Report of Lutzomyia longipalpis (Lutz & Neiva, 1912) (Diptera: Psychodidae: Phlebotominae) in a cutaneous-leishmaniasis-endemic area of Panama

Lutzomyia longipalpis is the primary vector of the parasite responsible for visceral leishmaniasis in the Americas. In the present study, Lu. longipalpis was found in a domiciliary area in Limón, a district in Capira, a region in which cutaneous leishmaniasis is endemic in Panama. Previously, this species has been found in a humid forest in this same region. Finding Lu. longipalpis in domiciliary areas indicates that this species may be adapting to new habitats and that it may play a role in the transmission of leishmaniasis in Panama.     

Lutzomyia longipalpis in Brazil: a complex or a single species? A mini-review

Lutzomyia longipalpis is the main vector of Leishmania infantum chagasi, the causative agent of American visceral leishmaniasis (AVL). Although there is strong evidence that Lu. longipalpis is a species complex, not all data concerning populations from Brazil support this hypothesis. The issue is still somewhat controversial for this large part of Lu. longipalpis distribution range even though that it is the Latin American region contributing to most of the cases of AVL. In this mini-review we consider in detail the current data for the Brazilian populations and conclude that Lu. longipalpis is a complex of incipient vector species with a complexity similar to Anopheles gambiae s.s. in Africa.     

Speciation and population structure in the morphospecies Lutzomyia longipalpis (Lutz & Neiva) as derived from the mitochondrial ND4 gene

Recent studies have suggested that the phlebotomine sand fly Lutzomyia longipalpis (Diptera: Psychodidae), the principal vector of visceral leishmaniasis in the Neotropics, may consist of several allopatric sibling species. Phylogenetic and population genetic analyses of nucleotide variation in a 618-bp fragment of the mitochondrial ND4 gene were carried out on specimens of Lu. longipalpis from several locations in Central and South America. The analyses were concordant with previous findings, indicating that certain allopatric populations of Lu. longipalpis have become sufficiently differentiated as to represent sibling species. Phylogenetic analyses revealed deep genetic divisions between four clades represented by specimens from northern South America, Brazil, Central America, and an isolated Colombian population. Strong differentiation also was observed between certain populations within the first two clades. Partitioning of genetic diversity within and between Central American populations did not show the presence of more than one species in the region. However, distance, even within the 70-km range of the Honduran collection sites, was found to have a remarkably strong effect on gene flow. The highly subdivided population structure may be due to the patchiness of their distribution. F(ST) values comparing a Guatemalan population with several Honduran populations revealed a level of differentiation associated with a negligible rate of gene flow.     

Fixed Differences in the paralytic Gene Define Two Lineages within the Lutzomyia longipalpis Complex Producing Different Types of Courtship Songs

The sand fly Lutzomyia longipalpis (Diptera: Psychodidae: Phlebotominae), the most important vector of American visceral leishmaniasis, is widely distributed in Latin America. There is currently a consensus that it represents a species complex, however, the number and distribution of the different siblings is still uncertain. Previous analyses have indicated that Brazilian populations of this vector can be divided into two main groups according to the type of courtship song (Burst vs. Pulse) males produce during copulation. Nevertheless, no diagnostic differences have been observed between these two groups with most molecular markers used to date. We analyzed the molecular divergence in a fragment of the paralytic (para) gene, a locus involved in the control of courtship songs in Drosophila, among a number of Lu. longipalpis populations from Brazil producing Burst and Pulse-type songs. Our results revealed a very high level of divergence and fixed differences between populations producing the two types of songs. We also compared Lu. longipalpis with a very closely related species, Lutzomyia cruzi, which produces Burst-type songs. The results indicated a higher number of fixed differences between Lu. cruzi and the Pulse-type populations of Lu. longipalpis than with those producing Burst-type songs. The data confirmed our previous assumptions that the presence of different sibling species of the Lu. longipalpis complex in Brazil can be divided into two main groups, one representing a single species and a second more heterogeneous group that probably represents a number of incipient species. We hypothesize that para might be one of the genes directly involved in the control of the courtship song differences between these two groups or that it is linked to other loci associated with reproductive isolation of the Brazilian species.     

Copulatory courtship song in Lutzomyia migonei (Diptera: psychodidae)

Lutzomyia migonei is a vector of leishmaniasis with a wide distribution in South America, which could favour population differentiation and speciation. Cryptic species of the Lutzomyia longipalpis complex, the widely distributed sand fly vector of visceral leishmaniasis in Latin America, have previously been shown to display distinct copulation songs. We found that Lu. migonei males also produce a song during copulation. This "lovesong" presents short trains (6-8 pulses) with an inter-pulse interval around 26 ms and is potentially involved in cryptic female choice and insemination success.     

