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PubMed1997

Vector-host-parasite inter-relationships in leishmaniasis. III. Impact of blood meal from natural vertebrate hosts on the survival and the development of Leishmania infantum and L. major in Phlebotomus langeroni (Diptera: Psychodidae).

Phlebotomus langeroni collected from a leishmaniasis endemic focus at Et Agamy, Alexandria, Egypt, were found to have fed on blood from man, dogs (Canis familiaris) and rats (Rattus rattus). The effect of the kind of blood meal on the development and the life-cycle of L. infantum and L. major in laboratory reared P. langeroni was therefore investigated. A membrane feeding technique was used to infect sand flies. Gut smears of infected females were examined immediately after feeding and daily for 16 days. Nectomonads and short promastigote forms of L. infantum or L. major were detected in females fed on human, dog and rat bloods at all intervals. Paramastigotes (infective stage) were present only in females fed on dog blood containing L. infantum or L. major and in those fed on rat blood containing L. major. It is concluded that among the factors influencing the Leishmania-phlebotomus relationship is the natural medium in which the parasite is present in vivo. The blood of the natural reservoir host(s) is the key factor for the development of the infective parasite form in the sand fly and P. langeroni could be considered a potential vector for transmitting L. infantum from dogs and L. major from rats and dogs but not from man. This investigation offers a new concept for the study of interactions among vector, host and parasites in Leishmania transmission.

Animals↗
PubMed1993

Phlebotomine sandflies of Kenya (Diptera: Psychodidae). I. The validity of Phlebotomus (Larroussius) elgonensis Ngoka, Madel and Mutinga.

Sandflies collected in Kitum cave on the Kenyan side of Mount Elgon were identified as Phlebotomus (Larroussius) elgonensis Ngoka, Madel and Mutinga, a species synonymized with P. (L.) aculeatus Lewis, Minter and Ashford, by D. J. Lewis. A comparison of the flies from Kitum cave with P. aculeatus from Lake Elmentaita, Kenya, shows marked differences in the lengths of: (a) the spermathecal ducts of the female; (b) the style, coxite, genital pump and aedeagus of the male; and (c) the palpal segments of both sexes. Other notable differences are in the shape of the base of the spermathecal ducts; the position of spines on, and the shape of, the tip of the aedeagus; and the appearance of the pharyngeal armatures of both sexes. Phlebotomus elgonensis is redescribed and it is concluded that it is sufficiently different from P. aculeatus to deserve recognition as a valid species.

Animals↗
PubMed2000

[The subgenus Paraphlebotomus (Phlebotomus--Phlebotominae-- Psychodidae--Diptera): a review. Morphological and molecular studies].

A systematic review of the subgenus Paraphlebotomus (a group of phlebotomine sandflies which contains several vectors of leishmaniasis) is proposed. In the morphological approach, we study the available types and a lot of sandflies coming from different geographic areas. The taxonomic status of each species is revised. We consider P. marismortui as a synonym of P. alexandri. We suppose that P. mofidii is a valid species. P. similis is clearly differentiated from P. sergenti. A new species is described from North Africa: P. riouxi. We discuss the validity of P. saevus. Two molecular phylogenies based on ribosomal DNA sequences are proposed. The first one used the D2 domain of the 28 S sub-unit. It emphasises a very close relation between the subgenera Paraphlebotomus and Phlebotomus, a likely paraphyly of the genus Phlebotomus and the position of the genera Sergentomyia and Lutzomyia as two sister groups. The second one used the ITS 2. It emphasises the informative capacity of this gene for the resolution of the phylogenetic relations within the subgenera Paraphlebotomus.

Animals↗
PubMed1996

The potential effect of global warming on the geographic and seasonal distribution of Phlebotomus papatasi in southwest Asia.

