Natural infection of phlebotomines (Diptera: Psychodidae) in a visceral-leishmaniasis focus in Mato Grosso do Sul, Brazil

Molecular identification of phlebotomine sand flies and the harbored Leishmania spp. in Sokoto State, Nigeria

Introduction

Female sand flies are hematophagous, feeding on animals and in the process serve as vectors for Leishmania, the parasites that cause leishmaniasis in humans. Leishmaniasis are a group of parasitic neglected tropical diseases in 98 countries including Nigeria and kills ~60,000 people/year. In Nigeria, Sokoto State is endemic to leishmaniasis but there is a knowledge gap on the identity of the prevalent sand flies and the Leishmania species they transmit. Hence, this cross-sectional study was designed to take inventory of the species of sand flies in Sokoto using genetic methods.

Methods

1,260 (310 females) sand flies were collected from three Local Government Areas (L.G.A) of Sokoto State- Wamakko, Sokoto South and Kware. Genomic DNA was extracted from each fly and DNA amplification by polymerase chain reaction (PCR) was carried out on the DNA samples using primers targeting the arthropods mitochondrial cytochrome oxidase subunit 1 (mt-coI) gene, and nested PCR with primers targeting the gene for Leishmania internal transcribed spacer-1 (its-1) of ribosomal RNA its-1rRNA. The PCR products were sequenced.

Results

Gene sequence analysis revealed five species of sand flies belonging to the old-world genera namely Phlebotomus and Sergentomyia. The identified species were P. papatasi (6.45%), S. adleri (6.45%), S. affinis (9.7%), S. distincta (9.7%), S. schwetzi (67.7%). Within the sampling period, sand flies were most abundant in the rainy months of August (104/33.5%) and September (116/37.4%) with all the five identified species occurring. Sequence analysis of its-1 gene identified Leishmania infantum in two sand flies (2/310)- P. papatasi (from Sokoto South) and S. affinis (from Wamakko). BLAST search in NCBI and phylogenetic analysis revealed that the sand fly species are related to the species reported in different parts of Africa, while the L. infantum is identical to strain reported in Brazil (KY379083.1).

Discussion

Phlebotomus papatasi and four species belonging to the genus Sergentomyia are the most prevalent sand flies in Sokoto State, Nigeria and they harbor L. infantum solely. The results shed light on why visceral leishmaniasis is the most predominant form of the disease. Therefore, we recommend that adequate care for dogs must be instituted as dogs are the major animal reservoir for L. infantum.

Phlebotominae (Diptera: Psychodidae) and Biomes in the State of Mato Grosso do Sul, Brazil

The state of Mato Grosso do Sul, Brazil is an important region of South America regarding leishmaniasis, with the great diversity of sandflies reported since 1938 and wide biodiversity represented by its biomes (Atlantic Forest, Cerrado, and Pantanal). A checklist of sandflies is presented here for the state and respective biomes. The data base was compiled from primary and secondary data. The primary data collection involved automatic light traps at Miranda-Abobral Pantanal subregion and in subregion Baixa Nhecolância of Pantanal. The secondary data were obtained from entomology scientific collections and a literature review of articles from 1938 to 2019, including entomological museum collections. A total of 71 species were reported, belonging to 14 genera and 13 subgenera, in 61 municipalities of the state, including the type locality of 9 species, and the first report of Lutzomyia cruzi (Mangabeira 1938), vector of Leishmania infantum (Nicolle 1937), in the Pantanal region of Miranda-Abobral. Other vector species, Bichromomyia flaviscutellata (Mangabeira 1942), Lutzomyia longipalpis (Lutz & Neiva 1912), Nyssomyia antunesi (Coutinho 1939), Nyssomyia intermedia (Lutz & Neiva 1912), Nyssomyia neivai (Pinto 1926), and Nyssomyia whitmani (Antunes & Coutinho 1939), are reported in the entire area of the state. Maps containing the distribution of sandflies on Mato Grosso do Sul biomes were produced. The eclecticism of the species in relation to their ecotypes was observed, with several species using the three biome types as habitats and breeding sites.

