First report of Lutzomyia (Nyssomyia) umbratilis Ward & Frahia, 1977 outside of Amazonian Region, in Recife, State of Pernambuco, Brazil (Diptera: Psychodidae: Phlebotominae)

Revisiting the cave-dwelling sand flies (Diptera, Psychodidae, Phlebotominae) from Brazil: Diversity and potential role in the transmission of Leishmania Ross, 1903 (Kinetoplastida: Trypanosomatidae)

Brazilian caves, one of the many tourist attractions of the country, may act as a shelter for insects, such as sand flies (Diptera: Psychodidae), natural hosts of various microorganisms including parasites of the genus Leishmania Ross, 1903. In the last decades, with the increasing global need for sustainable development, ecotourism has emerged as one of the major activities in Brazil. However, the constant monitoring in environmentally protected areas is not often carried out, endangering visitors and professionals, especially due to the occurrence of zoonoses. Several sand fly species have already been recorded in Brazilian caves, drawing attention to the possibility of Leishmania transmission at this ecotope. Indeed, this current systematic review summarizes the fauna of cave-dwelling sand flies in Brazil, focusing on their biological behaviour and the occurrence of potential vectors of Leishmania parasites.

Beyond taxonomy: species complexes in New World phlebotomine sand flies

A species complex (= species group, species series) is an assemblage of species, which are related morphologically and phylogenetically. Recent research has revealed several arthropod vector species that were believed to be a single nominal species actually representing a group of closely related species, which are sometimes morphologically indistinguishable at one or more developmental stages. In some instances, differences in terms of vector competence, capacity, or both have been recorded. It highlights the importance of detecting and studying species complexes to improve our understanding of pathogen transmission patterns, which may be vectored more or less efficiently by different species within the complex. Considering more than 540 species, about one-third of the phlebotomine sand flies in the New World present males and/or females morphologically indistinguishable to one or more species. Remarkably, several of these species may act in transmission of pathogenic agents. In this article, we review recent research on species complexes in phlebotomine sand flies from the Americas. Possible practical implications of recently acquired knowledge and future research needs are also discussed.

Multiple evolutionary lineages for the main vector of Leishmania guyanensis, Lutzomyia umbratilis (Diptera: Psychodidae), in the Brazilian Amazon

Lutzomyia umbratilis is the main vector of Leishmania guyanensis in the Brazilian Amazon and in neighboring countries. Previous biological and molecular investigations have revealed significant differences between L. umbratilis populations from the central Brazilian Amazon region. Here, a phylogeographic survey of L. umbratilis populations collected from nine localities in the Brazilian Amazon was conducted using two mitochondrial genes. Statistical analyses focused on population genetics, phylogenetic relationships and species delimitations. COI genetic diversity was very high, whereas Cytb diversity was moderate. COI genealogical haplotypes, population structure and phylogenetic analyses identified a deep genetic differentiation and three main genetic groups. Cytb showed a shallower genetic structure, two main haplogroups and poorly resolved phylogenetic trees. These findings, allied to absence of isolation by distance, support the hypothesis that the Amazon and Negro Rivers and interfluves are the main evolutionary forces driving L. umbratilis diversification. The main three genetic groups observed represent three evolutionary lineages, possibly species. The first lineage occurs north of the Amazon River and east of Negro River, where Le. guyanensis transmission is intense, implying that L. umbratilis is an important vector there. The second lineage is in the interfluve between north of Amazon River and west of Negro River, an area reported to be free of Le. guyanensis transmission. The third lineage, first recorded in this study, is in the interfluve between south of Amazonas River and west of Madeira River, and its involvement in the transmission of this parasite remains to be elucidated.

Clinical and epidemiological profiles of patients with American cutaneous leishmaniasis from the states of Pernambuco and Amazonas, Brazil

INTRODUCTION:

Brazil has a high number of cases of American cutaneous leishmaniasis (ACL) in the north and northeast regions. Therefore, continuous surveillance of environmental and socioeconomic factors in endemic areas is needed to develop strategic control measures. This study aimed to describe the clinical and epidemiological profiles of patients with ACL.

METHODS:

All patients were from the states of Amazonas and Pernambuco, and examinations were carried out between 2015 and 2018. All patients had a clinical and epidemiological history compatible with ACL after positive diagnostic tests. Information obtained from medical records included gender, employment activity, level of education, age, and number and sites of lesions.

