RESUMO
BACKGROUND & OBJECTIVES: Trypanosoma cruzi and Leishmania spp. are protozoans that cause American trypanosomiasis and leishmaniasis, respectively. In endemic foci where both diseases coincide, coinfection can occur. The objective of this work was the characterization of the parasites involved in coinfection in several endemic areas of Venezuela. METHODS: Molecular characterization was done in 30 samples of several species of mammals (Didelphis marsupialis, Equus mulus, Rattus rattus, Canis familiaris, Felis catus, and Sciurus granatensis) from the states of Anzoategui, Cojedes and Capital District diagnosed with T. cruzi and Leishmania spp. coinfections. For the typing of T. cruzi DTUs, the markers of miniexon, 24Sa rDNA, 18Sa rDNA, and hsp60-PCR-RFLP (EcoRV) were used. Infection by Leishmania spp. was characterized by miniexon multiplex PCR for complexes of Leishmania and ITS1-PCR-RFLP (HaeIII, HhaI, and RsaI) for the identification of the species. RESULTS: The T. cruzi TcI was present in 100% of the coinfected mammals, which included 76.7% of triple infection by T. cruzi TcI-complex-L. (L) mexicana-L. infantum/chagasi, 13.3% of double infection by T. cruzi TcI-L. mexicana and 10% of double infection by T. cruzi Tcl-L. infantum/chagasi. INTERPRETATION & CONCLUSION: These results suggest that the double or triple infection is a phenomenon existing in almost all the coendemics areas and mammals studied, which might influence the mechanisms of adaptation and pathogenicity of these parasites.
Assuntos
Doença de Chagas/veterinária , Coinfecção/epidemiologia , Leishmania/genética , Leishmaniose/veterinária , Mamíferos/parasitologia , Trypanosoma cruzi/genética , Animais , Animais Selvagens/parasitologia , Doença de Chagas/epidemiologia , Coinfecção/parasitologia , DNA de Protozoário/genética , Reservatórios de Doenças/parasitologia , Doenças Endêmicas , Leishmaniose/epidemiologia , Venezuela/epidemiologiaRESUMO
This study reports cutaneous leishmaniasis (CL) caused by Leishmania chagasi/Le. infantum in Venezuela, with some atypical characteristics. Out of 63 cases of CL in the suburbs of Altagracia de Orituco, Guarico State, Venezuela, 30 presented clinical, parasitological, immunological and epidemiological features different from those of the classical CL known in the country. The initial lesion was small and nodular, which, if not treated, might progress to a superficial ulcer. No secondary infection was observed. The identification of the isolates was carried out by molecular techniques. Twelve species of phlebotomine sandflies were caught, the most abundant being Lutzomyia evansi and Lu. longipalpis s.l., known vectors of Le. chagasi/Le. infantum. The existence of Le. chagasi/Le. infantum and its vectors in an endemic area of CL has implications and we suggest that epidemiological studies should be carried out to obtain a clearer picture of the extent of this CL form in Venezuela.
Assuntos
Leishmania donovani/isolamento & purificação , Leishmania infantum/isolamento & purificação , Leishmaniose Cutânea/parasitologia , Adolescente , Adulto , Animais , Feminino , Humanos , Leishmaniose Cutânea/epidemiologia , Masculino , Reação em Cadeia da Polimerase , Psychodidae/parasitologia , Especificidade da Espécie , Venezuela/epidemiologia , Adulto JovemRESUMO
Natural infection with Leishmania spp. in phlebotomine sandflies was searched for during a longitudinal study carried out from July 1997 to July 1998 in the village Catarnica, Municipality Independencia, Táchira State. This hamlet is an old endemic focus of cutaneous leishmaniasis in the Venezuelan Andean region, which lies close to the Colombian border at 1,300 m a.s.l., in an agricultural area mainly used for cultivating coffee. Phlebotomine sandflies were collected using Shannon traps placed in the peridomestic habitat from 19:00 to 21:00 hs. Males were stored in alcohol 70 % while females were kept in Nunc vials with 10 % DMSO and cryopreserved in liquid nitrogen for subsequent dissection and identification. The most abundant anthropophilic species was Lutzomyia spinicrassa with 3,032 males and 4,290 females (85.4%). Among 1,633 (38%) females of Lu. spinicrassa dissected, 26 11.6%) were infected with promastigotes, while no natural infection was found in 209 females of other species. The flagellates were identified as Leishmania braziliensis braziliensis using PCR with species specific primers derived from nuclear DNA and hybridization using species specific probe labelled with digoxigenin. This parasite had been previously isolated from patients with cutaneous leishmaniasis from the same area. These results show Lu. spinicrassa as a new proven vector of Leishmania braziliensis in the Andean region of Venezuela.