Leishmania spp. Infection Rate and Feeding Patterns of Sand Flies (Diptera: Psychodidae) from a Hyperendemic Cutaneous Leishmaniasis Community in Panamá

American cutaneous leishmaniasis (ACL) is a common and important vector-borne parasitic zoonosis in Panamá. Here, we study Leishmania spp. infection rates and blood-feeding patterns among common sand flies in Trinidad de Las Minas, a rural community with hyperendemic ACL transmission, and where a deltamethrin fogging trial was performed. Sand flies were collected from April 2010 to June 2011 with light traps installed inside and in the peridomicile of 24 houses. We restricted our analysis to the most abundant species at the study site: Lutzomyia trapidoi, Lutzomyia gomezi, Lutzomyia panamensis, Lutzomyia triramula, and Lutzomyia dysponeta. We detected Leishmania spp. infection in sand flies by polymerase chain reaction (PCR) amplification of the internal transcribed spacer region 1 (ITS-1) in pooled females (1-10 females per pool). Host species of engorged sand flies were identified using a cytochrome b PCR. From 455 sand fly pools analyzed, 255 pools were positive for Leishmania spp., with an estimated infection rate (confidence interval) of 0.096 [0.080-0.115] before the deltamethrin fogging which slightly, but not significantly (P > 0.05), increased to 0.116 [0.098-0.136] after the deltamethrin fogging. Blood meal analysis suggested that pigs, goats, and birds were the most common sand fly blood sources, followed by humans and domestic dogs. DNA sequencing from a subsample of ITS-1 positive pools suggests that Leishmania panamensis, Leishmania naiffi, and other Leishmania spp. were the parasite species infecting the most common vectors at the study site. Our data confirm an association between sand fly species, humans, domestic dogs, and pigs and Leishmania spp. parasites in rural Panamá.

Ecology and Molecular Detection of Leishmania infantum Nicolle, 1908 (Kinetoplastida: Trypanosomatida) in Wild-Caught Sand Flies (Psychodidae: Phlebotominae) Collected in Porto Alegre, Rio Grande do Sul: A New Focus of Visceral Leishmaniasis in Brazil

Phlebotomine sand flies are hematophagous insect vectors of the protozoan parasites of the genus Leishmania Ross, 1903 (Kinetoplastida: Trypanosomatida) that infect mammals, including humans, causing leishmaniasis. In Porto Alegre, Brazil, three autochthonous cases of human visceral leishmaniasis were reported in 2016 through 2017. We analyzed for the presence of Leishmania DNA in sand flies collected at the neighborhood of Agronomia, Porto Alegre, Brazil. Phlebotomine sand flies were collected at three sites from October 2014 to September 2015. Female sand flies were pooled in numbers from 1 to 20 depending upon species, locality, and date; all were screened for Leishmania infection by the amplification of the ITS1 region. In total 518 phlebotomine sand flies were collected: Psathyromyia lanei (Barretto and Coutinho, 1941) (Diptera: Psychodidae) (30.5%), Brumptomyia sp. (França and Parrrot, 1921) (Diptera: Psychodidae) (25.7%), Migonemyia migonei (Franca, 1920) (Diptera: Psychodidae) (21.4%), Pintomyia fischeri (Pinto, 1926) (Diptera: Psychodidae) (21.4%), and Nyssomyia neivai (Pinto, 1926) (Diptera: Psychodidae) (1.0%). Most sand flies were collected during the hot and rainy season from October 2014 to April 2015. Of the 113 pools analyzed, five pools of Pi. fischeri were PCR-positive with the amplicons possessing sequences similar (>95%) to that of Leishmania infantum Nicolle, 1908 (Kinetoplastida: Trypanosomatida). These results represent the first molecular detection of Le. infantum in Pi. fischeri. It is possible that Pi. fischeri is involved in the transmission cycle of Le. infantum in the studied area; however, further studies are needed to establish the true role of Pi. fischeri in the visceral leismaniasis cycle.

