Phlebotominae in peri‐domestic and forest environments inhabited by Alouatta caraya in northeastern Argentina

Multiple species of Phlebotominae are vectors of Leishmania (Protozoa: Trypanosomatidae), which causes visceral leishmaniasis (VL) and cutaneous leishmaniasis (CL). To describe the Phlebotominae (Diptera: Psychodidae) related to the environments of black and gold howler monkeys Alouatta caraya (Humbodlt, 1812) (Primates: Atelidae), potential vectors were sampled in different landscapes and vertical strata of sleeping trees. Phlebotomine captured between December 2011 and March 2012 (2365 individuals) belonged to eight species, of which Nyssomyia neivai (Pinto, 1926) (61.4%) and Migonemyia migonei (França, 1920) (18.73%) were the most abundant, and Ny. withmani was recorded for the first time in the Chaco province. In the ‘peri‐domestic’ landscape, the phlebotomine were mainly captured in henhouses (78.7%), whereas the tree canopy in ‘rural’ and ‘wild’ landscapes yielded 31.2% and 29.1% of the phlebotomine, respectively. A significant association between the type of landscape and the species of phlebotomine was observed by multivariate analysis. Lutzomyia longipalpis (Lutz & Neiva, 1912) and Mg. migonei were associated with ‘peri‐domestic’ landscape, and Ny. neivai was associated with the ‘wild’ landscape. The results of this prospective study suggest that the interaction between phlebotomine and A. caraya could be a key factor with respect to understanding the epidemiology of leishmaniasis.     

Ecological interactions among phlebotomines (Diptera: Psychodidae) in an agroforestry environment of northeast Brazil

Phlebotomine vectors transmit parasites and can cause visceral leishmaniasis (VL) or cutaneous leishmaniasis (TL). Phlebotomine females are hematophagous but need to ingest carbohydrates, possibly promoting the development of protozoan parasites in their digestive tract. The present study evaluated the species composition and abundance across several habitats in a metropolitan landscape, as well as associations among phlebotomines, plants, and local climatic parameters. Three consecutive monthly collections were carried out in an Atlantic Forest fragment, using CDC light traps in peridomestic areas and cashew, coconut, and mango tree. plantations. Eight species of phlebotomine were captured: Evandromyia evandroi, Lutzomyia longipalpis, Psathyromyia shannoni, Sciopemyia sordellii, Evandromyia walkeri, Psychodopygus wellcomei, Nyssomyia whitmani, and Nyssomyia intermedia, primarily from the forest environment. L. longipalpis was confirmed as a species adapted to anthropic environments, while P. wellcomei was shown to be predominately forest‐dwelling. Phlebotomines exhibited diversified food consumption patterns in relation to carbohydrate sources. They fed on both native and exotic species of arboreal and shrubby vegetables and gramineous plants.     

Morphometric and molecular differentiation of Phlebotomus (Phlebotomus) sandflies

The closely related sandfly species of the subgenus Phlebotomus namely, Phlebotomus papatasi (Scopoli, 1786), Phlebotomus duboscqi Neveu‐Lemair, 1906 and Phlebotomus bergeroti Parrot, 1934 (Diptera: Psychodidae), are major vectors of Leishmania major (Kinetoplastida: Trypanosomatidae), the causative agent of cutaneous leishmaniasis in the Old World. Although allopatric in most of their distribution, the three species exist sympatrically in many places in central and eastern Sudan. Males of the three species can be distinguished using morphological characters; however, females are much harder to identify, thus complicating epidemiological studies. We carried out a morphometric and a molecular study to determine reliable morphological features and develop a polymerase chain reaction (PCR) assay for distinguishing females of these species. Males and females from each species were collected from sites in Sudan, East Africa and from one site in Mali, West Africa. Males were analysed morphologically and 20 characters and 10 character ratios were used in a stepwise discriminant analysis. This led to the identification of four characters with high discriminant loading scores sufficient for accurate male species identification. Male DNA was then used for the development of a PCR‐based species diagnostic based on the second internal transcribed spacer (ITS2) of the ribosomal DNA. A set of four primers was developed to generate fragment sizes that are specific to each species and can reliably identify females as well as hybrid DNA. Both the morphometric and the molecular findings of this study have important applications for studies of the epidemiology of cutaneous leishmaniasis.     

