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Complement-mediated lysis and infectivity for mouse macrophages and sandflies of virulent and attenuated Leishmania major promastigotes varying in expression of the major surface protease and lipophosphoglycan.

The infectivity to mouse macrophages and sandflies, the expression and enzymatic activity of the major surface glycoprotein (gp63), the developmental modification of lipophosphoglycan (LPG) and three metacyclogenesis markers (promastigote body size, lectin agglutination and complement resistance) were compared in four related Leishmania major promastigote lines. The lines, which differed in their virulence for BALB/c mice, were examined in both logarithmic and stationary phase. Although the two non-virulent lines were unable to survive and multiply within the macrophages, they were better at attaching to the macrophages and infecting sandflies than the two virulent lines, which were highly infective for macrophages. Except for the higher resistance of the attenuated parasites to complement-mediated lysis, there were no clear differences between the metacyclogenesis markers of the four lines. The amount and enzymatic activity of surface gp63 was relatively high in the attenuated promastigotes and this appears to be related to a higher expression of gp63 genes. In terms of LPG, cells of all the lines had approximately twice the number of galactose and mannose residues per molecule when in logarithmic phase than when in stationary phase. LPG of the virulent lines also contained approximately twice the mannose and galactose residues of the attenuated line. Although L. major gp63 could therefore be important for promastigote survival in the sandfly and for the resistance to complement-mediated lysis, there was no apparent correlation between gp63 expression and promastigote survival in the macrophage. A very elongated LPG could be necessary for the survival and proliferation of the parasite in macrophages.

Animals↗

Leishmania major: effect of repeated passages through sandfly vectors or murine hosts.

Virulence for BALB/c mice, infectivity for Phlebotomus papatasi, haemagglutination activity and expression of metacyclic lipophosphoglycan (LPG) were studied in four strains of Leishmania major (LV561, FV1, L119 and Neal) and various lines of the LV561 strain. Attenuated line LV561/AV was passaged five times through sandflies or mice and the resulting lines (AVS5 and AVM5, respectively) and two of the earlier sandfly passages (AVS1 and AVS2) were used for further study. The highly virulent line LV561/V served as a control. Virulence for mice was not regained during passaging of LV561/AV in sandflies or mice (none of the mice infected with AVM5, AVS1, AVS2 or AVS5 displayed overt lesions) and the success rate in cultivating parasites, from lymph-node samples from inoculated mice, was not significantly higher for any of these lines than for the original line (LV561/AV). However, AVM5 and AVS5 developed better than LV561/AV in P. papatasi and the intensity and localisation of their infections were similar to those of the virulent control. In smears of the infected guts of P. papatasi, the AVS5 parasites resembled the virulent line (LV561/V) morphologically whereas the AVM5 parasites were similar to the avirulent LV561/AV. Haemagglutination activity increased as a result of passaging, the most pronounced difference being observed in AVM5, which had 60-fold higher activity than LV561/AV. Expression of metacyclic LPG was not increased by passaging. The proportion of forms reacting positively with 3F12 antibodies was high (about 17%) in the virulent LV561/V but low (2%-3%) in the avirulent lines LV561/AV, AVS5 and AVM5. A defect in LPG is not, however, likely to be the only reason for the avirulence observed, as the avirulent lines of LV561 still produced about 10 times as many metacyclic promastigotes as the strain L119, which caused delayed lesions in mice.

Animals↗

Preliminary account of the phenology of some Nigerian savanna phlebotomine sandflies (Diptera: Psychodidae).

A total of 1,705 sandflies was collected by sticky trap from the Guinea savanna of northern Nigeria to determine their seasonal and spatial fluctuations in abundance. Adult sandflies persisted throughout the year, but the highest diversity and abundance were recorded at the end of the rainy season. Females were collected more frequently than were males. The species collected in order of decreasing abundance were Sergentomyia antennata Newstead, S. bedfordi Newstead, S. africana Newstead, S. schwetzi Adler, Theodor & Parrot, S. affinis Theodor, S. adleri Theodor, S. clydei Sinton, S. simillima Newstead, S. buxtoni Theodor, S. christophersi Sinton, and Phlebotomus rodhaini Parrot. Sandfly abundance was greater near rocky terrain (Dumbi inselberg) and on an animal farm than on the open plains and in a residential area. Known vectors of leishmaniasis were not collected, despite the report of human cases in the study area.