The distribution of Phlebotomus papatasi in Southwest Asia is thought to be highly dependent on temperature and relative humidity. A discriminant analysis model based on weather data and reported vector surveys was developed to predict the seasonal and geographic distribution of P. papatasi in this region. To simulate global warming, temperature values for 115 weather stations were increased by 1 degree C, 3 degrees C, and 5 degrees C, and the outcome variable coded as unknown in the model. Probability of occurrence values were then predicted for each location with a weather station. Stations with positive probability of occurrence values for May, June, July, and August were considered locations where two or more life cycles of P. papatasi could occur and which could support endemic transmission of leishmaniasis and sandfly fever. Among 115 weather stations, 71 (62%) would be considered endemic with current temperature conditions; 14 (12%) additional stations could become endemic with an increase of 1 degree C; 17 (15%) more with a 3 degrees C increase; and 12 (10%) more (all but one station) with a 5 degrees C increase. In addition to increased geographic distribution, seasonality of disease transmission could be extended throughout 12 months of the year in 7 (6%) locations with at least a 3 degrees C rise in temperature and in 29 (25%) locations with a 5 degrees C rise.

Animals↗
PubMed1977

Studies on the epidemiology of sandfly fever in Iran. I. Virus isolates obtained from Phlebotomus.

A total of 62 virus isolates was obtained from 12,485 male and female sandflies (predominately Phlebotomus papatasi) collected in a village in central Iran during the summer of 1975. The overall virus isolation rate from female sandflies was 1 per 177 insects processed. Of the 62 virus strains obtained, 49 were identified as Sicilian virus, 11 as Karimabad, and 2 as a new member of the vesicular stomatitis serogroup. One isolate each of Sicilian and Karimabad virus was made from pools of male sandflies. The three virus types were active in the sandfly population simultaneously. Sicilian virus isolation rates showed little variation during the study period, suggesting continuous virus activity during the sandfly season. The implications of these findings for the epidemiology of sandfly fever are discussed.

Animals↗
PubMed1977

Studies on the epidemiology of sandfly fever in Iran. III. Host-feeding patterns of Phlebotomus papatasi in an endemic area of the disease.

Blood meals from 575 Phlebotomus papatasi collected in an Iranian village were identified by precipitin test. The majority of sandfly feedings (57.5%) were on birds, mainly chickens and pigeons. The remaining 42.5% were on mammals (humans, cows, mules, sheep, and goats) or were non-reactive. Calculation of forage ratios of each host species indicated that chickens, equines, and bovines were the preferred hosts of P. papatasi in the village. Results of this study demonstrate that P. papatasi has a much wider natural host range than indicated previously and suggest that this species is an opporunistic feeder and is not strongly anthropophilic. Observations on the diurnal activity of P. papatasi are also presented.

Animals↗
PubMed1988

Experimental infection of Phlebotomus papatasi with sand fly fever Sicilian virus.

Experimental studies were conducted to evaluate humans as hosts infecting the sand fly Phlebotomus papatasi with sand fly fever Sicilian (SFS) virus. Viral antigen and infectious virus circulated in the blood of infected volunteers on days 4 and 5 after intravenous inoculation with SFS virus. Viremia levels during the latter period were high enough to infect feeding sand flies, but only 13% (9/69) of the flies became infected. One out of every 3 infected sand flies that survived to feed a second time transmitted SFS to a hamster. These results confirm a vertebrate-sand fly-vertebrate transmission cycle for SFS virus, and demonstrate that horizontal transmission may contribute to the maintenance of this virus in nature.

Animals↗
PubMed1984

Antigenic and biological characterization of Toscana virus, a new Phlebotomus fever group virus isolated in Italy.