Detection of Leishmania amazonensis and Leishmania braziliensis in Culicoides (Diptera,Ceratopogonidae) in an endemic area of cutaneous leishmaniasis in the Brazilian Amazonia

Biting midges in the genus Culicoides act as vectors of arboviruses throughout the world and as vectors of filariasis in Latin America, the Caribbean, and parts of Africa. Although Culicoides spp. are currently not considered to be vectors of Leishmania protozoa, the high abundance of biting midges in areas with active cutaneous leishmaniasis transmission points to the possibility of Culicoides infection by these pathogens. We used PCR to test captured Culicoides species for natural infection with Leishmania spp. We tested 450 Culicoides females, divided into 30 pools of 15 individuals each, as follows: nine pools of C. foxi (135 specimens), seven pools of C. filariferus (105), seven pools of C. insignis (105), five pools of C. ignacioi (75), and two pools of C. flavivenula (30). PCR confirmed the presence of Leishmania braziliensis DNA in C. ignacioi (0.14%), C. insignis (0.14%), and C. foxi (0.11); and Le. amazonensis DNA in C. filariferus (0.14%) and C. flavivenula (0.50%). We conclude that these Culicoides species can be naturally infected, but vector competence and transmission capability must be confirmed in future studies. Our results warrant further investigation into the role of these biting midge species in the leishmaniasis epidemiological cycle.     

Ecology of phlebotomine sand flies in the rural community of Mont Rolland (Thiès region, Senegal): area of transmission of canine leishmaniasis

Background

Different epidemiological studies previously indicated that canine leishmaniasis is present in the region of Thiès (Senegal). However, the risks to human health, the transmission cycle and particularly the implicated vectors are unknown.

Methodology/Principal Findings

To improve our knowledge on the population of phlebotomine sand flies and the potential vectors of canine leishmaniasis, sand flies were collected using sticky traps, light traps and indoor spraying method using pyrethroid insecticides in 16 villages of the rural community of Mont Rolland (Thiès region) between March and July 2005. The 3788 phlebotomine sand flies we collected (2044 males, 1744 females) were distributed among 9 species of which 2 belonged to the genus Phlebotomus: P. duboscqi (vector of cutaneous leishmaniasis in Senegal) and P. rodhaini. The other species belonged to the genus Sergentomyia: S. adleri, S. clydei, S. antennata, S. buxtoni, S. dubia, S. schwetzi and S. magna. The number of individuals and the species composition differed according to the type of trap, suggesting variable, species-related degrees of endophily or exophily. The two species of the genus Phlebotomus were markedly under-represented in comparison to the species of the genus Sergentomyia. This study also shows a heterogeneous spatial distribution within the rural community that could be explained by the different ecosystems and particularly the soil characteristics of this community. Finally, the presence of the S. dubia species appeared to be significantly associated with canine leishmaniasis seroprevalence in dogs.

Conclusions/Significance

Our data allow us to hypothesize that the species of the genus Sergentomyia and particularly the species S. dubia and S. schwetzi might be capable of transmitting canine leishmaniasis. These results challenge the dogma that leishmaniasis is exclusively transmitted by species of the genus Phlebotomus in the Old World. This hypothesis should be more thoroughly evaluated.     

Leishmaniasis in Bolivia. II. The involvement of Psychodopygus yucumensis and Psychodopygus llanosmartinsi in the selvatic transmission cycle of Leishmania braziliensis braziliensis in a lowland subandean region

An epidemiological survey of the vectors of cutaneous leishmaniasis ("espúndia" type) was carried out in the Alto Beni region of Bolivia, an area of Andean foothills at the Eastern limit of the Amazonian lowlands. The climate is typical wet tropical (15 degrees S latitude). Anthropophilic phlebotomine sandfly species were sampled at 20 sites, all forested. The importance of species from the Psychodopygus group, already suspected as a vector in the transmission of Leishmania from the braziliensis complex, was confirmed by: the aggressiveness and diversity of the species encountered (83% of catches, nine species), the discovery of a new anthropophilic species, P. yucumensis and the isolation of a strain of Leishmania braziliensis braziliensis indistinguishable from human strains from the same area, from two species, P. llanosmartinsi and P. yucumensis.     

