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PubMed2002

The role of promastigote secretory gel in the origin and transmission of the infective stage of Leishmania mexicana by the sandfly Lutzomyia longipalpis.

Transmission of leishmaniasis is effected by a specific developmental stage, the metacyclic promastigote. The precursors of metacyclic promastigotes were a distinct subpopulation of parasites, identified for the first time as a new stage in the life-cycle and named leptomonad promastigotes. Microdissection of infected sandflies into 4 midgut regions and foregut allowed precursor-product relationships to be established for amastigote-procyclic promastigote, procyclic-nectomonad promastigote, nectomonad-leptomonad promastigote and leptomonad-metacyclic promastigote developmental switches. Metacyclic promastigotes occurred mainly in the thoracic midgut and cardia, coincident with the accumulation of a promastigote secretory gel (PSG) plug in these anterior regions. The gel-like plug was isolated from flies with mature infections and found to contain predominantly leptomonad promastigotes. The PSG plug also contained the majority (75%) of the total metacyclic promastigote population in the sandflies, which were concentrated at the anterior pole. The PSG plug was found to be the main site of metacyclogenesis, and acted as a reservoir of leptomonad promastigotes from which metacyclic forms differentiated and migrated forward to promote the infective potential of the fly. The PSG plug occluded and distorted the midgut, forcing the stomodeal valve open and affecting the feeding success of the sandflies, such that they experienced difficulty in taking a full meal. Collectively, these data support the role of the PSG in the transmission of leishmaniasis, by conditioning the midgut environment for metacyclogenesis and altering the feeding ability of infected sandflies.

Animals↗
PubMed1999

Associations of Phlebotomus orientalis and other sandflies with vegetation types in the eastern Sudan focus of kala-azar.

Abundances of Phlebotomus orientalis, P. papatasi (Diptera: Psychodidae) and other sandflies were investigated in relation to different types of vegetation associated with endemic foci of visceral leishmaniasis (kala-azar) in eastern Sudan. Sandfly collection sites were in Umsalala Village (Galabat Province) and Dinder National Park (Dinder Province). Sandfly species found in the area were P. orientalis, P. papatasi, Sergentomyia africana, S. antennata, S. clydei, S. schwetzi and S. squamipleuris. Among the types of trees in the Dinder area, P. orientalis was more abundant in forests dominated by Acacia seyal than where Combretum kordofanum, Balanites aegyptiaca, Hyphaena thaibaica or Ziziphus spinachristi were the dominant trees. At Umsalala, P. papatasi was more abundant in the village than at any site with dense vegetation, but P. orientalis was uncommon. Sergentomyia spp. were distributed fairly evenly amongst most types of vegetation investigated at both localities. The ecological distribution of sandflies and epidemiology of kala-azar in Sudan are discussed with emphasis on the association of P. orientalis with A. seyal woodlands.

Animals↗
PubMed1994

Sandflies in the Greater Athens region, Greece.

During the period from May to October 1992, a survey of phlebotomine sandflies was conducted in the Greater Athens region where cases of human and canine leishmaniasis occur. Using castor-oil paper traps, a total of 3015 sandflies were caught. Of the identified specimens, 1002 (34.1%) were Phlebotomus neglectus, 541 (18.4%) were P. papatasi, 182 (6.2%) were P. tobbi, 50 (1.7%) were P. simici, 30 (1.0%) were P. alexandri, 3(0.4%) were P. sergenti and 1122 (38.2%) were Sergentomyia minuta. The seasonal activity of most Phlebotomus species was bimodal, while that of S. minuta was unimodal. The population density of sandflies varied significantly in different localities; it was low in most of the stations and high in some stations in the outskirts. Among the potential vectors of Leishmania spp., P. neglectus and P. Papatasi were the most widespread species. The former species showed high density in 12 of the 70 sampled stations, while the latter in only 4. Hence, the risk of transmission of sandfly-borne diseases is still present in the Greater Athens region.

Animals↗
PubMed1991

Distribution of sandflies (Diptera: Psychodidae) in three vegetation habitats in the Marigat area, Baringo District, Kenya.

A total of 4,467 phlebotomine sandflies representing nine species and two genera were collected using polythene material coated with castor oil in three vegetation types in Marigat area from February to May 1986. Sandfly relative abundance was greatest in the closed-canopy forest (61% of total catch), followed by the open-canopy woodland (38%) and the thicket (1%). Nine species of sandflies were collected in both the closed-canopy forest and the open-canopy woodland. The thicket yielded only four species. The sandfly population in the vegetation was composed of Sergentomyia bedfordi (61%), S. antennatus (31%), S. ingrami (3%), S. schwetzi (2%), and S. africanus (1%). Plebotomus species rarely occurred in the study area. In the closed-canopy forest and the open-canopy woodland, female S. bedfordi were most abundant during the dry season, while males predominated during the wet period. Inversely, more male S. antennatus were collected during the dry season, while females predominated in the open-canopy woodland during the wet season. In the closed-canopy forest, male S. antennatus outnumbered the females during both dry and wet seasons. Both S. antennatus and S. bedfordi increased in abundance during the dry season.