Animals↗

Leishmaniasis in Sardinia. III. Soil analysis of a breeding site of three species of sandflies.

Soil analysis was carried out on samples obtained from a breeding-site of the sandflies Phlebotomus perniciosus Newstead, P. perfiliewi perfiliewi Parrot and Sergentomyia minuta (Rondani) in Sardinia. Soil texture, pH, CaCo3, organic matter and water content showed no correlation with the number of sandflies that emerged from the places where soil samples were taken. It appears that pre-imaginal stages of these phlebotomine sandflies are associated with a relatively stable, cool and humid environment protected from sunshine and rain, rich in clay and in organic nitrogen.

Animals↗

Aspects of sandfly biology in southern Switzerland.

During three field surveys of phlebotomine sandflies in the region of Sessa, Minor Malcantone, southern Switzerland, annually 1987-89, Phlebotomus perniciosus and P. mascittii were caught regularly by means of light traps, but only when the traps were in close association with humans. The most productive catching sites were in the middle of Sessa village, in basements or partially closed shelters in the immediate vicinity of human dwellings. All catching sites outside the village were negative. The only other sandfly species caught was Sergentomyia minuta, four specimens only. P.perniciosus and P.mascittii always occurred together and were found to feed--at least occasionally--on human blood. Glucose and fructose were identified in wild-caught sandflies of both species. A breeding place of P. mascittii was identified in the basement of a house in the middle of Sessa. Analyses of soil samples revealed moderately loamy humus with a slightly acidic pH (5.6).

Animals↗

Arabian sandflies (Diptera: Psychodidae) prefer the hottest nights?

A vehicle-mounted net was used to collect hourly samples of sandflies on 15 nights during June in northern Oman. Every half hour, the temperature, relative humidity, wind velocity and light intensity were measured (there was no cloud or rainfall during this period). The sandflies caught were mainly Phlebotomus alexandri and Sergentomyia clydei. Their circadian activity increased rapidly after sunset (18.50 hours). The high level of activity was fairly constant during 9h of darkness until dawn, when it decreased rapidly. A few flies were still active at 07.00 hours, 1.5h after sunrise. A multiple regression showed that the main factor affecting sandfly activity was light intensity. When this factor was removed, by considering only the 135 catches collected during the 9h of darkness, the second most important factor was low relative humidity, followed by low wind velocity. Temperature was not a significant factor in the analysis, because of its strong negative correlation with humidity. However, when the effect of humidity was removed from the regression, high temperature became significant, but less important than wind. The regressions showed that, for flight activity, the optimum humidity was around 10%; the probable maximum wind velocity was 3.5 m s-1 and 11 degrees C was the probable minimum temperature. Thus, when the 4 nights with highest catches (200-260 flies/night) were compared with the 4 nights with lowest catches (50-120 flies/night), the best nights had a low humidity (10-25%) and low wind speed (< 0.3 m s-1) in combination with highest temperatures (31-43 degrees C).

Animals↗

Phlebotomine sandflies associated with a focus of cutaneous leishmaniasis in Valle del Cauca, Colombia.

A survey was made of the phlebotomine sandfly fauna of La Guaira, a village with coffee plantations near Cali, Colombia, from which cases of American cutaneous leishmaniasis had been reported due to Leishmania (Viannia) panamensis and Le. (V.) braziliensis. Among six species of sandfly collected on human bait, Lutzomyia youngi was most important in terms of biting nuisance. Lu.columbiana, Lu.lichyi and Lu.scorzai as well as Lu.youngi adults occurred throughout the year. Sandfly man-biting activity occurred throughout the night and was highest within 2 h of sunset. Despite its abundance in nocturnal samples, Lu.youngi was rarely taken in diurnal resting site collections. In contrast, Lu.lichyi was collected on tree-trunks during the day in large numbers and was the only species biting in daylight. The implications of these and other findings for leishmaniasis control measures in La Guaira are considered.

Animals↗

Chorion patterns on eggs of Lutzomyia sandflies from the Peruvian Andes.