Analysis of the sex pheromone extract of individual male Lutzomyia longipalpis sandflies from six regions in Brazil

Although the phlebotomine sandfly Lutzomyia longipalpis (Lutz & Neiva, 1912) (Diptera: Psychodidae) is generally accepted to be a species complex, it is unclear how many members there are, how they are related and which are the main vectors of leishmaniasis. The vectorial capacity of each sibling species is likely to differ, thus a means of identifying the most important vector species is of critical importance to the epidemiology and control of this debilitating disease in South and Central America. In Brazil four chemotypes have been distinguished by sex pheromone analysis. In this study the sex pheromone extracts of L. longipalpis from six regions of Brazil were analysed in detail. Samples included the sympatric 1-spot, 2-spot and intermediate spot morphotypes from Sobral, Ceará State. The results strongly suggest that members of the complex that produce different sex pheromones are reproductively isolated, thus strengthening the argument that the different chemotypes represent true sibling species. The study also found significant differences in morphology and the amounts of sex pheromone produced by members of each chemotype from different parts of Brazil, which suggests population substructuring that has not previously been recognized. Evidence of a fifth chemotype in Brazil is also presented.     

Courtship song genes and speciation in sand flies

Lutzomyia longipalpis (Lutz & Neiva, 1912) (Diptera: Psychodidae: Phlebotominae) is a vector of visceral leishmaniasis in the Americas and it might represent a complex of sibling species. Reproductive isolation between closely related species often involves differences in courtship behaviour. cacophony (cac) and period (per) are two Drosophila genes that control features of the "lovesong" males produce during courtship that has been implicated in the sexual isolation between closely related species. We are using gene fragments from L. longipalpis' homologues of these two genes to study the speciation process in this putative species complex.     

The Lutzomyia longipalpis species complex: does population sub-structure matter to Leishmania transmission?

Leishmania chagasi causes visceral leishmaniasis and, to a lesser extent, atypical cutaneous leishmaniasis in Central and South America. Its main sand fly vector, Lutzomyia longipalpis s.l. (Diptera: Psychodidae) displays a complex population structure that might contribute to the observed clinical pleomorphism and to recent major urban epidemics. This article summarises our understanding on reproductive barriers and hybridisation among this vector's sibling incipient species. Identifying genes important for sand fly ecological adaptability and sand fly-Leishmania genetic co-variation could be helpful for interrupting Leishmania transmission.     

Detection of Leishmania infantum in naturally infected Lutzomyia longipalpis (Diptera: Psychodidae: Phlebotominae) and Canis familiaris in Misiones, Argentina: the first report of a PCR-RFLP and sequencing-based confirmation assay

In this study, a genotypification of Leishmania was performed using polimerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and sequencing techniques to identify species of Leishmania parasites in phlebotomine sand flies and dogs naturally infected. Between January-February of 2009, CDC light traps were used to collect insect samples from 13 capture sites in the municipality of Posadas, which is located in the province of Misiones of Argentina. Sand flies identified as Lutzomyia longipalpis were grouped into 28 separate pools for molecular biological analysis. Canine samples were taken from lymph node aspirates of two symptomatic stray animals that had been positively diagnosed with canine visceral leishmaniasis. One vector pool of 10 sand flies (1 out of the 28 pools tested) and both of the canine samples tested positively for Leishmania infantum by PCR and RFLP analysis. PCR products were confirmed by sequencing and showed a maximum identity with L. infantum. Given that infection was detected in one out of the 28 pools and that at least one infected insect was infected, it was possible to infer an infection rate at least of 0.47% for Lu. longipalpis among the analyzed samples. These results contribute to incriminate Lu. longipalpis as the vector of L. infantum in the municipality of Posadas, where cases of the disease in humans and dogs have been reported since 2005.     

Host preferences of the phlebotomine sandfly Lutzomyia longipalpis in Amazonian Brazil

Experiments were undertaken to determine the relative attractiveness of humans, dogs and chickens to Lutzomyia longipalpis, the principal vector of Leishmania chagasi causing American visceral leishmaniasis. Field experiments in two villages on Marajó Island, Pará State, Brazil, showed that one boy attracted significantly more flies than one dog or chicken, and slightly fewer flies than a group of six chickens. Experiments with laboratory-bred female flies showed that a significantly greater number of flies engorged on a single human than on either a single dog or chicken, and man-biting catches demonstrated the willingness of flies to bite in the field. It appears that Lu.longipalpis has catholic feeding habits, the attractiveness of different hosts being largely a function of their relative sizes. These results are discussed with reference to the epidemiology of visceral leishmaniasis in Brazil.     