High molecular prevalence of Leishmania in phlebotomine sand flies fed on chicken blood in Brazil

Leishmaniases are endemic in Brazil, where Leishmania infantum has been detected in humans, dogs, cats, and phlebotomine vectors. Monitoring synanthropic vector populations is critical for leishmaniasis control-surveillance in such transmission-prone areas. Here, a suite of molecular approaches were used to assess Leishmania infection prevalence and to identify blood-meal sources in a large sample of sand flies collected in anthropic environments of a Leishmania-transmission area in Mato Grosso do Sul State (Rio Verde de Mato Grosso municipality), Central-West Brazil. We sampled sand flies monthly (January-June 2014 and 2016) in one peri-domestic site within each of six neighborhoods with recent records of human visceral and/or tegumentary leishmaniasis. kDNA-qPCR plus rDNA ITS-sequencing were used to detect and identify Leishmania in pooled female sand flies. Individual engorged females (n = 58) were used for blood-meal analyses through High-Resolution Melting (HRM) targeting the mtDNA cytb gene. Overall, 90.5% of 420 CDC trap-nights yielded vectors, for a total catch of 24,989 sand flies. We sub-sampled and identified 3088 sand flies of 12 species, including 2775 Lutzomyia longipalpis (the most abundant species at all sampling sites) and 297 Nyssomyia whitmani. Female sand flies (n = 1261) were grouped in 159 pools, of which 92 Lu. longipalpis (minimum infection rate [MIR] 8%) and 7 Ny. whitmani pools (MIR 7%) were Leishmania kDNA-positive. Most positive Lu. longipalpis were collected in the 2016 rainy season. Sequencing confirmed L. infantum in Lu. longipalpis samples. HRM analyses identified chicken DNA in 57 sand flies (98.3%), 37 of which were Leishmania DNA-positive (64.9%); human blood was found in just one (Leishmania-negative) female. Our data show ongoing risk of L. infantum transmission to humans in the study area, where Leishmania-infected sandfly vectors are common and heavily rely on chicken blood in the peri-domestic environment.

Aspects of the ecology of phlebotomine sand flies (Diptera: Psychodidae) in the Private Natural Heritage Reserve Sanctuary Caraça

Leishmaniases are a set of parasitic diseases of zoonotic origin that are transmitted by sandfly vectors in wild, rural and urban environments. Their distribution is dependent not only the distribution of vectors, but also on the distribution of mammalian reservoirs. Only by understanding the transmission cycle of these diseases, such as knowing the participating vectors and reservoirs, can one can understand the epidemiology and ecological relationships of leishmaniases. Ecotourism has become an important area of economic growth in Brazil. One of the most visited tourist attractions in the state of Minas Gerais, the Reserva Particular do Patrimônio Natural Santuário do Caraça (RPPNSC) is located in the Quadrilátero Ferrífero. The aim of this study was to contribute to the control of leishmaniasis among tourists of the RPPNPC by surveying its sand fly fauna and testing for the presence of Leishmania DNA in females. Twenty-five CDC light traps were exposed on 7 trails of the RPPNPC where samples were collected bimonthly for a year, starting in June 2013. A total of 376 specimens of 18 species and 10 genera of sandflies were captured. The predominant species were Psychodopygus lloydi (72.34%) and Pintomyia monticola (5.59%). HaeIII restriction enzyme detected and characterized Leishmania braziliensis DNA in 2 of the samples for an infection rate of 0.7% (2/266). Recent studies found specimens of Ps. lloyd infected with Leishmania braziliensis elsewhere in Minas Gerais, which may be an indication that this species is involved in the transmission of Leishmania in this state.