Scanning electron microscopy (SEM) as used to depict and describe the eggs of five species of phlebotomine sandfly from the Andean region of Peru: Lutzomyia caballeroi, Lu.noguchii, Lu.peruensis, Lu.tejadai and Lu.verrucarum. Two new types of chorionic sculpturing of sandfly eggs are reported: these were named disperse (Lu.tejadai) and verrucose (Lu.noguchii). The aeropylar area of the eggs is also described for the first time for neotropical sandflies. These character states appear to vary for ecological rather than phylogenetic reasons and could be used for species identification.

Animals↗

The sandfly fauna in the visceral-leishmaniasis focus of Gedaref, in the Atbara-River area of eastern Sudan.

Visceral leishmaniasis (VL) is an acute public-health problem in Sudan. Between 1997 and 2000, four, brief entomological surveys were carried out in Barbar El Fugarra, a village in the state of Gedaref, in the Atbara-River area of eastern Sudan. Between 1996 and 1999, 658 cases of VL occurred among the village's population of about 4000. CDC miniature light-traps set inside and outside human dwellings were used to collect a total of 12,745 sandflies, including five species of the genus Phlebotomus and 19 of Sergentomyia. Phlebotomus papatasi and P. orientalis made up 7% and 5% of the collected sandflies, respectively. Seasonal variation was observed in the numbers of P. orientalis, P. papatasi, S. schwetzi and S. magna caught. Almost all (88%) of the sandflies collected were caught inside houses or granaries and there appeared to be particularly large indoor populations of P. orientalis, P. papatasi, S. schwetzi, S. magna and S. clydei. Phlebotomus orientalis could be responsible for the indoor transmission of the parasites causing the local VL, between humans and between humans and local dogs (which have been found infected by some of the Leishmania zymodemes found in humans). The co-occurrence in this focus of P. papatasi and Arvicanthis niloticus, which are known vectors and reservoir hosts, respectively, of L. major, indicates the possibility that outbreaks of human cutaneous leishmaniasis might occur in the area.

Animals↗

Wolbachia infection and the expression of cytoplasmic incompatibility in sandflies (Diptera: Psychodidae) from Egypt.

A PCR-based method was used to screen four laboratory colonies of sandflies for Wolbachia infection. The colonies - one of Phlebotomus langeroni, one of P. bergeroti and two of P. papatasi - were all derived from sandflies collected in Egypt. Only one of the colonies, derived from P. papatasi collected in Sinai, was found infected. The sequence of the PCR product for this colony was identical to that previously reported for the Wolbachia in P. papatasi from Israel. The induction with tetracycline of cytoplasmic incompatibility (CI) in flies from the P. papatasi (Sinai) colony was then investigated, through reciprocal crosses between treated and untreated P. papatasi siblings. Partial CI expression was attained in the crosses involving antibiotic-treated (i.e. uninfected) females, whether the males used were infected with Wolbachia or had also been cleared of Wolbachia by antibiotic treatment. Most (75%) of the eggs oviposited by uninfected females that had been crossed with infected males, and most (58%) of those laid by uninfected females that had been crossed with uninfected males, failed to hatch. These results provide the first published evidence showing that Wolbachia infection in sandflies is advantageous to the insects. The failure to detect Wolbachia in one of the colonies derived from Egyptian P. papatasi or in the colonies derived from Egyptian P. bergeroti and P. langeroni may indicate that the inter- and intra-specific spread of Wolbachia is discontinuous, even within one country.

Animals↗

The sandflies (Diptera: Psychodidae) in the Turkish province of Hatay: some possible vectors of the parasites causing human cutaneous leishmaniasis.

