We analyzed 64 quantitative and qualitative morphological characters in different populations of Lutzomyia (Nyssomyia) umbratilis Ward & Fraiha from Venezuela (Gran Sabana, Bolívar/BO) and Brazil ...(Serra do Navio, Amapá/AP, Manaus, Amazonas/AM, Monte Dourado, Pará/PA, and Peixoto de Azevedo, Mato Grosso/MT). Based on an analysis of qualitative characters, no differences were observed that could distinguish between the populations. Parametric tests were used to verify differences between sample means and variance homogeneity. The analysis-of-variance (ANOVA) test showed the existence of differences between character means in the five populations. In the graphic representation of the Student-Newman-Keuls test (Student–Newman–Keuls), we observed that 77% of the analyzed characters displayed disjunctions between the Venezuelan and Brazilian populations. Considering only the Brazilian population averages, we concluded that they are statistically different. When the Student–Newman–Keuls test was applied, no pattern was found that could separate them. However, in part, the phenetic analysis showed some evidences of heterogeneity in MT population.
Leishmania isolated from the digestive tract of a naturally infected Lutzomyia ovallesi sand fly were cultured in blood agar for rapid growth, cloning, and subsequent identification through ...schizodeme analysis, dot-blot hybridization, use of monoclonal antibodies with various specificities and absorbed polyclonal antibodies. Twenty-three clones isolated from the primary culture were identified. The results showed that parasites belonging to some clones corresponded to the L. mexicana complex, while others belonged to the L. braziliensis complex. These results clearly establish the coexistence of two Leishmania species in the digestive tract of a single Lu. ovallesi sand fly.
The comparative hourly activity of Lutzomyia ovallesi (Ortiz) and L. gomezi (Nitzulescu), vectors of cutaneous leishmaniasis in Miranda State, Venezuela, was studies between November and March during ...1991-1994 using a Shannon trap with a fluorescent light. Female abundance of L. ovallesi increased from 1800 to 2000 hours, plateaued from 2000 to 2400 hours, then decreased progressively. L. gomerzi always exhibited maximum activity between 1900 and 2000 hours, then declined abruptly. The importance of these activity patterns in Leishmania transmission is discussed
Chagas disease is an endemic zoonosis native to the Americas and is caused by the kinetoplastid protozoan parasite Trypanosoma cruzi. The parasite is also highly genetically diverse, with six ...discrete typing units (DTUs) reported TcI - TcVI. These DTUs broadly correlate with several epidemiogical, ecological and pathological features of Chagas disease. In this manuscript we report the most comprehensive evaluation to date of the genetic diversity of T. cruzi in Venezuela. The dataset includes 778 samples collected and genotyped over the last twelve years from multiple hosts and vectors, including nine wild and domestic mammalian host species, and seven species of triatomine bug, as well as from human sources. Most isolates (732) can be assigned to the TcI clade (94.1%); 24 to the TcIV group (3.1%) and 22 to TcIII (2.8%). Importantly, among the 95 isolates genotyped from human disease cases, 79% belonged to TcI - a DTU common in the Americas, however, 21% belonged to TcIV- a little known genotype previously thought to be rare in humans. Furthermore, were able to assign multiple oral Chagas diseases cases to TcI in the area around the capital, Caracas. We discuss our findings in the context of T. cruzi DTU distributions elsewhere in the Americas, and evaluate the impact they have on the future of Chagas disease control in Venezuela.
Some evidence suggests that bats may provide an alternative blood source for Lutzomyia longipalpis, the main vector of American visceral leishmaniasis. Feeding trials were conducted to determine ...whether L. longipalpis feeds on captive bats. The high feeding success indicated that L. longipalpis is capable of feeding on at least four species of bats. Implications for the epidemiology of leishmaniases are discussed.
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 and Hoyos, and L. youngi Feliciangeli and 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
As part of an epidemiological study in an old focus of American Visceral Leishmaniasis (AVL) in Venezuela (Guayabita, Aragua State, a longitudinal entomological survey (January 1993-June 1994) was ...carried out. A total of 3,239 males and 6,043 females belonging to 11 phlebotomine sandfly species were collected. The two recognised vectors of AVL in the New World, Lutzomyia evansi and Lu. longipalpis were found to be sympatric. Lutzomyia evansi was the dominant species (86.4 %), almost ten fold times more abundant than Lu. longipalpis (10.6 %). The two species alternated seasonally: Lu evansi peaked at the end of the rainy season while Lu. longipalpis, almost virtually absent during such period, increased in the dry season. This species seems more greatly influenced by the temperature. Seven of 4,559 Lutzomyia evansi (0.15 %) and one of 353 Lu. longipalpis (0.28 %) were found positive for suprapyloric promastigotes. Using the polymerase chain reaction (PCR) with universal primers, all isolates were identified as Leishmania spp. Two cultures from Lu. evansi, IEVA/VE/93/UCNA-2 and IEVA/VE/93/UCNA-3, were established. k-DNA restriction analysis showed high homologies between these isolates and Leishmania chagasi. High hybridization signal with Í. chagasi specific kDNA confirmed these results. These findings suggest that Lu. evansi may play a role as vector of visceral leishmaniasis in this area. The identity of the parasite carried by Lu. longipalpis needs to be confirmed.