RESULTS:

A total of 213 patients were included, of whom 30.98% were female and 69.02% were male. The main employment activity was agriculture (27.56%). The most common level of education was elementary (62.42%). The average age was approximately 39 years. The majority of the patients presented only with one lesion (54.87%), and legs/feet were the most commonly affected area (48.25%), followed by the arms/hands (44.75%).

CONCLUSIONS:

These data demonstrated that irrespective of the patients’ places of origin, interventions need to be focused on men of economically productive age, in view of the high risk of exposure to the vector in this group. Education activities need to be directed to farmers about the importance of protection against ACL vectors during work. Such information must also be directed to employers as a way of implementing and maintaining appropriate working conditions and stepping up vector control.

Detection of Leishmania DNA in Sand Flies (Diptera: Psychodidae) From a Cutaneous Leishmaniasis Outbreak Area in Northeastern Brazil

Cutaneous leishmaniasis (CL) by Leishmania braziliensis Vianna (Kinetoplastida: Trypanosomatidae) is a widespread disease in the western hemisphere and Brazil is the country reporting the majority of the human cases each year. Several phlebotomine sand flies have been regarded as putative or proven vectors of L. braziliensis and multiple vectors may be involved in the transmission of this parasite in the same endemic foci. In this study, we tested a subset of female phlebotomine sand flies collected in the frame of a previous study conducted in a military training camp, where outbreaks of CL by L. braziliensis have sporadically been reported. In total, 1,807 female phlebotomine sand flies were tested (individually or in pools) by real-time PCR and a minimum infection rate of 0.9% (95% CI: 0.6-1.5%) was detected. Positive females belonged to the species Psychodopygus complexus (Mangabeira) or Psychodopygus wellcomei Fraiha, Shaw & Lainson (females of these species are morphologically indistinguishable), Trichopygomyia longispina (Mangabeira), and Sciopemyia sordellii (Shannon & Del Ponte) (Diptera: Psychodidae). By restriction enzyme analysis, 13 samples (nine of Ty. longispina, two of Ps. complexus/wellcomei, and two of Sc. sordellii) presented a HaeIII restriction profile identical to L. braziliensis. The results of this study reinforce the notion that multiple vectors may be involved in the transmission of L. braziliensis in a single focus, ultimately making the epidemiological picture more complex than currently recognized.

Morphological Description of the Immature Stages of Nyssomyia umbratilis (Ward & Frahia) (Diptera: Psychodidae: Phlebotominae), the Main Vector of Leishmania guyanensis Floch (Kinetoplastida: Trypanosomatidae) in the Brazilian Amazon Region

Nyssomyia umbratilis (Ward & Frahia) is the main vector of Leishmania guyanensis in the Brazilian Amazon region, where it is widely distributed. Studies have hypothesized that this phlebotomine is part of a cryptic species complex, spatially delimited by the Amazonian river systems, and with different transmission potential of L. guyanensis. In the present study, the immature stages of N. umbratilis are described from laboratory-reared specimens originating from the states of Amazonas and Pará, Brazil. Based on scanning electron and optical microscopy examinations, fine morphological structures (eggshell, setae, and mouthparts of larvae and pupae) are presented. A new form of sandfly pupae sexing (non-invasive) is also provided. The correct identification of insect is extremely important for the epidemiology of certain diseases. However, only the morphological characters of adult can be insufficient to separate accurately the closely related species. It is expected that the present description may contribute to solve the taxonomic problem involving N. umbratilis.

Leishmania naiffi and Leishmania guyanensis reference genomes highlight genome structure and gene evolution in the Viannia subgenus

The unicellular protozoan parasite Leishmania causes the neglected tropical disease leishmaniasis, affecting 12 million people in 98 countries. In South America, where the Viannia subgenus predominates, so far only L. (Viannia) braziliensis and L. (V.) panamensis have been sequenced, assembled and annotated as reference genomes. Addressing this deficit in molecular information can inform species typing, epidemiological monitoring and clinical treatment. Here, L. (V.) naiffi and L. (V.) guyanensis genomic DNA was sequenced to assemble these two genomes as draft references from short sequence reads. The methods used were tested using short sequence reads for L. braziliensis M2904 against its published reference as a comparison. This assembly and annotation pipeline identified 70 additional genes not annotated on the original M2904 reference. Phylogenetic and evolutionary comparisons of L. guyanensis and L. naiffi with 10 other Viannia genomes revealed four traits common to all Viannia: aneuploidy, 22 orthologous groups of genes absent in other Leishmania subgenera, elevated TATE transposon copies and a high NADH-dependent fumarate reductase gene copy number. Within the Viannia, there were limited structural changes in genome architecture specific to individual species: a 45 Kb amplification on chromosome 34 was present in all bar L. lainsoni, L. naiffi had a higher copy number of the virulence factor leishmanolysin, and laboratory isolate L. shawi M8408 had a possible minichromosome derived from the 3' end of chromosome 34. This combination of genome assembly, phylogenetics and comparative analysis across an extended panel of diverse Viannia has uncovered new insights into the origin and evolution of this subgenus and can help improve diagnostics for leishmaniasis surveillance.