Molecular Detection of Leishmania DNA in Wild-Caught Phlebotomine Sand Flies (Diptera: Psychodidae) From a Cave in the State of Minas Gerais, Brazil

Leishmania spp. are distributed throughout the world, and different species are associated with varying degrees of disease severity. In Brazil, Leishmania transmission involves several species of phlebotomine sand flies that are closely associated with different parasites and reservoirs, and thereby giving rise to different transmission cycles. Infection occurs during the bloodmeals of sand flies obtained from a variety of wild and domestic animals, and sometimes from humans. The present study focused on detection of Leishmania DNA in phlebotomine sand flies from a cave in the state of Minas Gerais. Detection of Leishmania in female sand flies was performed with ITS1 PCR-RFLP (internal transcribed spacer 1) using HaeIII enzyme and genetic sequencing for SSUrRNA target. The survey of Leishmania DNA was carried out on 232 pools and the parasite DNA was detected in four: one pool of Lutzomyia cavernicola (Costa Lima, 1932), infected with Le. infantum (ITS1 PCR-RFLP), two pools of Evandromyia sallesi (Galvão & Coutinho, 1939), both infected with Leishmania braziliensis complex (SSUrRNA genetic sequencing analysis), and one pool of Sciopemyia sordellii (Shannon & Del Ponte, 1927), infected with subgenus Leishmania (SSUrRNA genetic sequencing analysis). The present study identified the species for Leishmania DNA detected in four pools of sand flies, all of which were captured inside the cave. These results represent the first molecular detection of Lu cavernicola with Le infantum DNA, Sc sordellii with subgenus Leishmania DNA, and Ev sallesi with Leishmania braziliensis complex DNA. The infection rate in females captured for this study was 0.17%.

Nycthemeral Rhythm of Phlebotominae (Diptera: Psychodidae) in a Craggy Region, Transitioning Between the Wetland and the Plateau, Brazil

Recording the nycthemeral rhythm of sand flies allows the evaluation of the daily activity in different ecotypes, the period of greatest activity, and their degree of anthropophily. We investigated the fauna and the rhythm of sand fly activity in an ecotourism region in Mato Grosso do Sul (MS) state, Brazil. Sand flies were captured monthly, using a Shannon trap for 24 h periods between July 2012 and June 2014. We collected 1,815 sand flies, in which Lutzomyia whitmani (=Nyssomyia whitmani, sensu Galati) and Lutzomyia longipalpis were the most abundant species during the dry season, with activity from 5 p.m.-7 a.m. and 6 p.m.-5 a.m., respectively. Both species require particular attention as vectors of Leishmania (Viannia) braziliensis and Leishmania (Leishmania) infantum in several regions of Brazil, including MS. However, Lutzomyia dispar was more anthropophilic, and was most active between January and March, from 5 p.m. to 5 a.m. Lutzomyia misionensis (=Pintomyia misionensis, sensu Galati) was present throughout both years, active from 4 p.m. to 5 a.m. Other species were active from 5 p.m. to 6 a.m. Due to intense tourism in the months that coincide with a high number of vectors for leishmaniases in Piraputanga, it is essential to determine vector-monitoring strategies in the area by investigating sand fly rhythm while not neglecting other periods of the year when the insects are present.

Frequency and diversity of phlebotomine sand flies (Diptera: Psychodidae) in Sinop, State of Mato Grosso, Brazil

INTRODUCTION:

Understanding the diversity of sand flies is important for the epidemiology and control of leishmaniasis. This study aimed to understand the frequency, diversity, and seasonality of medically important sand flies in the municipality of Sinop, State of Mato Grosso, Brazil.

METHODS:

The study was conducted in an urban area, including four ecotypes with different levels of urbanization. The sand flies were collected using light traps for three nights per month, from May 2014 to April 2015.

RESULTS:

A total of 62,745 sand flies was collected, 52.34% of which were female. The frequency and diversity of sand flies was the highest in areas of permanent preservation (APPs) (96.85%), and was lower in more urbanized areas. Lutzomyia dasypodogeton was the most frequent species in the APPs. Lutzomyia antunesi was the most frequent in neighborhoods with forest fragments and neighborhoods around APPs, and L. aragaoi was the most frequent in completely urbanized neighborhoods. A higher frequency and diversity of sand flies was observed in the rainy season (87.92%) than in the dry season (12.08%). Eight medically important species were captured, and Lutzomyia antunesi, which is associated with American cutaneous leishmaniasis and visceral leishmaniasis, was observed in all ecotypes throughout the year.