Molecular detection of Leishmania (Sauroleishmania) tarentolae in human blood and Leishmania (Leishmania) infantum in Sergentomyia minuta: unexpected host-parasite contacts

The detection of atypical Kinetoplastida in vertebrate hosts and vectors might suggest unexpected host-parasite contacts. Aside to major vectors of Leishmania (Leishmania) infantum in Italy (e.g. Phlebotomus perniciosus and Phlebotomus perfiliewi), the sand fly fauna also includes Sergentomyia minuta, herpetophilic and proven vector of Leishmania (Sauroleishmania) tarentolae, in which records of blood meal on mammals and detection of L. infantum DNA are increasing. This study was conducted in Central Italy aiming to molecularly detect potential atypical Leishmania host-vector contacts. Detection of Leishmania spp. DNA was performed by polymerase chain reaction (SSU rRNA, ITS1 targets) on field-collected sand fly females (N = 344), blood samples from humans (N = 185) and dogs (N = 125). Blood meal identification was also performed on engorged sand flies. Leishmania spp. DNA was found in 13.1% sand flies, 3.7% humans and 14.4% dogs. Sequence analysis identified L. infantum in S. minuta (4.4%), P. perniciosus (9.1%), humans (2.2%) and dogs (14.4%). Leishmania tarentolae was detected in S. minuta (12.6%), P. perfiliewi (6.6%) and human (1.6%) samples. Of 28 S. minuta examined for blood meal, 3.6 and 21.4% scored positive for human and lizard DNA, respectively. These results indicate the importance of one-health approach to explore new potential routes of transmission of leishmaniasis involving S. minuta.     

Leishmania strains causing self-healing cutaneous leishmaniasis have greater susceptibility towards oxidative stress

Abstract

The survival of Leishmania parasites within macrophages is influenced by generation of free radicals. To establish whether generation of free radicals influenced chemotherapeutic response, promastigotes from isolates causing self-healing or delayed/non-self-healing cutaneous leishmaniasis (CL) or visceral leishmaniasis (VL) were evaluated for their susceptibility to nitric oxide (NO), antimony and miltefosine. In a self-healing CL strain of Leishmania major (5ASKH), susceptibility to NO and antimony was higher than other species. Likewise, a Leishmania amazonensis strain, M2269, showed greater susceptibility to NO and antimony than other species but no such correlation was observed with miltefosine. Additionally, 5ASKH and M2269 showed poorer free radical scavenging capacity as also their thiol levels were lower than species causing VL. Collectively, our study suggests that self-healing isolates tend to be more susceptible to oxidative stress.     

Bionomics of phlebotomine sand flies (Diptera: Psychodidae) in the province of Al-Baha, Saudi Arabia

The bionomics of phlebotomine sand flies (Diptera: Psychodidae) were studied for two successive years (January 1996-December 1997) at 12 collecting stations representing six sectors of the province of Al-Baha, Saudi Arabia. The predominant species was Phlebotomus bergeroti (41.7%), followed by lesser numbers of Phlebotomus sergenti (11%), Phlebotomus arabicus (10.6%), Sergentomyia tiberiadis (10.5%), Phlebotomus papatasi (10.2%), Sergentomyia antennata (9.6%), Phlebotomus alexandri (3%), Phlebotomus orientalis (2.3%) and Sergentomyia clydei (1.1%). The distribution of the collected species including species that are elsewhere known to act as vectors of human cutaneous leishmaniasis were distributed across different altitudes in Al-Baha. P. bergeroti, P. papatasi and P. arabicus were more abundant indoors; however, P. sergenti was more abundant outdoors. Sand fly populations exhibited three patterns of seasonal abundance in terms of their monthly activity. P. bergeroti, P. sergenti and P. arabicus were found to be naturally infected with Leishmania-like flagellates at an infection rate of 0.2%.     