Assuntos
DNA de Protozoário/análise , Insetos Vetores/parasitologia , Leishmania braziliensis/isolamento & purificação , Psychodidae/parasitologia , Animais , Feminino , Humanos , Leishmania braziliensis/genética , Leishmaniose Cutânea/epidemiologia , Leishmaniose Cutânea/transmissão , Leishmaniose Tegumentar Difusa/epidemiologia , Leishmaniose Tegumentar Difusa/transmissão , Leishmaniose Mucocutânea/epidemiologia , Leishmaniose Mucocutânea/transmissão , Masculino , Reação em Cadeia da Polimerase , Especificidade da Espécie , Venezuela/epidemiologiaRESUMO
Leishmania infantum has been described as a highly polymorphic group of parasites, responsible for visceral leishmaniasis and cutaneous leishmaniasis. In this paper we report the life-cycle of L. (L.) infantum in an endemic area of visceral leishmaniasis in Venezuela, by using molecular diagnosis and characterization of parasites isolated from dogs, humans with visceral leishmaniasis and sand flies. The molecular characterization was carried out by use of kDNA restriction analysis, dot-blot hybridization with species-specific probes and RFLP of the PCR products. The results demonstrated that L. (L.) infantum is the parasite responsible for VL in the island. The parasites were revealed to be genetically homogeneous with no intra-specific differences between isolates from different individuals. The highest homology of the isolates was with L. (L.) infantum from the Old World rather than with L. (L.) chagasi from the New World. Additionally, we report the geographical distribution of Lutzomyia longipalpis, and the relationship with the transmission of L. (L.) infantum in the studied area.
Assuntos
Variação Genética , Leishmania infantum/genética , Psychodidae/parasitologia , Animais , Cães , Ecossistema , Humanos , Leishmania infantum/isolamento & purificação , Leishmaniose Visceral/parasitologia , Leishmaniose Visceral/transmissão , VenezuelaRESUMO
The nocturnal activity of the phlebotomine sandfly Lutzomyia pseudolongipalpis and two populations of L. longipalpis s.l. from different American visceral leishmaniasis foci in Venezuela was studied using collection bottle rotator traps. The activity of L. pseudolongipalpis from Lara State was continuous throughout the night, while that of L. longipalpis s.l. from El Layero, Guárico State and from Santa Ana del Valle, Margarita Island, was greatest before 23:00 h. The activity of sandflies of both populations and sexes steadily decreased thereafter. These different patterns seem to correlate with genetic data that indicate the presence in Venezuela of at least two sibling species in the L. longipalpis complex. The advantages of the bottle rotator trap for this type of study are discussed.
Assuntos
Insetos Vetores/fisiologia , Psychodidae/fisiologia , Animais , Ritmo Circadiano , Feminino , Controle de Insetos/instrumentação , Leishmaniose Visceral/transmissão , Masculino , Vigilância da População , Razão de Masculinidade , VenezuelaRESUMO
Methods of finding larvae and pupae of phlebotomine sandflies (Diptera: Psychodidae) are described and the known types of breeding sites used by sandflies are listed. Three ways of detecting sandfly breeding places are the use of emergence traps placed over potential sources to catch newly emerged adult sandflies; flotation of larvae and pupae from soil, etc., and desiccation of media to drive out the larvae. Even so, remarkably little information is available on the ecology of the developmental stages of sandflies, despite their importance as vectors of Leishmania, Bartonella and phleboviruses affecting humans and other vertebrates in warmers parts of the world. Regarding the proven or suspected vectors of leishmaniases, information on breeding sites is available for only 15 out of 29 species of sandflies involved in the Old World and 12 out of 44 species of sandflies involved in the Americas, representing approximately 3% of the known species of Phlebotominae. Ecotopes occupied by immature phlebotomines are usually organically rich moist soils, such as the rain forest floor (Lutzomyia intermedia, Lu. umbratilis, Lu. whitmani in the Amazon; Lu. gomezi, Lu. panamensis, Lu. trapidoi in Panama), or contaminated soil of animal shelters (Lu. longipalpis s.l. in South America, Phlebotomus argentipes in India; P. chinensis in China; P. ariasi, P. perfiliewi, P. perniciosus in Europe). Developmental stages of some species (P. langeroni and P. martini in Africa; P. papatasi in Eurasia; Lu. longipalpis s.l. in South America), have been found in a wide range of ecotopes, and many species of sandflies employ rodent burrows as breeding sites, although the importance of this niche is unclear. Larvae of some phlebotomines have been found in what appear to be specialized niches such as Lu. ovallesi on buttress roots of trees in Panama; P. celiae in termite hills in Kenya; P. longipes and P. pedifer in caves and among rocks in East Africa. Old World species found as immatures in the earthen floor of human habitations include P. argentipes, P. chinensis, P. martini and P. papatasi. Much more information on sandfly breeding sites is required to facilitate their control by source reduction.
