Susceptibility of laboratory-reared female Lutzomyia longipalpis (Lutz & Neiva, 1912) to infection by different species and strains of Leishmania Ross, 1903

A study was undertaken to compare the susceptibility of laboratory-reared female Lutzomyia longipalpis to infection by different species or strains of New World Leishmania. The sand flies proved to be highly susceptible to infection by a strain of Le. guyanensis, with flagellates developing in all (18/18) of the specimens examined. A lower infection rate of 37 per cents (10/27) was recorded in flies exposed to infection by a strain of Le. amazonensis. Flagellates developed in 13 per cents (6/46) of the sand flies that glood fed on dogs in the earlly stage of experimental infection with an old laboratory strain of Le. chagasi. In contrast, promastigotes did not develop in sand flies that blood fed on dogs with naturally acquired Le. chagasi. The naturally infected dogas were in an advanced stage of disease. Flagellates developed in 9// (3/32) of the sand flies that blood fed on lesions of hamsters infected with a strain of Le. braziliensis and in 9 per cents (3/34) of those that fed on hamsters with lesions due to a parasite fo the mexicana complex (strain MHOM/BR/73/BH121). Sand flies did not develop flagellate infections after blood feeding on hamsters bearing lesions induced by strain MHOM/BR/71/BR49. Factors influencing the susceptibility of Lu. longipalpis to infection by New World species of Leishmania are discussed.

Development of Leishmania (Viannia) braziliensis Vianna, 1911 in Lutzomyia intermedia (Lutz & Neiva, 1912) (Diptera: Psychodidae: Phlebotominae) under experimental conditions

The development of Leishmania (Viannia) braziliensis in experimentally infected Lutzomyia intermedia, showed colonization of the hindgut from 48h after the infective blood-meal, and the migration flagellates to the foregut, with a massive infection of the cardia at the 5th day post infection. Up to 10 days following the infective blood-meal, very few parasites were seen in the pharynx and cibarium. The role of L. intermedia as a vector of cutaneous leishmaniasis is discussed according to the estabilished criteria.

Development of Colombian isolates of Leishmania (Viannia) panamensis, Le. (V.) guyanensis and Le. (V.) braziliensis in the sandfly Lutzomyia intermedia (Lutz & Neiva, 1912) under experimental conditions

The development of Colombian Leishmania species of the subgenus Viannia in Lutzomyia intermedia was similar to that observed with Brazilian Le. (V.) braziliensis: colonization of the pylorus by paramastigotes; promastigotes in the midgut and massive infection of stomodeal valve. Difference was observed in the number of paramastigotes colonizing the pylorus, which was smaller in Colombian Leishmania species than Brazilian Le. braziliensis.

The development of species of Leishmania Ross, 1903 in Lutzomyia longipalpis (Lutz & Neiva, 1912)

The development of four isolates of Leishmania from foci of American cutaneous leishmaniasis was studied in Lutzomyia longipalpis. The suggestion that the differences in the development of the Leishmania in the invertebrate host are of great taxonomic significance was confirmed. The pattern of development of three strains was typical of parasites of the subgenus Leishmania, the other was similar to Leishmania of the subgenus Viannia. The identification of the strains using other criteria is in agreement with biological characterization. The results show that the morphological and morphometric study of promastigotes do not clearly define the taxonomic position of the parasites but other studies are needed to confirm this.

El concepto de extrañeza en Albert Camus

Aquest treball indaga en la noció d'estranyesa en l'obra d'Albert Camus (1913-1960), escriptor, filòsof, periodista, dramaturg i Premi Nobel de Literatura. En un recorregut per la novel·la L’estranger, i per altres volums de l'escriptor algerià, es tracen les línies fonamentals del pensament d'aquest autor, considerat un artífex de l'existencialisme, etiqueta que ell mateix rebutjaria. En aquesta investigació es realitza una inspecció a la seva trajectòria per a dilucidar si l'absurd camusià és un pas al nihilisme o si, al contrari, l'estranyesa serà una via per superar-lo.

Infection of Oxydoras kneri Bleecker, 1862 (Pisces, Doradidae) by the acanthocephalan Paracavisoma impudica (Diesing, 1851) Kritcher, 1957

Infection of Oxydoras kneri by the acanthocephalan Paracavisoma impudica is described. The parasites do not penetrate deeply into the host gut wall and do not reach the muscularis layers. Host reaction is minimal, consisting of limited fibrosis around the proboscides. Haemorrhages and lymphocyte infiltration are not observed, and phagocytic cells are only present occasionally. Oxydoras kneri is a newly reported host for Paracavisoma impudica.