Identification of phlebotomine sand flies (Diptera: Psychodidae) from leishmaniasis endemic areas in southeastern Mexico using DNA barcoding

Leishmaniasis, a vector‐borne disease transmitted to humans through the bite of phlebotomine sand flies, is of public health significance in southeastern Mexico. Active and continuous monitoring of vectors is an important aspect of disease control for the prediction of potential outbreaks. Thus, the correct identification of vectors is paramount in this regard. In this study, we employed DNA barcoding as a tool for identifying phlebotomine sand flies collected in localized cutaneous leishmaniasis endemic areas of Quintana Roo, Mexico. Specimens were collected using CDC light and Shannon traps as part of the Mexican Ministry of Health surveillance program. DNA extraction was carried out using a nondestructive protocol, and morphological identification based on taxonomic keys was conducted on slide‐mounted specimens. Molecular taxonomic resolution using the 658‐bp fragment of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene was 100% congruent with the morphological identification. Seven species were identified: Lutzomyia cruciata (Coquillett 1907), Lutzomyia longipalpis (Lutz & Neiva 1912), Psathyromyia shannoni (Dyar 1929), Dampfomyia deleoni (Fairchild & Hertig 1947), Dampfomyia beltrani/steatopyga (Vargas & Díaz‐Nájera 1951), Bichromomyia olmeca olmeca (Vargas & Díaz‐Nájera, 1959), and Brumptomyia mesai (Sherlock 1962). Mean intraspecific divergence ranged from 0.12% to 1.22%, while interspecific distances ranged from 11.59% to 19.29%. Neighbor‐joining (NJ) analysis using the Kimura 2‐parameter model also showed specimens of the same species to be clustered together. The study provides the first cox1 sequences for three species of sand flies and indicates the utility of DNA barcoding for phlebotomine sand flies species identification in southeastern Mexico.     

Impact of meteorological and geographical factors on the distribution of Phlebotomus chinensis in northwestern mainland China

Phlebotomine sandflies (Diptera: Phlebotomidae) are vectors of the zoonotic disease leishmaniasis. To better understand the distribution of phlebotomine sandflies in order to facilitate control of leishmaniasis transmission, the present study explored the impacts of climate and landscape on local abundances of Phlebotomus chinensis in northwestern mainland China. Identification records were used to create a geodatabase for the locations at which P. chinensis had been collected in the region, and a regional‐scale map was developed to show the distribution of P. chinensis. Location data and data on environmental factors during the years in which the samples were collected were incorporated, and a presence‐only modelling method was used to evaluate the species' habitat preferences and to predict its potential distribution in northwestern mainland China. Jackknife analysis revealed that several meteorological variables, including maximum temperature in the warmest quarter, precipitation in the driest month, daily average temperature and daily precipitation, significantly affected the presence of this species. Moreover, the presence of P. chinensis was significantly associated with grassland and shrubland. Probability distributions using maximum entropy were used to map the distribution ranges of P. chinensis based on suitable habitats in northwestern mainland China. The models generated can be used to develop detailed strategies for the prevention and control of leishmaniasis.     

Assessing the importance of four sandfly species (Diptera: Psychodidae) as vectors of Leishmania mexicana in Campeche,Mexico

Localized cutaneous leishmaniasis represents a public health problem in many areas of Mexico, especially in the Yucatan Peninsula. An understanding of vector ecology and bionomics is of great importance in evaluations of the transmission dynamics of Leishmania parasites. A field study was conducted in the county of Calakmul, state of Campeche, during the period from November 2006 to March 2007. Phlebotomine sandfly vectors were sampled using Centers for Disease Control light traps, baited Disney traps and Shannon traps. A total of 3374 specimens were captured in the two villages of Once de Mayo (93.8%) and Arroyo Negro (6.1%). In Once de Mayo, the most abundant species were Psathyromyia shannoni, Lutzomyia cruciata, Bichromomyia olmeca olmeca and Psychodopygus panamensis (all: Diptera: Psychodidae). The Shannon trap was by far the most efficient method of collection. The infection rate, as determined by Leishmania mexicana‐specific polymerase chain reaction, was 0.3% in Once de Mayo and infected sandflies included Psy. panamensis, B. o. olmeca and Psa. shannoni. There were significant differences in human biting rates across sandfly species and month of sampling. Ecological niche modelling analyses showed an overall overlap of 39.1% for the four species in the whole state of Campeche. In addition, the finding of nine vector–reservoir pairs indicates a potential interaction. The roles of the various sandfly vectors in Calakmul are discussed.     