Lutzomyia umbratilis from an area south of the Negro River is refractory to in vitro interaction with Leishmania guyanensis

BACKGROUND

Lutzomyia umbratilis, the vector for Leishmania guyanensis in northern South America, has been found naturally infected with L. guyanensis only in areas north of the Negro and Amazon rivers. While populations of this sand fly species are also found in areas south of these rivers, these populations have never been reported to be infected and/or transmitting L. guyanensis. However, no studies on the corresponding host-parasite interactions are available.

OBJECTIVES

This study evaluated the interaction between Lu. guyanensis promastigotes and field-collected Lu. umbratilis sand flies from Rio Preto da Eva and Manacapuru, which are located to the north and south, respectively, of the Negro River.

METHODS

Procyclic and metacyclic attachment was quantified using an in vitro system.

FINDINGS

Low attachment of parasites to the midguts of insects collected from Manacapuru was detected. Conversely, greater binding of metacyclic parasites was observed in the midguts of insects collected from Rio Preto da Eva, and this attachment was more pronounced than that observed for procyclics (p < 0.03).

MAIN CONCLUSIONS

The Lu. umbratilis population from an area south of the Negro River has lower in vitro interaction with L. guyanensis. The higher attachment of L. guyanensis to midguts of insects from Rio Preto da Eva may suggest better vector competence. These findings are in accordance with previously reported epidemiological information of American cutaneous leishmaniasis (ACL) transmission in the Amazon.

Analysis of the genetic structure of allopatric populations of Lutzomyia umbratilis using the period clock gene

In South America, Lutzomyia umbratilis is the main vector of Leishmania guyanensis, one of the species involved in the transmission of American tegumentary leishmaniasis. In Brazil, L. umbratilis has been recorded in the Amazon region, and an isolated population has been identified in the state of Pernambuco, Northeastern region. This study assessed the phylogeographic structure of three allopatric Brazilian populations of L. umbratilis. Samples of L. umbratilis were collected from Rio Preto da Eva (north of the Amazon River, Amazonas), from Manacapuru (south of the Amazon River), and from the isolated population in Recife, Pernambuco state. These samples were processed to obtain sequences of the period gene. Phylogenetic analysis revealed the presence of two distinct monophyletic clades: one clade comprised of the Recife and Rio Preto da Eva samples, and one clade comprised of the Manacapuru samples. Comparing the Manacapuru population with the Recife and Rio Preto da Eva populations revealed high indices of interpopulational divergence. Phylogenetic analysis indicated that geographical distance and environmental differences have not modified the ancestral relationship shared by the Recife and Rio Preto da Eva populations. Genetic similarities suggest that, in evolutionary terms, these populations are more closely related to each other than to the Manacapuru population. These results confirm the existence of an L. umbratilis species complex composed of at least two incipient species.

Phenotypic and genotypic variations among three allopatric populations of Lutzomyia umbratilis, main vector of Leishmania guyanensis

BACKGROUND

In South America, Lutzomyia umbratilis is the main vector of Leishmania guyanensis, one of the species involved in the transmission of American tegumentary leishmaniasis. In Brazil, L. umbratilis has been recorded in the Amazon region, and in the state of Pernambuco, Northeastern region, where an isolated population has been identified. This study assessed the phylogeographic structure and size and shape differences of the wing of three Brazilian populations.

METHODS

Samples of L. umbratilis were collected from Rio Preto da Eva (north of the Amazon River, Amazonas), from Manacapuru (south of the Amazon River), and from the isolated population in Recife, Pernambuco state. These samples were processed to obtain sequences of the Cytochrome Oxidase I mitochondrial gene. Geometrics morphometry analysis of the right wing shape of the three populations was made using discriminate canonical analysis.