Animals↗
PubMed2003

Epidemiological, clinical and laboratory aspects of sandfly fever.

PURPOSE OF REVIEW: Sandfly fever viruses are still a significant health problem in many regions of the world, such as Africa, the Mediterranean basin, the Middle East, and Central Asia. This review provides an update on the advances in knowledge about epidemiological, clinical, and laboratory aspects of infections caused by Toscana, Sicilian and Naples viruses. RECENT FINDINGS: Diagnosis of Toscana virus infection has been facilitated by new molecular methods and by immunoenzymatic tests based on the recombinant nucleoprotein. Gene analysis has allowed identification of circulating Toscana variants possibly involved in the protean pathomorphism and extreme variability of the clinical picture. New attention has been addressed to the antigenic properties of the viral proteins (the nucleoprotein N and the surface glycoproteins G1 and G2), in order to understand their immunogenetic role. High genetic divergence within the serocomplexes belonging to each of the Sicilian and the Naples viruses has suggested that infection with one genotype may not completely immunize against infection with all other genotypes in a given serocomplex. These findings could serve as a basis for vaccine development and may account for reports of multiple episodes of sandfly fever in the same host. Recently, the performance of analysis models based on weather data and reported vector surveys has allowed the prediction of the risk of acquiring sandfly infection in the endemic geographic areas. SUMMARY: Recent developments include a better knowledge of the epidemiological, clinical, and laboratory aspects of sandfly infection, while the search for effective drugs and vaccines is still in progress.

Animals↗
PubMed2004

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.

Animals↗
PubMed1992

Patterns of sandfly distribution in tropical forest: a causal hypothesis.

1. In tropical rain forest, phlebotomine sandflies (Diptera: Psychodidae), such as Lutzomyia vespertilionis and L.ylephiletor, have an aggregated distribution on their tree buttress diurnal resting sites, as studied during 1987-88 at Finca la Selva in the Caribbean lowlands of Costa Rica. 2. Experimental transfer of flies to trees not used as resting sites indicated that many apparently suitable sites remain unoccupied. 3. Observations of sandflies on the buttresses revealed that males and females are juxtaposed more frequently than expected by chance alone. Courtship behaviour by three of the four species of sandfly studied was observed on the buttresses. 4. It is suggested that the use of buttresses as swarming sites for mating behaviour is more likely to account for the observed distribution patterns of sandflies than their use of buttresses simply as diurnal resting sites.

Animals↗
PubMed1995

The relationship between CDC light-trap and human-bait catches of endophagic sandflies (Diptera: Psychodidae) in the Peruvian Andes.

A study was carried out in the Peruvian Andes to test the suitability of CDC light traps for monitoring changes in the human-landing rate of endophagic phlebotomine sandflies, following house-spraying with pyrethroid insecticide. On four pairs of consecutive nights, sandflies were caught inside eight sprayed and eight unsprayed houses, either by human bait or by CDC light traps. The sandflies collected were Lutzomyia verrucarum (97%) and Lu.peruensis (3%), both probable vectors of Leishmania peruviana, and the species composition was unaffected by house-spraying. A non-linear relationship was detected between light-trap and human-bait catches, but the relationship did not diverge significantly from linearity within the range of sandfly abundance found in most houses in the endemic area (i.e. between 3 and 200 sandflies/house-night), and did not differ significantly between sprayed and unsprayed houses. However, light trap catches had a significantly lower proportion of blood-fed females in sprayed than in unsprayed houses, probably due to an insecticidal effect on post-blood-feeding behaviour. The proportion of Lu. verrucarum was significantly higher in light trap than in human bait catches, indicating that Lu.peruensis is either more anthropophilic or less phototropic than Lu.verrucarum.

Animals↗
PubMed1995

Evaluation of deltamethrin-impregnated bednets and curtains against phlebotomine sandflies in Valle del Cauca, Colombia.