The application of random amplified polymorphic DNA for sandfly species identification

Abstract. We have applied the recently developed Random Amplified Polymorphic DNA (RAPD) method to produce species-specific, DNA profiles for two sympatric, Venezuelan sandfly species, thought to be the vectors responsible for recent outbreaks of cutaneous and mucocutaneous leishmaniasis in the Andean State of Tachira. Moreover, within the profile, it was possible to identify a diagnostic DNA band for Lu.youngi of 0.32 kb. Results showed that the size of this diagnostic DNA band remained constant and did not vary with sex or geographical distribution.     

<Emphasis Type="Italic">In vitro</Emphasis> antileishmanial activity of <Emphasis Type="Italic">Aloe vera</Emphasis> leaf exudate: A potential herbal therapy in leishmaniasis

Aloe vera has wide spread use in health products, and despite several reports on the whole plant and inner gel, little work has been performed on the leaf exudate. Our aim was to evaluate the in vitro efficacy of Aloe vera leaf exudate (AVL) in leishmaniasis. Irrespective of the disease manifestation, promastigotes from strains responsible for cutaneous, mucocutaneous, and visceral leishmaniasis were susceptible to AVL and their IC₅₀ ranged from 100 to 180 μg/ml. In axenic amastigotes cultured from a L. donovani strain 2001 responsible for visceral leishmaniasis, the IC₅₀ was 6.0 μg/ml. AVL caused activation of host macrophages evident by an increased release of members of reactive oxygen species that was attenuated by preincubation with free radical scavengers. Collectively, our data indicates that AVL, via its direct leishmanicidal activity which can be further enhanced by activation of host macrophages, is an effective antileishmanial agent meriting further pharmacological investigations.     

Nyssomyia intermedia (Lutz & Neiva, 1912) and Nyssomyia neivai (Pinto, 1926) (Diptera: Psychodidae: Phlebotominae) geographical distribution and epidemiological importance

Nyssomyia intermedia (Lutz & Neiva 1912) and N. neivai (Pinto 1926) are possible vectors of tegumentary leishmaniasis in some regions of Brazil. Further, the latter was until recently, considered a junior synonym of the former. This study has the purpose of updating our knowledge of the geographical distribution of these species, based on specimens deposited at the collection of the Centro de Pesquisas René Rachou-Fiocruz, Faculdade de Saúde Pública-Universidade de S?o Paulo, and on data presented by literature as also to associate this distribution with the cutaneous leishmaniasis cases reported. It has been reported that N. intermedia occurs in the states of the Northeastern Region, in Rio de Janeiro, Espírito Santo, on the northern coast of S?o Paulo, in eastern Minas Gerais, Mato Grosso do Sul, and Goiás, close to the border with Minas Gerais and Bahia. N. neivai occurs in the Southern Region, southern coast and in western S?o Paulo, southern and western Minas Gerais, southern Goiás, and southern Pará, beyond Argentina, Bolivia, and Paraguay. It is important to highlight that N. intermedia and N. neivai occur in sympatry in Minas Gerais and S?o Paulo. N. intermedia or N. neivai are predominant or are captured abundantly in several cutaneous leishmaniasis foci in the Southeastern and Southern regions of Brazil.     

The insect transmission of an isolate of okra mosaic virus occurring in Nigeria

Three species of chrysomelid beetles (Podagrica sjostedti, P. uniforma and Syagrus calcaratus) transmitted a Nigerian isolate of okra mosaic virus (OMV) to okra (Abelmoschus esculentus) and green gram (Vigna aureus), two (P. uniforma and S. calcaratus) also to cotton (Gossypium hirsutum) and one (P. uniforma) also to cowpea. Using one viruliferous beetle per test plant, P. sjostedti, P. uniforma and S. calcaratus infected 63, 68 and 34% of test plants respectively. Virus was retained by these vectors for up to 6 days. Whiteflies (Bemisia tabaci) also transmitted OMV, although much less efficiently than the beetle vectors.     