Lutzomyia longipalpis and the eco-epidemiology of American visceral leishmaniasis, with particular reference to Brazil: a review

An historical review is given of American visceral leishmaniasis (AVL), with particular reference to the eco-epidemiology of the disease in Brazil. Following the first records of AVL in this country, in 1934, the sandfly Lutzomyia longipalpis (Lutz and Neiva, 1912) was incriminated as the principal vector. It is now generally accepted, however, that there exist a number of cryptic species under the name of Lu. longipalpis s.l. and that variations in the quantity of the vasodilatory peptide maxadilan in the saliva of flies from different populations of Lu. longipalpis s.l., may account for the variable clinical manifestations of AVL seen in different geographic regions. Distribution of AVL has been shown to extend throughout most of South and Central America, with the domestic dog serving as the principal reservoir of infection for man. However, while one hypothesis suggests that the causative parasite is Leishmania infantum, imported from Europe with the Portuguese and Spanish colonists, the demonstration of a high rate of benign, inapparent infection in foxes in Amazonian Brazil raised an opposing suggestion that the parasite is indigenous to the Americas. Recent reports of similar infections in native marsupials, and possibly rodents, tend to support this view, particularly as Lu. longipalpis is primordially a silvatic sandfly. Although effective control measures in foci of the disease will diminish the number of canine and human infections, the presence of such an enzootic in a variety of native animals will render the total eradication of AVL unlikely.     

The re-emergence of American visceral leishmaniasis in an old focus in Venezuela. II. Vectors and parasites.

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 L. 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.     

Activity of Lutzomyia pseudolongipalpis and L. longipalpis s.l. (Diptera: Psychodidae) in Venezuela

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.     

A comparison of molecular markers to detect Lutzomyia longipalpis naturally infected with Leishmania (Leishmania) infantum

The aim of the present study was to detect natural infection by Leishmania (Leishmania) infantum in Lutzomyia longipalpis captured in Barcarena, state of Pará, Brazil, through the use of three primer sets. With this approach, it is unnecessary to previously dissect the sandfly specimens. DNA of 280 Lu. longipalpis female specimens were extracted from the whole insects. PCR primers for kinetoplast minicircle DNA (kDNA), the mini-exon gene and the small subunit ribosomal RNA (SSU-rRNA) gene of Leishmania were used, generating fragments of 400 bp, 780 bp and 603 bp, respectively. Infection by the parasite was found with the kDNA primer in 8.6% of the cases, with the mini-exon gene primer in 7.1% of the cases and with the SSU-rRNA gene primer in 5.3% of the cases. These data show the importance of polymerase chain reaction as a tool for investigating the molecular epidemiology of visceral leishmaniasis by estimating the risk of disease transmission in endemic areas, with the kDNA primer representing the most reliable marker for the parasite.     

First record of Lutzomyia evansi (Nuñez-Tovar 1924) in Mexico (Diptera: Psychodidae, Phlebotominae)

The phlebotomine sand fly Lutzomyia evansi is recorded in Mexico for the first time. This species is a suspected vector of Leishmania infantum in other parts of its geographical range and was captured in a focus of American visceral leishmaniasis where the principal vector, Lu. longipalpis sensu lato, was also found. The relative public health importance of the two species in the study area (Chiapas state, Southern Mexico) is discussed.     

Analysis of the activity patterns of two sympatric sandfly siblings of the Lutzomyia longipalpis species complex from Brazil

Abstract.  Lutzomyia longipalpis s.l. (Lutz & Neiva) (Diptera: Psychodidae) is the main vector of visceral leishmaniasis in Latin America. Differences in copulation songs, pheromones and molecular markers show that L.  longipalpis is a species complex in Brazil. The patterns of activity of insect vectors are important in disease transmission. In addition, differences in activity rhythms have a potential role as a temporal reproductive isolation mechanism in closely related species. We compared the activity patterns of males and females of two sympatric species of the Longipalpis complex from Sobral (Ceará State, Brazil) in controlled laboratory conditions. We observed small but significant differences between the two species in the activity phase in both males and females.     