The effectiveness of bednets and curtains (nylon mesh 64 per cm2) impregnated with deltamethrin at 26 mg a.i./m2 in reducing the biting nuisance caused by three phlebotomine sandfly species: Lutzomyia columbiana, Lu.lichyi and the predominant Lu.youngi (Diptera: Psychodidae), was evaluated at La Guaira, a rural settlement in Valle de Cauca near Cali, Colombia. Pairs of volunteers collected sandflies under impregnated bednets, in rooms protected by impregnated curtains or in unprotected rooms in a randomized matched design. Collections were made in three houses per night on three consecutive nights, so that each house was sampled under each of the three treatments. This routine was repeated at 2-week intervals for 6 months. There was no significant difference between the overall numbers of sandflies collected in rooms with or without impregnated curtains. Only 0.14 sandflies/man-hour were caught on human bait under impregnated bednets, significantly fewer than the numbers collected on human bait outside the nets in the same room (1.91) or in unprotected rooms (3.29). In a second set of experiments carried out in La Guaira and the neighbouring community of Jiguales, the effect of deltamethrin impregnation was evaluated by comparing numbers of sandflies collected on human bait under treated and untreated nets. Significantly fewer were collected under the impregnated nets (0.25 v. 0.69/man-hour). Wild-caught female Lu.youngi exposed to treated netting for 2 min in the laboratory all died with 24 h. The impact of deltamethrin-impregnated bednets was considered to be useful against Lu.youngi and other potential vectors of leishmaniasis in such communities.

Animals↗
PubMed1996

Seasonal variation of Leishmania major infection rates in sandflies from rodent burrows in Isfahan province, Iran.

In preparation for field trials of killed Leishmania major vaccine, natural infections with Leishmania promastigotes were monitored in Phlebotomine sandfly vectors from villages of Borkhar rural district, northeast of Isfahan in central Iran, where L.major zymodeme MON-26 ( = LON-1) has been identified as causing zoonotic cutaneous leishmaniasis (ZCL). Sandflies were collected and dissected weekly, from burrows of rodent colonies, during the "sandfly season', June-October 1991. Leptomonad infection rates were 12% of 26 Phlebotomus ansarii, 8% of 280 P.caucasicus, 11% of 1042 P.papatasi and none of 126 Sergentomyia sintoni, being greatest during late August through September, coinciding with peak activity of the sandflies, 2-3 months before the highest incidence of ZCL human cases in November-December.

Animals↗
PubMed1995

Extreme fitness differences in mammalian and insect hosts after continuous replication of vesicular stomatitis virus in sandfly cells.

Continuous, persistent replication of a wild-type strain of vesicular stomatitis virus in cultured sandfly cells for 10 months profoundly decreased virus replicative fitness in mammalian cells and greatly increased fitness in sandfly cells. After persistent infection of sandfly cells, fitness was over 2,000,000-fold greater than that in mammalian cells, indicating extreme selective differences in the environmental conditions provided by insect and mammalian cells. The sandfly-adapted virus also showed extremely low fitness in mouse brain cells (comparable to that in mammalian cell cultures). It also showed an attenuated phenotype, requiring a nearly millionfold higher intracranial dose than that of its parent clone to kill mice. A single passage of this adapted virus in BHK-21 cells at 37 degrees C restored fitness to near neutrality and also restored mouse neurovirulence. These results clearly illustrate the enormous capacity of RNA viruses to adapt to changing selective environments.

Animals↗
PubMed2005

Relative abundances of sandfly species (Diptera: Phlebotominae) in two villages in the same area of Campeche, in southern Mexico.

Leishmania mexicana is the parasite causing most cases of human cutaneous leishmaniasis in southern Mexico, where Lutzomyia olmeca olmeca and Lu. cruciata are the most probable vectors. In the present study, sandflies were collected during one transmission season (November 2001-March 2002) in the village of La Guadalupe and the nearby village of Dos Naciones, in the southern Mexican county of Calakmul. Using Shannon traps, Disney traps and CDC light traps, 5983 sandflies (Brumptomyia and Lutzomyia) were caught. In Dos Naciones the numbers of Lu. panamensis caught in Shannon or CDC traps outnumbered those of the other sandfly species. In La Guadalupe, in contrast, the most abundant species in the collections made with Shannon or CDC traps was Lu. cruciata , followed by Lu. olmeca olmeca and Lu. deleoni. In both locations, the numbers of sandflies attracted to Shannon traps peaked between 18.00 and 22.00 hours. Given the abundance of Lu. olmeca olmeca in the collections made with Shannon and Disney traps (it was the only species caught in the latter), this species is probably the primary vector of Le. mexicana in Calakmul county.

Animals↗
PubMed2005

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.

Animals↗
PubMed2006

[Host feeding preferences of sandflies in rural area, Southern Brazil].