RESULTS

Phylogenetic analysis revealed the presence of two distinct monophyletic clades: one clade comprised of the Recife and Rio Preto da Eva samples, and the other clade comprised of the Manacapuru samples. Comparing the Manacapuru population with the Recife and Rio Preto da Eva populations generated high indices of interpopulational divergence. Geometric morphometry analysis indicated two distinct groups between the studied populations. Canonical variate analysis of wing shape indicated that Rio Preto da Eva population is significantly closer to Recife population, and both populations were genetically distant from Manacapuru.

CONCLUSION

The polymorphic sites and geometric morphometry analysis indicate that the distance, lack of continuity and environmental differences have not modified the ancestral relationship between Recife and Rio Preto da Eva populations. The genetic and morphological similarities shared by the Recife and Rio Preto da Eva populations suggest that these populations are more closely related evolutionarily. These results confirm the existence of an L. umbratilis species complex in the North and Northeast regions.

Phlebotomine sandflies (Diptera: Psychodidae) of the Atlantic forest in Recife, Pernambuco state, Brazil: the species coming to human bait, and their seasonal and monthly variations over a 2-year period

In a study of the phlebotomine sandflies (Diptera: Psychodidae) in a forest reserve in Recife, Pernambuco state, north-eastern Brazil, the sandflies landing on human bait between 1.00 and 1.42 h after sunset were collected weekly for 2 years. Although 10,287 sandflies of 10 Lutzomyia species were collected, almost all (96.5%) of the sandflies caught were Lu. umbratilis. This species and several others caught are potential vectors of some of the Leishmania parasites that cause human disease. The recorded landing rate for Lu. umbratilis peaked, at the high level of 333.3 flies/person-hour, during the collections made in May 2003.The relative rarity in the collections of males of some of the species caught probably indicates that these species do not lek on their bloodmeal sources. It is likely that the sizes of the local populations of species that are not very anthrophilic, such as Lu. flaviscutellata, are much larger than indicated by the collections made on human bait.

Lutzomyia umbratilis, the main vector of Leishmania guyanensis, represents a novel species complex?

BACKGROUND

Lutzomyia umbratilis is an important Leishmania guyanensis vector in South America. Previous studies have suggested differences in the vector competence between L. umbratilis populations situated on opposite banks of the Amazonas and Negro Rivers in the central Amazonian Brazil region, likely indicating a species complex. However, few studies have been performed on these populations and the taxonomic status of L. umbratilis remains unclear.

METHODOLOGY/PRINCIPAL FINDINGS

Phylogeographic structure was estimated for six L. umbratilis samples from the central Amazonian region in Brazil by analyzing mtDNA using 1181 bp of the COI gene to assess whether the populations on opposite banks of these rivers consist of incipient or distinct species. The genetic diversity was fairly high and the results revealed two distinct clades ( = lineages) with 1% sequence divergence. Clade I consisted of four samples from the left bank of the Amazonas and Negro Rivers, whereas clade II comprised two samples from the right bank of Negro River. No haplotypes were shared between samples of two clades. Samples within clades exhibited low to moderate genetic differentiation (F(ST) = -0.0390-0.1841), whereas samples between clades exhibited very high differentiation (F(ST) = 0.7100-0.8497) and fixed differences. These lineages have diverged approximately 0.22 Mya in the middle Pleistocene. Demographic expansion was detected for the lineages I and II approximately 30,448 and 15,859 years ago, respectively, in the late Pleistocene.

CONCLUSIONS/SIGNIFICANCE

The two genetic lineages may represent an advanced speciation stage suggestive of incipient or distinct species within L. umbratilis. These findings suggest that the Amazonas and Negro Rivers may be acting as effective barriers, thus preventing gene flow between populations on opposite sides. Such findings have important implications for epidemiological studies, especially those related to vector competence and anthropophily, and for vector control strategies. In addition, L. umbratilis represents an interesting example in speciation studies.

Description of three practical and inexpensive devices for the collection of mosquitoes and other small insects

Three new devices for collecting and maintaining mosquitoes and other small insects are described. A suction tube, composed of two pieces of plastic transparent tube, the narrower fitted in the wider, with the mouth protected by the use of voile, is cheap and practical and can be transported around the neck. A 900-ml plastic transparent box is utilized for the restraint of sucked insects and, with the adaptation of two pieces of plastic tube, as a suction chamber.

