Search

Sandflies are the main vectors of Leishmania parasites in tropical and subtropical areas. The immunization of vertebrate hosts with vector components through repeated bites may offer an alternative method for sandfly control. Aliquots of female Phlebotomus papatasi (Scopoli) (Diptera: Psychodidae) were weekly blood fed on 12 individual hamsters throughout 18 successive weeks. Significant biological and biochemical changes resulting from antibodies developed by immunized host sera against repeated biting were observed in sandfly females. Blood feeding and fertility rates of females significantly gradually declined to the end of the study period. No appreciable difference was observed in mortality rates among flies repeatedly fed on individual hamsters throughout weeks 9 and 18, compared to flies fed on naive hamsters. Total salivary gland proteins of female sandflies were compared to proteins in sera of sensitized hamsters. SDS-page revealed bands common to both flies and hosts, indicating the development of anti-saliva antibodies in hamster sera. The importance of anti-sandfly saliva antibodies as a potential tool for vector control leading to the interruption of leishmaniasis is discussed.

Alzheimer's disease (AD) is an irreversible neurodegenerative disease. Recent identification of AD biomarkers has led to the diagnosis of AD before the onset of dementia. It has been shown that Drosophila melanogaster is a valuable model for studying human neurodegeneration, including AD. According to its properties, curcumin shows promising potential for the diagnosis of AD. In order to improve its use, new formulations, including nanotechnology-based delivery systems, have been applied. The current study aims to diagnose AD by detecting the accumulation of amyloid beta-peptide via carbon-dot-curcumin nanoparticle conjugation in Drosophila. The accumulation of amyloid beta-peptide has been detected via the conjugate using the fluorescence imaging technique. These results suggest that carbon-dot-curcumin nanoparticle conjugation could be used as a diagnostic tool for AD.

Phlebotomus papatasi is one of the common sand flies that found in Egypt. Three to five- days old 1080 non infected P. papatasi sandfly females were used in this study. They fed for 90-100 min. on blood of non immunized hamster for one time/week. Each hamster was re-exposed for an average of 18 exposures at one week interval after being immunized. immunized. Sand flies were observed to determine their biting activity as Fed or Half-fed. Then sera of control and immunized hamster was analyzed by using spectrophotometer. Three replicates of sand flies groups (each with 360 insects) were used. The results indicated a remarkable change in biting activity of sand flies through the investigated period (18 weeks) where a powerful biting through the first seven weeks was observed, followed by a significant decrease in number of biting activity during the rest of weeks. This can be explained by acquiring hamster immunity due to formation of antibodies in his blood. Multiple exposures to sandfly saliva induce an immune response in hamster which can control leishmaniasis in this animal. This immune response was reflected in results of total protein estimation where the total protein increased after successive bits compared to control. Therefore, we could concluded that the antibodies which have been formed in hamster against saliva of female sandfly have a repellent effect as well as immunized effect. Knowledge to be gained from the present study will contribute to recent trends in the future development of novel strategies for preventing disease transmission in Egypt.

Phoresy is a biologically mechanical phenomena where an immobile organism hitches on a other mobile organism to translocate. This behaviour is not studied very well on the field level especially between two important parasites infesting the same host. Parasite/parasite interaction is rarely studied through most biological host-parasite systems. Here, we evaluated the phoretic relation between parasitic chewing lice and hippoboscid flies (Pseudolynchia canariensis) on rock pigeons. A total of 69 captivated rock pigeons, Columba livia, were examined for the parasitic chewing lice and hippoboscid flies in Giza Zoo and two local farms near Cairo, Egypt. Results indicated that there is a positive correlation between infestation of hippoboscid flies and chewing lice. Also, the analysis of louse/louse interaction using ANOVA indicated a significant difference between the three chewing louse species which were recorded on the rock pigeons with relatively high abundance of two species, Columbicola columbae and Campanulotes compar. The analysis of hippoboscid flies' abundance and its relation with chewing lice infestation indicate a significant increase of lice intensity in case of high infestation with the fly. The level of hygiene of nest may be inversely related to level of parasite infestation. This work forms a step in the process of understanding parasite/parasite and host/parasite interactions using two parasitic species with a characteristic phoretic behaviour in nature.