Toscana (TOS) virus, a new member of the Phlebotomus fever serogroup of arboviruses, was isolated from sandflies collected in Italy. It was shown to be closely related to Sandfly fever Naples (SFN) virus. The antigenic relationships between the two viruses were analysed in the complement fixation (CF), plaque reduction neutralization (PRN) and indirect fluorescent antibody (IFA) tests. TOS virus multiplied to high titres with a cytopathic effect (CPE) in several vertebrate cell cultures (e.g. Vero, BHK-21, etc.), whereas it failed to replicate in mosquito cell cultures. Plaque formation by TOS virus in Vero cells was not affected by incorporating dimethyl sulphoxide in the overlay, which is known to enhance plaque formation by SFN virus. Some biological characteristics in cell cultures and in mice of a mouse-adapted and a cell-adapted TOS virus strain were studied. After 4-6 passages in the two different systems, changes in plaque size, in the amount of autointerfering activity and of virulence for mice were observed.

Animals↗
PubMed1986

Scanning electron microscopy of Leishmania major in Phlebotomus papatasi.

The morphology of Leishmania major parasites and their interactions with various regions of the alimentary canal of Phlebotomus papatasi were studied by scanning electron microscopy. Parasites were observed to undergo development initiated with the ingestion of amastigotes and culminating in a characteristic distribution of four distinct morphological forms in various parts of the alimentary canal: namely, large numbers of elongate nectomonads in the abdominal mid-gut, haptomonad forms attached to the cuticle of the stomodeal valve, small spherical forms attached to the esophagus and masses of short promastigotes, believed to be the infective forms, lying free in the anterior thoracic mid-gut and the esophagus.

Animals↗
PubMed1993

Influence of Leishmania infection on blood-meal digestion in the sandflies Phlebotomus papatasi and P. langeroni.

The presence of amastigote-initiated infections of Leishmania major parasites caused a significant suppression in alkaline protease, trypsin and aminopeptidase activity during the first 30 h after ingestion of the infected bloodmeal in Phlebotomus papatasi, the natural vector of L. major. Protease levels were significantly higher in infected flies after 72 h than in the control group, where digestion had ceased. Evidence for the suppression of protease activity in infected P. langeroni, a sympatric but un-natural vector of L. major, was less clear; there was no difference in alkaline protease activity between control and infected groups in the first 24 h. However, protease, trypsin and aminopeptidase activities were elevated after 72 h in infected P. langeroni, indicating a delay in the time to the end of digestion and passage of the bloodmeal. The potential advantages for parasite development in suppressing protease activity and extending the period of bloodmeal digestion are discussed.

Aminopeptidases↗
PubMed2005

Structure and function of the spermathecal complex in the phlebotomine sandfly Phlebotomus papatasi Scopoli (Diptera: Psychodidae): I. ultrastructure and histology.

Females of phlebotomine sandflies (Diptera: Psychodidae) possess highly variable spermathecae that present several important taxonomic characters. The cause of this diversity remains a neglected field of sandfly biology, but may possibly be due to female post-mating sexual selection. To understand this diversity, a detailed study of the structure and function of the spermathecal complex in at least one of the species was a prerequisite. Using scanning and transmission electron microscopy, described here is ultrastructure of the spermathecal complex in the sand fly, Phlebotomus papatasi Scopoli. The spermathecal complexes are paired; each consists of a long spermathecal duct, a cylindrical spermathecal body, and a spherical spermathecal gland. Muscle fibres, nerves, tracheoles, and vascular sinuses connect the spermathecal body and duct through the epithelial layers. Spermathecal gland is formed by a typical insect epidermis and consisting of an epithelial layer of class-1 epidermal cells and elaborate glandular cells of class-3 epidermal cells, each having both receiving and conducting ductules (i.e. "end apparatus") and a "cytological apodeme", which is a newly described cell structure. The spermathecal body and duct are lined by class-1 epidermal cells and a cuticle, and are enveloped by a super-contracting visceral muscular system. The cuticle consists of rubber-like resilin, and its fibrillar arrangement and chemical nature are described. A well-developed neuromuscular junction exists between the spermathecal gland and the spermathecal body, which are connected to each other by a nerve and a muscle. The spermathecal complexes of the sandfly are compared with those of other insect species. The physiological role and possible evolutionary significance of the different parts of spermathecal complex in the sandfly are inferred from the morphology and behaviour. Post-mating sexual selection may be responsible for the structural uniqueness of the spermathecal complex in phlebotomine sandflies.