Comparative biology of two populations of Lutzomyia umbratilis (Diptera: Psychodidae) of Central Amazonia, Brazil, under laboratory conditions

Lutzomyia umbratilis is the main vector of cutaneous leishmaniasis due to Leishmania guyanensis in northern South America. It has been found naturally infected with this species of Leishmania only east of the Rio Negro and north of the Rio Amazonas. However, populations of this sand fly species are also present in areas south of the Amazon river system, which may act as a geographical barrier to the Leishmania guyanensis cycle. With the aim of looking for possible biological differences between populations of L. umbratilis from each side of this river system, their biology in the laboratory was investigated. Progenitors collected on tree bases in Manaus and Manacapuru (east and west, respectively, of the Rio Negro) were reared in the laboratory. Results from observations of the life cycle, fecundity, fertility, and adult longevity at 27 degrees C and 92% RH were analyzed by descriptive statistics and z, t, U, and chi2 tests. Although the Manaus and Manacapuru colonies showed a longer developmental time than most Lutzomyia species reared at similar temperatures, length of time of egg and 4th instar larva of the two populations differed significantly (p < 0.01). Females of the latter retained significantly (p < 0.001) less mature oocytes, and the general productivity (% adults from a known number of eggs) of the colony was significantly (p < 0.01) higher than that of the former. These results show that the L. umbratilis population of Manaus is more productive, and thus a better candidate for future mass-rearing attempts. The two populations differ in their life cycle, fecundity, fertility, adult longevity, and emergence. These differences may reflect some divergence of intrinsic biological features evolved as a result of their geographical isolation by the Rio Negro. It is expected that further investigations on morphometry, cuticular hydrocarbon, isoenzyme, molecular and chromossomal analyses, infection, and cross-mating experiments with these and other allopatric populations of both margins of the Amazon river system will help reveal whether or not L. umbratilis has genetically diverged into two or more reproductively isolated populations of vectors or non-vectors of Leishmania guyanensis.

Leishmaniose tegumentar americana: histórico, epidemiologia e perspectivas de controle

A Leishmaniose Tegumentar Americana (LTA) é uma doença causada por protozoários do gênero Leishmania, transmitida ao homem pela picada de mosquitos flebotomíneos (Ordem Diptera; Família Psychodidae; Sub-Família Phlebotominae). No Brasil existem atualmente 6 espécies de Leishmania responsáveis pela doença humana, e mais de 200 espécies de flebotomíneos implicados em sua transmissão. Trata-se de uma doença que acompanha o homem desde tempos remotos e que tem apresentado, nos últimos 20 anos, um aumento do número de casos e ampliação de sua ocorrência geográfica, sendo encontrada atualmente em todos os Estados brasileiros, sob diferentes perfis epidemiológicos. Estima-se que, entre 1985 e 2003, ocorreram 523.975 casos autóctones, a sua maior parte nas regiões Nordeste e Norte do Brasil. Neste estudo, são discutidos aspectos relacionados ao tratamento e ao controle dessa doença, assim como também as dificuldades para a implementação dessas medidas. São apontadas alternativas que passam pela estruturação dos serviços de saúde, com respeito ao diagnóstico, no desenvolvimento de drogas de aplicação tópica ou por via oral, no desenvolvimento de vacinas, no controle diferenciado de vetores e no aprofundamento de estudos relacionados à biologia celular do parasita.

Estratificação vertical da fauna de flebótomos (Diptera, Psychodidae) numa floresta primária de terra firme da Amazônia Central, Estado do Amazonas, Brasil

Estudos sobre a estratificação vertical da fauna de flebótomos, foram realizados numa floresta primária de terra firme, da Estação Experimental de Silvicultura Tropical - Instituto Nacional de Pesquisas da Amazônia, durante os meses de outubro de 1998 a março de 1999. Utilizando-se armadilhas luminosas CDC, colocadas a 1, 10 e 20 metros de altura do solo, foram coletados 2.859 flebótomos, pertencentes a dois gêneros, Lutzomyia (99,93 %) e Brumtomyia (0,07%), abrangendo 38 espécies. Dentro do gênero Lutzomyia, os sub-gêneros mais representados foram Nyssomyia, com 43,4%, e Psychodopygus com 22,8%. As espécies Lutzomyia umbratilis, L. anduzei, L. rorotaensis, L. trichopyga e L. olmeca nociva, foram dominantes a 1m de altura, enquanto que L. davisi, L. infraspinosa, L. umbratilis, L. trichopyga e L. anduzei, foram dominantes a 10m. As espécies L. anduzei, L. tuberculata, L. dendrophyla e L. dreisbachi foram mais abundantes a 20m. L. umbratilis, presente nos três níveis de estratificação vertical, é dotada de alta importância epidemiológica como vetora da Leishmania (Viannia) guyanensis.