The province of Hatay, which lies on the Mediterranean coast in south-eastern Turkey, forms an important endemic area for human cutaneous leishmaniasis (HCL). Between the June and November of 2001, the sandflies in eight areas of the province, Erzin, Dortyol, Iskenderun, Kirikhan, Antakya, Samandag, Altinozu and Yayladagi, were surveyed, using sticky-paper traps placed in goat, sheep, cow or chicken sheds close to houses. Although 217 of the 998 sandflies caught belonged to the genus Sergentomyia, the rest were of Phlebotomus species, including some species that, elsewhere, are known to act as vectors of the parasites causing HCL. The Sergentomyia caught were either S. theodori (59.9%) or S. dentata (40.1%). Most of the Phlebotomus were P. sergenti (60.8%) but P. papatasi (18.8%), P. syriacus (9.3%), P. neglectus (5.1%), P. tobbi (2.7%), P. simici (2.2%), P. alexandri (0.9%) and P. kyreniae (0.1%) were also identified (the latter three species for the first time in Hatay province). The identification of the main vector species of sandfly in the province is complicated because it is still uncertain which Leishmania species cause(s) the local HCL. It seems likely, however, that P. sergenti is the main vector in Antakya, Iskenderun, Dortyol, Erzin and Kirikhan. In areas such as Altinozu and Yayladagi, where, although P. sergenti is very rare or absent, HCL cases still occur each year, other species, such as the relatively abundant P. papatasi and P. syriacus, may be the main vectors.

Animals↗

An inventory of the phlebotomine sandflies (Diptera: Psychodidae) found in the Turkish province of Konya.

Between the April and October of 1997, the sandflies in six areas (Centrum, Altinekin, Kadinhani, Cumra, Beysehir and Bozkir) of the Turkish province of Konya, in Central Anatolia, were surveyed. All the sandflies were caught close to houses, on sticky-paper traps placed in barns used by livestock. All 127 specimens of Sergentomyia collected were either S. theodori (86.6%) or S. dentata (13.4%). The other 2017 sandflies caught represented 12 species of Phlebotomus - mostly P. papatasi (78.4%) or P. halepensis (10.9%), with P. sergenti (3.8%), P. simici (2.2%), P. kandelakii (1.6%), P. similis (0.9%), P. jacusieli (0.5%), P. neglectus (0.4%), P. transcaucasicus (0.3%), P. syriacus (0.3%), P. kyreniae (0.3%) and P. balcanicus (0.3%) relatively rare. Most (87%) of the flies were male. This represents the first report of P. transcaucasicus in Turkey. In addition, P. syriacus, P. neglectus, P. similis and S. dentata have not been detected before in Central Anatolia.

Animals↗

High degree of conservancy among secreted salivary gland proteins from two geographically distant Phlebotomus duboscqi sandflies populations (Mali and Kenya).

BACKGROUND: Salivary proteins from sandflies are potential targets for exploitation as vaccines to control Leishmania infection; in this work we tested the hypothesis that salivary proteins from geographically distant Phlebotomus duboscqi sandfly populations are highly divergent due to the pressure exerted by the host immune response. Salivary gland cDNA libraries were prepared from wild-caught P. duboscqi from Mali and recently colonised flies of the same species from Kenya. RESULTS: Transcriptome and proteome analysis resulted in the identification of the most abundant salivary gland-secreted proteins. Orthologues of these salivary proteins were identified by phylogenetic tree analysis. Moreover, comparative analysis between the orthologues of these two different populations resulted in a high level of protein identity, including the predicted MHC class II T-cell epitopes from all these salivary proteins. CONCLUSION: These data refute the hypothesis that salivary proteins from geographically distinct populations of the same Phlebotomus sandfly species are highly divergent. They also suggest the potential for using the same species-specific components in a potential vector saliva-based vaccine.

Africa, Eastern↗

[Phlebotomine sandflies of Southern Brazil].

OBJECTIVE: To identify the sandfly fauna and some aspects of their behavior in forest and anthropic environments. METHODS: Sandfly captures were undertaken in farm (23 degrees 6' S; 50 degrees 22' W), in Southern Brazil. Falcão light traps were set in forest, domicile and domestic animal shelters and mosquitoes were collected monthly, between 17h and 7h, from March 1997 to February 1998. RESULTS: A total of 3,655 specimens representing 13 species were captured. Nyssomyia whitmani and Nyssomyia neivai were the predominant species, with a total of 2,977 specimens (81.0%). Of these two species, a total of 2,552 (85.7%) specimens were captured in intradomiciliary and peridomiciliary environments, 2,332 (91.3%) of them in a pigsty. These two species predominated between 20h-21h when 90.4% of the specimens were captured. CONCLUSIONS: Five sandfly species, N. whitmani, N. neivai, Migonemyia migonei, Pintomyia pessoai and Pintomyia fischeri, potential vectors of cutaneous leishmaniasis, were captured. The importance of the two former species is emphasized, since both presented similar behavior in regard to seasonal period, hourly frequency and predominance in the anthropic environment. Besides, N. whitmani was the most predominant species.