The influence of sugars and amino acids on the blood-feeding behaviour, oviposition and longevity of laboratory colony of Lutzomyia longipalpis (Lutz & Neiva, 1912) (Diptera: Psychodidae, Phlebotominae)

Schneider's Drosophila medium, a complex amino acid rich medium was tested alone and with seven different sugars for some aspects of the biology of Lutzomyia longipalpis. Statistically significant results were obtained when sucrose was used alone, indicating that among the sugars tested, this is still the most suitable and practical one for the maintenance of L. longipalpis colonies. However, the addition of Schneider's medium to a pool of different sugars, was suggested to be related with the acceptance of the first and second blood meals and to longevity, these being, obviously, quite relevant aspects when tansmission experiments are contemplated.

A Redescription of Lutzomyia (Nyssomyia) intermedia (Lutz & Neiva, 1912), and Resurrection of L. neivai (Pinto, 1926) (Diptera, Psychodidae, Phlebotominae)

Lutzomyia (Nyssomyia) intermedia (Lutz & Neiva) is redescribed, a neotype is designated, and a very similar species, L. (N.) neivai (Pinto, 1926), is resurrected; the male and the female are redescribed. The two species can be differentiated by differences in the spermathecae, common ducts and number of cibarial horizontal teeth of the females and in the size and proportions of several structures of both sexes. The known geographical distribution of both species is given.

Genetic Variation among Natural and Laboratory Colony Populations of Lutzomyia longipalpis (Lutz & Neiva, 1912)(Diptera:Psychodidae) from Colombia

Genetic diversity among three field populations of Lutzomyia longipalpis in Colombia was studied using isozyme analysis. Study sites were as much as 598 km apart and included populations separated by the eastern Cordillera of the Andes. Genetic variability among populations, estimated by heterozygosity, was within values typical for insects in general (8.1%). Heterozygosity for field populations were compared with a laboratory colony from Colombia (Melgar colony) and were only slightly lower. These results suggest that establishment and long term maintenance of the Melgar colony has had little effect on the level of isozyme variability it carries. Genetic divergences between populations was evaluated using estimates of genetic distance. Genetic divergence among the three field populations was low (D=0.021), suggesting they represent local populations within a single species. Genetic distance between field populations and the Melgar colony was also low (D=0.016), suggesting that this colony population does not depart significantly from natural populations. Finally, comparisons were made between Colombian populations and colonies from Brazil and Costa Rica. Genetic distance values were high between Colombian and both Brazil and Costa Rica colony populations (D=0.199 and 0.098 respectively) providing additional support for our earlier report that populations from the three countries represent distinct species

Influence of altitude, latitude and season of collection (Bergmann's Rule) on the dimensions of Lutzomyia intermedia (Lutz & Neiva, 1912) (diptera, psychodidae, phlebotominae)

The influence of altitude and latitude on some structure sizes of Lutzomyia intermedia was noted; several structures of insects collected in higher localities were greater, according to Bergmann's rule. This influence was more remarkable in two localities of the State of Espírito Santo, probably due to greater differences in altitude. Comparing insects from different latitudes, more differences were noted in comparisons of insects from low altitude localities than in those of material from higher altitudes. The small number of differences between insects collected in July and in December does not indicate a defined influence of season and temperature on the size of adults. The possible epidemiological implications of these variations are discussed.

Studies on populations of Lutzomyia longipalpis (Lutz & Neiva, 1912) (Diptera: Psychodidae: Phlebotominae) in Brazil

Studies were performed on five Brazilian populations of Lutzomyia longipalpis: Salvaterra (PA), São José do Ribamar (MA), Canindé (CE), Natal (RN) and Gruta da Lapinha, Lagoa Santa (MG). No morphological differences were observed that could distinguish between these populations. Homogeneity tests showed that the allopatric populations display a certain heterogeneity and that the sympatric populations, with different patterns of spots, are homogeneous. The Student-Newman-Keuls test, represented by Euler-Venn diagrams, showed a disjunction between the populations from the north/northeast and the one from Gruta da Lapinha. Genetic distances between the four populations (excluding the Canindé population) were within the range of intrapopulational differences. The Gruta da Lapinha population displayed a heterozygotic deficiency that could be a consequence of high levels of inbreeding due to cryptic habits of living in a small cave. These results do not favor the hypothesis of a L. longipalpis species complex in Brazil, and the species should be considered high polymorphic.