oogénesis abortiva y acumulación de fosfolípidos en las células epiteliales del estómago y en las glândulas accesorias. La ovoposición completa produce un calix ovárico grueso e irregular con restos de oocitos abortivos y acumulación de pigmentos. Estos caracteres son suficientes para precisar un criterio de paridad. La presencia de fosfolípidos en el estómago y en las glândulas accesorias de hembras nulíparas es una indicación de ingesta incompleta de sangre.