CONCLUSIONS:

We observed a high frequency and diversity of sand flies in all urban areas, and some species collected were major vectors of leishmaniasis. These results support the need for further studies of the natural rates of infection of these insects and the circulation of the disease in hosts and vectors.

Molecular detection of Leishmania in phlebotomine sand flies (Diptera: Psychodidae) from a cutaneous leishmaniasis focus atXakriabá Indigenous Reserve, Brazil

Autochthonous cases of American cutaneous leishmaniasis (ACL) have been reported since 2001 in the Xakriabá Indigenous Reserve located in the municipality of São João das Missões in northern Minas Gerais state, Brazil. In order to study the presence of Leishmania DNA in phlebotomine sand flies, six entomological collections were carried out from July 2008 through July 2009, using 40 light traps placed in peridomicile areas of 20 randomly selected houses. From October 2011 through August 2012, another six collections were carried out with 20 light traps distributed among four trails (five traps per trail) selected for a previous study of wild and synanthropic hosts of Leishmania. A total of 4,760 phlebotomine specimens were collected belonging to ten genera and twenty-three species. Single female specimens or pools with up to ten specimens of the same locality, species and date, for Leishmania detection by molecular methods. Species identification of parasites was performed with ITS1 PCR-RFLP using HaeIII enzyme and genetic sequencing for SSU rRNA target. The presence of Leishmania DNA was detected in eleven samples from peridomicile areas: Lu. longipalpis (two), Nyssomyia intermedia (four), Lu. renei (two), Lu. ischnacantha, Micropygomyia goiana and Evandromyia lenti (one pool of each specie). The presence of Leishmania DNA was detected in twelve samples from among the trails: Martinsmyia minasensis (six), Ny. intermedia (three), Mi. peresi (two) and Ev. lenti (one). The presence of Leishmania infantum DNA in Lu. longipalpis and Leishmania braziliensis DNA in Ny. intermediasupport the epidemiological importance of these species of sand flies in the cycle of visceral and cutaneous leishmaniasis, respectively. The results also found other species associated with Leishmania DNA, such as Mt. minasensis and Ev. lenti, which may participate in a wild and/or synanthropic cycle of Leishmania transmission in the studied area.

Phlebotomine fauna, natural infection rate and feeding habits of Lutzomyia cruzi in Jaciara, state of Mato Grosso, Brazil

Visceral leishmaniasis (VL) in Brazil is transmitted by the phlebotomine Lutzomyia longipalpis and in some midwestern regions by Lutzomyia cruzi. Studies of the phlebotomine fauna, feeding habits and natural infection rate by Leishmania contribute to increased understanding of the epidemiological chain of leishmaniases and their vectorial capacity. Collections were performed in Jaciara, state of Mato Grosso from 2010-2013, during which time 2,011 phlebotomines (23 species) were captured (68.70% Lu. cruzi and 20.52% Lutzomyia whitmani). Lu. cruzi females were identified by observing the shapes of the cibarium (a portion of the mouthpart) and spermatheca, from which samples were obtained for polymerase chain reaction to determine the rates of natural infection. Engorged phlebotomines were assessed to identify the blood-meal host by ELISA. A moderate correlation was discovered between the number of Lu. cruzi and the temperature and the minimum rate of infection was 6.10%. Twenty-two females were reactive to the antisera of bird (28%), dog (3.30%) and skunk (1.60%). We conclude that Lu. cruzi and Lu. whitmani have adapted to the urban environment in this region and that Lu. cruzi is the most likely vector of VL in Jaciara. Moreover, maintenance of Leishmania in the environment is likely aided by the presence of birds and domestic and synanthropic animals.