Assuntos
Ecossistema , Phlebotomus/crescimento & desenvolvimento , Animais , Insetos Vetores/crescimento & desenvolvimento , Insetos Vetores/parasitologia , Leishmania/crescimento & desenvolvimento , Leishmaniose/epidemiologia , Leishmaniose/transmissão , Phlebotomus/parasitologiaRESUMO
Sand flies in the Lutzomyia longipalpis species complex include the primary vector of Leishmania chagasi, the etiologic agent of visceral leishmaniasis in the Neotropics. Twelve L. longipalpis populations from South and Central America were compared using the cytochrome c oxidase I (COI) gene from the mitochondrial genome. The haplotype profiles for each population revealed that the majority of sequence variation was inter-population (98%) rather than intra-population, suggesting that sequence polymorphisms at the COI locus should provide excellent characters for the study of phylogenetic relationships among populations. Phylogenetic reconstruction using distance (neighbor-joining) and maximum parsimony analysis revealed the existence of four clades among the L. longipalpis populations studied: (1) Laran, (2) Brazilian, (3) cis-Andean and (4) trans-Andean. We suggest that these clades represent species. A biogeographical interpretation of the molecular phylogeny suggests that the process of speciation in the L. longipalpis complex began in the Pliocene, from a sub-Andean-Amazonian gene pool resulting from the Andean orogeny (formation of the East Andean Cordillera). The four clades probably diverged as a result of vicariance events that occurred throughout the late Pliocene and Pleistocene. We propose and discuss several historical scenarios, based on the biogeography and historical geology of Central and South America.
Assuntos
DNA Mitocondrial , Geografia , Filogenia , Psychodidae/genética , Animais , Sequência de Bases , América Central , Variação Genética , Haplótipos , Dados de Sequência Molecular , América do SulRESUMO
The existence of Rhodnius robustus as a species distinct from Rhodnius prolixus has long been the main epidemiological question about Chagas disease transmission in Venezuela and surrounding countries. These two taxa are morphologically and genetically very similar, but only R. prolixus is assumed to colonize houses and transmit Chagas disease to humans. R. robustus is assumed to be an exclusively sylvatic species, restricted to palm trees. If robustus and prolixus are actually the same species, the theoretical possibility exists of sylvatic specimens invading houses, even after insecticide application, and a control strategy similar to that of the successful Southern Cone Initiative against Triatoma infestans would be difficult to consider. Since no valid alternative control strategy exists, the answer to this biological question could be decisive about the future of vector control in this region. Although we believe genetic techniques are best suited to define species boundaries, we present here an example of the relevance of modern morphometrics in dealing with such an issue. Using both traditional and geometric morphometrics, we compared the wing size and shape in both sexes of these two taxa reared in the same laboratory for one generation. R. robustus specimens were collected from palm trees in the state of Mérida (Venezuela), and R. prolixus were collected from houses in the state of Cojedes (Venezuela). Our study provided no argument to question their specific status. Even after one generation of living in the same laboratory conditions, the two lines showed clear size differences, divergent allometric trends, and significant allometry-free differences in shape. These results suggest that R. robustus (Mérida, Venezuela) and R. prolixus (Cojedes, Venezuela) are distinct evolutionary units. Due to the epidemiological importance of this question, further studies in other geographic areas of Venezuela are required to accurately define the relationships of R. robustus and R. prolixus.
Assuntos
Rhodnius/anatomia & histologia , Asas de Animais/anatomia & histologia , Animais , Variação Genética , Rhodnius/classificação , Rhodnius/genéticaRESUMO
Recently collected data on the Venezuelan species of the genus Brumptomyia are used to produce an updated review of these sandflies. At present, four species are recognized in Venezuela: B. devenanzii, B. beaupertuyi, B. avellari and B. pintoi. A key for the males is given and the geographical distribution of each of these species is outlined. The previously unknown female of B. devenanzii is described, the male is re-described, and the genetic variability (based on 11 enzymatic loci) of this species and of B. beaupertuyi (a sympatric species in Rancho Grande, the type locality of B. devenanzii) are reported. Fixed allelic differences in one diagnostic locus (adenylate kinase; Ak), between sympatric and allopatric populations, allowed for the unequivocal separation of both sexes of B. beaupertuyi from those of B. devenanzii. Significant inter-specific differences were also detected in the allele frequencies of malate dehydrogenase (Mdh-2) and decarboxylating malate dehydrogenase (Me). For B. devenanzii, mean heterozygosity and mean number of alleles per locus ranged from 2.0%-3.1% and 1.1-1.5, respectively. The corresponding values for B. beaupertuyi were 3.8% and 1.2.
Assuntos
Psychodidae/anatomia & histologia , Adenilato Quinase/genética , Alelos , Animais , Eletroforese em Gel de Poliacrilamida , Feminino , Variação Genética , Heterozigoto , Humanos , Isoenzimas/genética , Malato Desidrogenase/genética , Masculino , Fenótipo , Psychodidae/enzimologia , Psychodidae/genéticaRESUMO
Predictions that deforestation would reduce American cutaneous leishmaniasis incidence have proved incorrect. Presentations at a recent international workshop, instead, demonstrated frequent domestication of transmission throughout Latin America. While posing new threats, this process also increases the effectiveness of vector control in and around houses. New approaches for sand fly control and effective targeting of resources are reviewed.