Animals↗

Ecology of sandflies (Diptera: Psychodidae) in a restricted focus of cutaneous leishmaniasis in northern Venezuela. I. Description of the study area, catching methods and species composition.

A study on the ecology of phlebotomine sandfly fauna in a restricted focus of cutaneous leishmaniasis in northern Venezuela was undertaken in order to investigate the species responsible for the transmission. The study area and catching methods for phlebotomine sandflies are described. A total of 9,061 females and 1,662 males were collected during a year-term study. 12 species of Lutzomya and 1 species of Brumptomya sp. were identified. Absolute and relative abundance and occurrence for each species were determined. The relative occurrence allowed to distinguish the common species, viz. L. panamensis, L. ovallesi, L. gomezi, L. trinidadensis, L. atroclavata, L. cayennensis, L. shannoni and L. olmeca bicolor from the rare species vis., L. punctigeniculata, L. rangeliana, L. evansi and L. dubitans. General comments on the species composition of the sandfly fauna in this locality are made.

Animals↗

Effect of deltamethrin spraying on the sandfly populations in a focus of American cutaneous leishmaniasis.

The effect of deltamethrin of the sandfly population in a focus of American Cutaneous Leishmaniasis in Viana, Espírito Santo State is described. The phlebotomine population density was determined inside and outside houses during a one year period in a treated and untreated area. The results showed a significant reduction in the number of sandflies inside houses in the treated area compared with both the untreated area and the same area before spraying. Despite having a residual action for 12 months after spraying the insecticide was ineffective outside houses. It is concluded therefore that deltamethrin is an efficient insecticide for reducing the number of phlebotomine sandflies inside houses.

Animals↗

[Sandflies (Diptera, psychodidae) in a secondary forest area in the Paco do Lumiar city, Maranhao, Brazil: a leishmaniasis transmission area].

This paper analyzes the wealth of species, relative abundance, seasonal fluctuation, and nocturnal activity of sandflies. The field survey was conducted in a "capoeira" (secondary forest) area in the county of Paço do Lumiar, Maranhão, where cutaneous and transmission of visceral leishmaniasis frequently occurs. Sandflies were captured by CDC-type light traps from 6:00 PM to 6:00 AM, once a month, from March 1997 to February 1998. A total of 489 specimens were collected (251 males and 238 females), distributed among 10 species: Lutzomyia antunesi (45.19%), Lutzomyia whitmani (29.4%), Lutzomyia longipalpis (7.56%), Lutzomyia sordelli (6.34%), Lutzomyia flaviscutellata (4.5%), Brumptomyia avellari (4.09%), Lutzomyia evandroi (1.85%), Lutzomyia umbratilis (0.61%), Lutzomyia corossoniensis (0.41%), and Lutzomyia trispinosa (0.41%). The sandflies were present year round, with higher abundance during the rainy season. They were present in all intervals studied, with the highest frequency between 12:00 PM and 1:00 AM (31%).

Animals↗

Sandfly maxadilan exacerbates infection with Leishmania major and vaccinating against it protects against L. major infection.

Bloodfeeding arthropods transmit many of the world's most serious infectious diseases. Leishmania are transmitted to their mammalian hosts when an infected sandfly probes in the skin for a bloodmeal and injects the parasite mixed with its saliva. Arthropod saliva contains molecules that affect blood flow and modulate the immune response of the host. Indeed, sandfly saliva markedly enhances the infectivity of L. major for its host. If the salivary molecule(s) responsible for this phenomenon was identified, it might be possible to vaccinate the host against this molecule and thereby protect the host against infection with Leishmania. Such an approach represents a novel means of controlling arthropod-borne disease transmission. Here, we report that a single molecule, maxadilan, in sandfly saliva can exacerbate infection with L. major to the same degree as whole saliva, and that vaccinating against maxadilan protects mice against infection with L. major.

Animals↗