Epidemiological survey of Lutzomyia longipalpis infected by Leishmania infantum in an endemic area of Brazil

The objective of this study was to perform an epidemiological survey to determine the areas at risk of visceral leishmaniasis through the detection and quantification of natural infection by Leishmania infantum in Lutzomyia longipalpis. The sandflies were captured between February 2009 and January 2010, at 21 sites in four regions of the Fortaleza municipality. Samples were screened for the presence of Leishmania DNA by Real Time PCR (qPCR), amplification of kDNA minicircle sequence. Out of the 123 pools of analyzed sandflies, 45 were positive for L.infantum, and the minimum infection rate was 3.7%. In the north, south, east and west regions, the pool screen assay predicted sand-fly infection prevalence of 3.4%, 4.7%, 4.9% and 8.4%, respectively. The parasite load ranged from 2.45 ± 0.96 to 2,820,246 ± 106,072. No statistical differences were found with respect to the frequency of sand-fly infection between the regions (P=0.3014), seasons (P = 0.3906) or trap locations (P = 0.8486). Statistical differences were found with respect to the frequency of sand-fly infection between the two seasons only in the west region (P=0.0152). The qPCR was able to detect and quantify L. infantum in L. longipalpis, therefore succeeding in identifying the areas of greatest risk of VL transmission.

Distribution of phlebotomine fauna (Diptera: Psychodidae) across an urban-rural gradient in an area of endemic visceral leishmaniasis in northern Brazil

The number of visceral leishmaniasis (VL) cases has increased over the past 10 years in Brazil, especially in the North and Northeast regions of the country. The aim of this study was to evaluate the urbanisation of VL vectors in Barcarena, Pará, an area in northern Brazil where VL is endemic. Sandflies were captured using Centers for Disease Control (CDC) light traps along an urban-rural gradient. The CDC traps were installed inside hen houses at a height of 150 cm. A total of 5,089 sandflies were collected and 11 species were identified. The predominant species was Lutzomyia longipalpis (rate of 95.15%), which suggests its participation in the transmission of VL. A total of 1,451 Lu. longipalpis females were dissected and no Leishmania infections were detected. Most of the sandflies were captured at the border of a forest (88.25%) and no flies were captured in the urban area, which suggests that transmission is still restricted to rural sites. However, the fact that a specimen was collected in an intermediate area indicates that urbanisation is a real possibility and that vector monitoring is important.

The genetic structure of Leishmania infantum populations in Brazil and its possible association with the transmission cycle of visceral leishmaniasis

Leishmania infantum is the etiologic agent of visceral leishmaniasis (VL) in the Americas, Mediterranean basin and West and Central Asia. Although the geographic structure of L. infantum populations from the Old World have been described, few studies have addressed the population structure of this parasite in the Neotropical region. We employed 14 microsatellites to analyze the population structure of the L. infantum strains isolated from humans and dogs from most of the Brazilian states endemic for VL and from Paraguay. The results indicate a low genetic diversity, high inbreeding estimates and a depletion of heterozygotes, which together indicate a predominantly clonal breeding system, but signs of sexual events are also present. Three populations were identified from the clustering analysis, and they were well supported by F statistics inferences and partially corroborated by distance-based. POP1 (111 strains) was observed in all but one endemic area. POP2 (31 strains) is also well-dispersed, but it was the predominant population in Mato Grosso (MT). POP3 (31 strains) was less dispersed, and it was observed primarily in Mato Grosso do Sul (MS). Strains originated from an outbreak of canine VL in Southern Brazil were grouped in POP1 with those from Paraguay, which corroborates the hypothesis of dispersal from Northeastern Argentina and Paraguay. The distribution of VL in MS seems to follow the west-east construction of the Bolivia-Brazil pipeline from Corumbá municipality. This may have resulted in a strong association of POP3 and Lutzomyia cruzi, which is the main VL vector in Corumbá, and a dispersion of this population in this region that was shaped by human interference. This vector also occurs in MT and may influence the structure of POP2. This paper presents significant advances in the understanding of the population structure of L. infantum in Brazil and its association with eco-epidemiological aspects of VL.