OBJECTIVE: To investigate the fauna and host feeding preferences of sandflies as for domestic animals in an endemic area of American cutaneous leishmaniasis. METHODS: The sandflies collections were carried out from 8:00 pm to 12:00 am in an area 40 meters away from one of the residences in a farm in Southern Brazil, between January and April, 2004. Collection was performed using four Falcão light traps, placed 5 m apart from each other beside a cage, each one of them containing an animal bait (swine, dog, rabbit, and chicken). RESULTS: A total of 1,697 specimens of sandflies were collected as follows: Nyssomyia whitmani, Pintomyia fischeri, Migonemyia migonei, Nyssomyia neivai, Pintomyia pessoai and Psathromyia shannoni. The prevalent species was N. whitmani. There were no feeding preferences of sandflies as for the animals studied. CONCLUSIONS: N. whitmani and P. fischeri are opportunistic species and female insects probably adjust their eating habits to host availability, suggesting eating eclecticism of these insects in anthropic environments.

Analysis of Variance↗
PubMedDate not supplied

Distribution of sandflies (Diptera:Psychodidae) on tree-trunks in a non-flooded area of the Ducke Forest Reserve, Manaus, AM, Brazil.

Sandflies were collected in the base of tree-trunks in the seasons of high and least rainfall in the Ducke Forest Reserve, near Manaus in the State of Amazonas. Lutzomyia umbratilis was the most abundant sandfly species. Caryocar villosum, Chrysophyllum amazonicum, Dinizia excelsa, Eschweilera atropetiolata and Parkia multijuga were the tree species on which most sandflies were collected and relative abundance were related to trunk characteristics. Seasonal patterns of sandfly distribution in the forest were observed.

Animals↗
PubMed2006

Sandfly fauna in a military training area endemic for American tegumentary leishmaniasis in the Atlantic Rain Forest region of Pernambuco, Brazil.

The aim of this study was to characterize the sandfly fauna in a military training area situated in the "Zona da Mata" region of Pernambuco State, Brazil, where human cases of American tegumentary leishmaniasis (ATL) had been observed, caused by Leishmania (Viannia) braziliensis. The occurrence of 16 sandfly species in the Marshall Newton Cavalcanti Military Training Camp (CIMNC) indicates an important diversity of sandfly species in this study area. Lutzomyia complexa was the most common species (51.36%) followed by L. choti (43.54%). All the captures were made in areas where training activities were conducted and where clinical cases had been detected in individuals performing training, following this period. The data relating the sandfly behavior to previous data in the same area provides strong evidence for the occurrence of an enzootic cycle of the parasite, and outbreaks followed the period of training activities in the remaining Atlantic Rain Forest and secondary forest areas.

Animals↗
PubMed1999

Sandflies (Diptera: Psychodidae) associated with epidemic cutaneous leishmaniasis in Sanliurfa, Turkey.

As part of a project to study the possible impact of environmental change on health in southeastern Turkey, we evaluated sandfly species diversity, abundance, and habitat associations in an urban area where cutaneous leishmaniasis was undergoing epidemic re-emergence. Houses and caves in and around the city of Sanliurfa, Turkey, were sampled using mechanical aspirators, sticky papers, and CDC light traps. Of 1,649 sandflies captured, including 6 Phlebotomus and 1 Sergentomyia species, nearly all were P. papatasi (Scopoli) (967) or P. sergenti Parrot (674). Sandflies were active during June-September (hot dry season), but not during January (cool rainy season). Resting phlebotomines were abundant inside houses. Houses sampled in 3 neighborhoods with a high cutaneous leishmaniasis incidence (9-65 cases per 1,000 population) had > 10 times more flies than at a comparison site where few cases (0.2 per 1,000) have been reported. Results indicated that P. sergenti or P. papatasi were the probable vectors of cutaneous leishmaniasis during this outbreak and that control of these sandflies may eliminate transmission.

Animals↗
PubMedDate not supplied

[Comparative assessment of several methods of calculating the number of sandflies in the open air (Psychodidae)].

In summer of 1973-1974 a comparative counting of the number of sandflies was carried out by two methods in the Turkmenian Soviet Socialist Republic. Sheets of oil paper fastened vertically to two wires at a height of 60 cm above the ground at a distance of 20 cm one from another (barriers) and sheets in the form of "flags" (Dergachova and others, 1973) were used simultaneously. 15860 sandflies (X on one sheet 31.2+/-3.2 specimens) were collected on 50 barriers consisting of 10 sheets each; and on 500 flags 7640 sandflies (X on one flag 15.3+/-1.37 specimens) were collected. When sandflies are caught on flags the coefficient of counting equal to 2.1+/-0.37 should be taken.

Animals↗