Animal Structures↗
PubMed2005

Structure and function of the spermathecal complex in the phlebotomine sandfly Phlebotomus papatasi Scopoli (Diptera: Psychodidae): II. post-copulatory histophysiological changes during the gonotrophic cycle.

The spermathecal complex of Phlebotomus papatasi Scopoli (Diptera: Psychodidae) undergoes histological and physiological changes during its gonotropic cycle. The present histochemical study revealed a mucopolysaccharide secretory mass in the spermathecae of the newly emerged sandfly. Sperm competition occurs when two or more males compete to fertilize an ovum in the female reproductive tract. In this study, spermatophores of two or more competing males were deposited at the base of the spermathecal ducts, which originate from the female bursa copulatrix. This suggests that females play a role in sperm displacement, which is defined as any situation in which the last male to mate with a female fertilizes maximum number her eggs. A blood meal ingested by the female for ovary development and egg laying stimulates the release of sperm from the spermatophore. The spermatozoa then migrate to the lumen of the spermatheca. The ultrastructure of spermatozoa comprises a head with double-layered acrosomal perforatorium, an elongate nucleus, and the axoneme with a 9 + 9 + 0 flagellar pattern. This axomene differs from the flagellate axoneme of other Psychodinae. Morphological changes, such as the casting off of the acrosomal membrane, and histological changes in the spermatophore are also described. Mating plugs that have been described previously in sandflies appear to be artefacts. Females of P. papatasi may be inseminated more than once during each gonotrophic cycle, and additional inseminations may be necessary for each cycle. The relationships between the volumes of the sperm and the spermatheca were calculated to determine sperm utilization and fecundity of P. papatasi. As the females of P. papatasi mate polyandrously, the anatomical and physiological complexity of the spermathecal complex may be related to post-copulatory sexual selection.

Animal Structures↗
PubMed2007

The establishment, maintenance and productivity of a laboratory colony of Phlebotomus similis Perfiliew, 1963 (Diptera, Psychodidae).

Phlebotomus similis is a relatively poorly understood sand fly species. This paper presents the results of the first successful laboratory colonization of P. similis. Some bionomic factors collected on the life history, behaviour, feeding preferences, and characteristics of developmental biology of this species are described. Furthermore, the parameters of the dynamics and the life history of this species under laboratory conditions were quantified. These results will facilitate further studies necessary for understanding its potential role as a vector of leishmaniasis in the Mediterranean.

Animals↗
PubMed1996

Phlebotomus sergenti parrot, 1917: morphological and isoenzymatic comparisons of two natural populations from Tenerife (Canary Islands, Spain) and Crete (Greece).

Samples of two Phlebotomus sergenti natural populations from San Juan (Tenerife), representing the western edge of the distribution area of this species, and Axos (Crete) were collected. The morphological comparison showed marked differences in the lengths of parts of the male genitalia, female pharynx, and spermathecae. The isoenzyme study revealed characteristic monomorphic phenotypes for glucose phosphate isomerase, hexokinase, and phosphoglucomutase in the Canarian specimens as compared with the Cretan population. These results confirm the heterogeneity of P. sergenti and indicate the utility of a systematic double approach for a revision of this taxon.

Animals↗
PubMed1990

Experimental transmission of Leishmania infantum by the bite of Phlebotomus perniciosus from Switzerland.

The possible role of the sandfly Phlebotomus perniciosus in the transmission of Leishmania infantum in southern Switzerland was investigated. It was found that the Syrian golden hamster (Mesocricetus auratus) could be infected by the bite of experimentally infected P. perniciosus females from canton Ticino, in southern Switzerland. This showed that this sandfly species could indeed be a vector for L. infantum in this area. However, as the population density of P. perniciosus is relatively low in canton Ticino, it is extremely unlikely that leishmaniasis could become endemic there.

Animals↗