Bionomics of phlebotomine sandflies in the Galilee focus of cutaneous leishmaniasis in northern Israel

The bionomics of phlebotomine sandflies (Diptera: Psychodidae) were studied for three years (2001-2003) in the Galilee focus of cutaneous leishmaniasis in northern Israel, where the causative Leishmania tropica (Kinetoplastida: Trypanosomatidae) is transmitted by Phlebotomus (Adlerius) arabicus Theodor and Phlebotomus (Paraphlebotomus) sergenti Parrot, comprising 22% and 8%, respectively, of the local sandfly fauna sampled by light traps. The predominant species overall was Phlebotomus (Larroussius) tobbi Adler & Theodor (51%) with lesser numbers of Phlebotomus (Adlerius) simici Theodor (11%), Phlebotomus (Larroussius) syriacus Adler & Theodor (5%), Phlebotomus (Larroussius) perfiliewi Perfil'ev (3%) and Phlebotomus (Phlebotomus) papatasi Scopoli (0.05%). Sandfly adult populations were prevalent from April to November and peaked between June and August, being more abundant through the summer in irrigated habitats, such as gardens and orchards, than in open grassland. Of the two cutaneous leishmaniasis vectors, P. sergenti preferred boulder mounds located at the outskirts of settlements, whereas P. arabicus was more abundant overall and near houses in particular. Females of all these sandfly species displayed a peak of activity after sunset (20.00-22.00 hours), whereas activity of males persisted longer through the night. Another slight increase in activity was noted before dawn (02.00-04.00 hours). Phlebotomus arabicus appears to be the main vector of L. tropica in the Galilee focus, due to its denser populations, more endophily and preference for peridomestic habitats than shown by P. sergenti in northern Israel.     

Studies on the behaviour and control of phlebotomine sandflies using experimental houses

Programmes for the control of phlebotomine sandflies (Diptera: Psychodidae), the vectors of leishmaniases, mainly target adults because larval breeding sites are generally unknown or inaccessible. To determine how blood‐questing sandfly females enter homes and to develop means for their control, an experimental house (EH) was constructed in a village endemic for cutaneous leishmaniasis. Initially, carbon dioxide (CO₂)‐baited suction traps were installed inside the EH to attract and capture sandflies. For other experiments, the windows of the EH were fitted with CO₂‐baited window entrance traps (WETs) that allow each window to be considered as a separate unit. The majority of captures inside the EH and in WETs consisted of Phlebotomus sergenti, a species that enters inhabited houses relatively infrequently. Analyses of collections in WETs and in sticky traps on external walls showed that sandflies entered windows having landed previously on the wall below or either side of the window. Shelves constructed below windows significantly reduced the numbers of sandflies that entered both the EH and inhabited houses. The lining of internal walls with insecticide‐impregnated fabric significantly increased mortality rates of sandflies captured inside the EH. To reduce the biting burden imposed by phlebotomine sandflies, several control measures must be integrated and sustained.     

Phlebotomus (Adlerius) halepensis vector competence for Leishmania major and Le. tropica

In Eurasia, phlebotomine sandflies of the subgenus Adlerius (Diptera: Psychodidae) comprise about 20 known species. Some are suspected vectors of visceral leishmaniasis (VL) and at least one species has been implicated as a vector of cutaneous leishmaniasis (CL). We tested Phlebotomus (Adlerius) halepensis Theodor (Jordan strain) for CL vector competence, compared with three standard vectors: Phlebotomus (Phlebotomus) duboscqi N-L. from Senegal, Phlebotomus (Paraphlebotomus) sergenti Parrot from Turkey and the Neotropical Lutzomyia longipalpis (L. & N) (Jacobina strain). Sandfly females were membrane-fed on amastigote suspensions of Leishmania major Y. & S. and Le. tropica (Wright) (Kinetoplastida: Trypanosomatidae) and examined for parasite development 3, 6 and 10 days post-infection. Phlebotomus halepensis showed high susceptibility to both leishmanias, supporting typical suprapylarian parasite development similar to the other vectors. Phlebotomus halepensis infection rates were approximately 90% for Le. major and approximately 80% for Le. tropica, with high parasite densities. Development of infections was relatively fast, colonizing the thoracic midgut by 6 days post-bloodmeal in every case and reaching the stomodeal valve in >80% of flies. In late-stage infections, 10 days post-bloodmeal, nearly all P. halepensis females had cardia and stomodeal valve filled with very high numbers of parasites and some Le. tropica-infected females had promastigotes in the pharynx and proboscis. Host choice experiments in the laboratory showed that P. halepensis females fed readily on rat or rabbit and preferred the human forearm. In view of its vector competence and partial anthropophily, we infer that P. halepensis is a potential vector of cutaneous as well as visceral leishmaniases.