Une étude entomologique longitudinale janvier 1993-juin 1994) a été réalisée dans le village de Guayabita, État Aragua, un foyer ancien de leishmaniose viscérale du centre-nord du Vénézuela (10°16'N, 67°28'W; 500 m). Au total, 3239 mâles et 6043 femelles appartenant à 11 espèces de phlébotomes ont été capturés en utilisant des pièges CDC et Shannon. Lutzomyia evansi et Lu. longipalpis, les deux espèces reconnues comme vecteurs de leishmaniose viscérale dans le Nouveau Monde ont été rencontrées en sympatrie dans ce foyer. Lutzomyia evansi prédomine nettement (86,4 %) sur Lu. longipalpis (10,6 %). Les deux espèces se succèdent selon la saison : Lu, evansi domine à la fin de la saison des pluies alors que Lu. longipalpis, virtuellement absent à cette époque de l'année, augmente à la saison sèche; cette espèce serait fortement influencée par la température. Sept exemplaires sur 4559 Lutzomyia evansi 10, 15 %) et un spécimen sur 353 Lu. longipalpis (0,28 %) étaient naturellement infectés par des promastigotes suprapyloriques. En utilisant la PCR avec des amorces universelles, toutes les souches isolées ont été identifiées comme Leishmania spp. La multiplication des parasites à partir du tube digestif de deux Lu. evansi, IEVA/VE/93/UCNA-2 et IEVA/VE/93/UCNA-3 a été obtenue. L'analyse de restriction du k-DNA a montré une grande homologie entre les souches isolées et Leishmania chagasi. Un haut signal d'hybridation avec kDNA spécifique de Le. chagasi a confirmé ces résultats qui ont permis de conclure au rôle vecteur de Lu. evansi dans ce foyer. L'identité du parasite transporté par Lu. longipalpis doit être confirmée
An endemic focus of American visceral leishmaniasis (AVL) in eastern Venezuela has been evaluated in terms of patients (n = 48), immunologic reactivity to Leishmania in household contacts (n = 187) ...and neighborhood controls (n = 170), detection of Leishmania (L. donovani complex) in dogs and wild animals by the polymerase chain reaction (PCR) and characteristics of the sandfly population. The male:female ratio of patients was 1.18:1; 89.6% were < or =12 years old. Serologic reactivity was significantly higher in household contacts than in controls (P = 0.0008), as was the size of leishmanin reactions in contacts < or =10 years of age (P = 0.0141). Leishmania donovani complex-specific PCRs were positive in dogs, an opossum (Didelphis marsupialis), and a black rat (Rattus rattus). Lutzomyia longipalpis and Lu. evansi, both implicated in the transmission of AVL, were identified among the 386 sand flies examined. These observations provide the bases for an active control program as well as further studies of reservoirs and vector-host relationships in this area.
A laboratory trial using recombinant rK39 dipsticks for differential diagnosis of American visceral leishmaniasis (AVL) from other sympatric endemic diseases which share similar clinic features ...(Chagas disease, malaria, schistosomiasis and toxoplasmosis) was conducted in Venezuela. The 100 % specificity of the test previously obtained in other countries was confirmed. The use of this test at the primary health care level in Venezuela for a rapid diagnosis of active AVL cases, which may avoid deaths, is recommended.
Une étude utilisant des bandelettes imprégnées d'antigène recombinant rK39 a été menée en laboratoire pour le diagnostic différentiel de la leishmaniose viscérale des autres maladies endémiques au Venezuela présentant des similitudes cliniques (maladie de Chagas, paludisme, schistosomiase, toxoplasmose). La spécificité du test (100 %), déjà observée dans d'autres études, a été confirmée. L'utilisation de ce test au niveau des soins de santé primaires est recommandée pour un diagnostic précoce de la leishmaniose viscérale américaine.
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