Infecção natural de Lutzomyia (Lutzomyia) longipalpis (Diptera: Psychodidae) por Leishmania infantum chagasi em flebotomíneos capturados no município de Janaúba, Estado de Minas Gerais, Brasil

INTRODUÇÃO: A leishmaniose visceral tem sido notificada em quase todos os estados do Brasil, e principalmente no norte de Minas Gerais, onde a doença é endêmica. Este estudo visou detectar a infecção natural de Lutzomyia longipalpis e identificar através da técnica de PCR/RFLP a espécie de Leishmania encontrada nos flebotomíneos do município de Janaúba. MÉTODOS: Utilizando-se armadilhas luminosas, foram capturadas 1.550 fêmeas de L. longipalpis, que agrupadas em pool de 10 exemplares foram submetidas à extração e amplificação de DNA, através das técnicas de PCR genérico e cacofonia. RESULTADOS: Dos 155 pools, seis apresentaram-se positivos para Leishmania sp., sendo a taxa de infecção do município de 3,9%. Através da PCR/RFLP determinou-se que o padrão de digestão das amostras positivas foi semelhante ao da cepa referência Leishmania chagasi (MHOM/BR/74/PP75). CONCLUSÕES: A detecção de infecção natural associada a estudos sobre a epidemiologia da LV sugere que L. longipalpis esteja envolvida na transmissão de L. infantum chagasi em Janaúba, principalmente nas áreas de intensa transmissão de LV.

Detection of natural infection in Lutzomyia cruzi and Lutzomyia forattinii (Diptera: Psychodidae: Phlebotominae) by Leishmania infantum chagasi in an endemic area of visceral leishmaniasis in Brazil using a PCR multiplex assay

In order to identify Lutzomyia spp. naturally infected by Leishmania parasites a PCR multiplex assay coupled to non-isotopic hybridization was used for the analysis of insect samples collected by CDC light traps in an endemic area of visceral leishmaniasis (VL) in the municipality of Corumbá, Mato Grosso do Sul State, Brazil in May/June 2006. Wild sand flies were identified and grouped into pools of 10 female specimens and 27 groups in total were collected. Positive results were obtained from Lutzomyia cruzi (2 out of 13 pools) and Lutzomyia forattinii (1 out of 14 pools). The positive pools were confirmed as being infected by Leishmania infantum chagasi after hybridizing the PCR products with a species-specific biotinylated probe derived from the kinetoplast minicircle conserved sequence. Given that we detected infection in 3 out of 27 groups and that there was at least 1 infected insect in each, it was possible to infer an infection rate of 1.5% for Lu. cruzi and 0.7% for Lu. forattinii in the analyzed samples. These results confirm the vectorial role of Lu. cruzi in transmitting L. infantum chagasi and suggest Lu. forattinii as a potential VL vector in the municipality of Corumbá, where notifications of the disease in humans and dogs have increased over the last two decades.

Detection of Leishmania DNA in phlebotomines captured in Campo Grande, Mato Grosso do Sul, Brazil

Over the past years, leishmaniases have become a public health issue in the Brazilian state of Mato Grosso do Sul, particularly in Campo Grande, the state capital. The purpose of this study was to detect the presence of Leishmania DNA in the population of phlebotomine sandflies using DNA amplification by PCR. Insect captures were carried out from 4 pm. to 7 am for 4 consecutive days each month from October 2005 to September 2006 in 16 neighborhoods located in 7 urban regions of Campo Grande. Traps were placed indoors and in the vicinity of households. As many as 971 males and 203 females were collected. One hundred and five naturally fed females were identified and grouped as 1- to 4-specimen pools. DNA extraction was carried out using whole insects. Lutzomyia longipalpis predominated, accounting for 99.15% of the phlebotomines captured. Also found was Nyssomyia whitmani, the vector of tegumentary leishmaniasis. Abundance was greatest in the vicinity of households (69.8% of the phlebotomines captured). As revealed by PCR, parasites were present in 1.9% of the Leishmania spp. specimens investigated and confirmed for visceral leishmaniasis.