Wing geometry as a tool for studying the Lutzomyia longipalpis (Diptera: Psychodidae) complex

Toro Toro (T) and Yungas (Y) have been described as genetically well differentiated populations of the Lutzomyia longipalpis (Lutz & Neiva, 1912) complex in Bolivia. Here we use geometric morphometrics to compare samples from these populations and new populations (Bolivia and Nicaragua), representing distant geographical origins, qualitative morphological variation ("one-spot" or "two-spots" phenotypes), ecologically distinct traits (peridomestic and silvatic populations), and possibly different epidemiological roles (transmitting or nor transmitting Leishmania chagasi). The Nicaragua (N) (Somotillo) sample was "one-spot" phenotype and a possible peridomestic vector. The Bolivian sample of the Y was also "one-spot" phenotype and a demonstrated peridomestic vector of visceral leishmaniasis (VL). The three remaining samples were silvatic, "two-spots" phenotypes. Two of them (Uyuni and T) were collected in the highlands of Bolivian where VL never has been reported. The last one (Robore, R) came from the lowlands of Bolivia, where human cases of VL are sporadically reported. The decomposition of metric variation into size and shape by geometric morphometric techniques suggests the existence of two groups (N/Y/R, and U/T). Several arguments indicate that such subdivision of Lu. longipalpis could correspond to different evolutionary units.     

Leishmania infection in humans, dogs and sandflies in a visceral leishmaniasis endemic area in Maranhão, Brazil

Leishmania infection in humans, dogs and sandflies was examined in the endemic visceral leishmaniasis (VL) municipality of Raposa, state of Maranh?o, Brazil. In this study, we examined Leishmania chagasi infection in the blood serum of both humans and Canis familiaris and the natural Leishmania sp. infection rate in the sandfly vector, Lutzomyia longipalpis. Enzyme-linked immunosorbent assay, indirect immunofluorescence reaction and polymerase chain reaction were performed to detect Leishmania infections in humans, dogs and sandflies, respectively. Overall, 186 out of 986 studied human beings were infected with L. chagasi parasites, representing an infection prevalence of 18.9%. An even higher infection rate was detected in dogs, where 66 (47.8%) out of 138 were infected. Among all Lu. longipalpis captured (n = 1,881), only 26.7% were females. The Leishmania infection frequency for the vector Lu. longipalpis was 1.56%. Remarkably, all infected sandflies were found in the peridomiciliary area. Furthermore, a high incidence of asymptomatic forms of VL in the human and canine populations was observed. The results of this study suggest autochthonous transmission of L. chagasi in this endemic area for visceral leishmaniasis because infection by Leishmania sp. was identified in all important elements of the transmission chain.     

Lutzomyia longipalpis in Uruguay: the first report and the potential of visceral leishmaniasis transmission

Phlebotomine captures were performed in February 2010 in Salto (Salto department) and Bella Unión-Cuarein (Artigas department), Uruguay. Bella Unión is located across the Paraná River from Monte Caseros, Argentina, where a focus of canine visceral leishmaniasis (VL) was reported in 2009. No VL cases have ever been recorded in Uruguay and the last reported capture of Phlebotominae was in 1932 (Lutzomyia cortelezzii and Lutzomyia gaminarai). Light traps were placed in peridomestic environments, and Lutzomyia longipalpis, the main vector of visceral leishmaniasis, was found in Salto and Bella Unión. This is a first report of an area of potential VL transmission in Uruguay. Active and coordinated surveillance is required immediately the Uruguay-Argentina-Brazil border area.     

Diversity, distribution and abundance of sandflies (Diptera: Psychodidae) in Parana State, Southern Brazil

Due to the spread of Visceral leishmaniasis in Brazilian territory, this research was undertaken with the objective to identify the sandfly fauna and aspects of the species behavior in forest and anthropic environments in Paraná State, Brazil. The sandfly captures were sporadically carried out in 37 municipalities of the Paraná state, during the period from March 2004 to November 2005. Each municipality was once visited, when Falc?o traps were installed during three consecutive nights in forested fragments and anthropic environments; captures with Shannon traps installed in forests and edge of forests, inspection of walls and electric aspiration in domiciles and forested areas were sporadically undertaken. The data analysis was based on estimates of frequency and abundance of the species, by five native landscapes. A total of 38,662 specimens belonging to 23 species were captured. Nyssomyia neivai (Pinto) (75.6%), Ny. whitmani (Antunes & Coutinho) (10.1%), Migonemyia migonei (Fran?a) (7.8%), Expapillata firmatoi (Barreto et al.) (2.1%) and Pintomyia fischeri (Pinto) (1.6%) together constituted 97.2% of the phlebotomine collected. High frequencies of sand flies were found in forests, henhouses, pig-pens and domiciles. The three most frequent species have been implicated in transmission of tegumentary leishmaniasis in Paraná and in the Brazilian Southeastern and Southern Regions. Lutzomyia longipalpis (Lutz & Neiva), the visceral leishmaniasis vector, was not found, however Lutzomyia gaminariai (Cordero et al.), female of which is similar to that of Lu. longipalpis was captured, raising the need to investigate its behavior, including as regard to the vectorial competence.