Little information is available about the chewing lice of wild birds of Egypt, including common groups such as pigeons and doves (Columbiformes). Through this work, parasitic chewing lice of common columbiformes of Egypt were revised including new data. Three species of pigeons and doves (Streptopelia decaocto Frivaldszky 1838, Spilopelia senegalensis Linnaeus 1766 and Columba livia Gmelin 1789) were examined for chewing lice at three different localities. A total of 124 specimens of lice were collected. Nine species were identified from these samples; one species (Columbicola joudiae n. sp.) was considered a new species to science, six species were recorded from Egypt for the first time, and two species have been identified in Egypt before. Taxonomic and ecological remarks for all identified chewing lice samples are provided along with known and local hosts, measurements and material examined. Description and images of the new species are also provided.

Sand fly salivary fluid contains numerous proteins that modulate host immune responses to infection and facilitate blood-feeding and establishing Leishmania infection. Salivary proteins are differentially expressed in adaptation to the host, the meal type and ecological factors. We report on the morphometrics and protein composition of salivary glands of colonised Phlebotomus papatasi and P. langeroni sand flies from Egypt. Female glands were dissected at day 1 (D1, unfed), day 2 (D2, sugar-fed), day 3 (D3, blood-fed) and day 7 (D7, blood-digested). The salivary glands are composed of two lobes: heterogeneous in P. papatasi and homogeneous in P. langeroni. Lobe sizes varied considerably with fly age and feeding state; D3 flies had the largest lobe sizes and protein content. The P. papatasi flies had larger lobes and higher protein content than the P. langeroni flies. The P. papatasi D1 flies had 15 protein bands that decreased in the D2, D3 and D7 flies to 10 bands in the Sinai flies and 9 bands in the Alexandria flies. All P. langeroni flies had 12 protein bands but with different intensities. The results reveal inter-specific variation between P. papatasi and P. langeroni, while no intra-specific variation between P. papatasi strains. These results increase our understanding of salivary gland protein composition and blood-feeding behaviour in Old World sand flies with implications for leishmaniasis epidemiology and control.

Cutaneous leishmaniasis (CL) is prevalent in the Egyptian Sinai Peninsula and previous research has consistently documented the etiologic agent to be Leishmania major. We report the first isolation of Leishmania tropica from human cases of CL in a Northern Sinai community bordering Palestine. Parasite culturing, real-time polymerase chain reaction (PCR), gene sequencing, and restriction fragment length polymorphism (RFLP) analyses indicate CL cases in this community were caused by either L. major or L. tropica (three cases each). Two wild-caught rodents (Gerbillus pyramidum floweri) were infected with L. tropica. Phlebotomus papatasi sand flies were found harboring L. major, however only non-infected individuals of Phlebotomus sergenti, a vector for L. tropica, were caught. Patients with L. tropica had not traveled from the region in over a year, suggesting these cases are autochthonous. This scenario is consistent with an incursion of L. tropica from bordering countries and raises concerns about expansion of this parasite further into Egypt.

Cutaneous leishmaniasis (CL) is a neglected clinical form that is quite prevalent in Eastern North parts of the country in Sinai Peninsula. Leishmania tropica was identified by previous reports as the causative agent responsible for viscerotropic infections in-patients and experimental animals. Here, we reported the viscerotropic infections from naturally infected rodent Gerbillus pyramidum floweri collected from North-Sinai. Footpad and tail lesions, spleenomegaly, and malformed dark-colored spleen were the characteristic CL symptoms. The spleen of the rodent found positive to amastigote impression smear. ITS-1 DNA was sequenced and revealed 100% identity of the strain in the current study to the other L. tropica sequences identified from the patients with the suspected CL and inhabited the same study area. The current findings confirmed the susceptibility of gerbil to L. tropica, and raise the concerns for the role of rodents as accidental host suffering the infections. The susceptibility of wild and experimental rodents to the same L. tropica strain was also investigated; BALB/c and G. pyramidum were more susceptible to L. tropica (24.33 ± 4.37 and 25 ± 4.58 days post-infection, respectively). Similar viscerotropic pathologies were reported in experimental infection of only golden hamster (≈ 120 days post-infection), and G. p. floweri (≈ 160 days post-infection).

Trials were conducted to determine the accuracy of separating the sympatric sand fly species Phlebotomus papatasi (Scopoli) and P. langeroni Nitzulescu by means of cellulose acetate enzyme electrophoresis. Malic enzyme, phosphoglucomutase, 6-phosphogluconate dehydrogenase, and fumarate hydratase were each evaluated in laboratory-reared and field-collected populations of the two species. Each of the four enzyme-based identifications was highly sensitive (greater than 97%) and specific (greater than 93%). Identifications based upon fumarate hydratase were in perfect agreement with morphological identifications, and evidence was obtained which indicates that this enzyme may be the most stable of the four enzymes tested. The application of enzyme-based vector identification is discussed in relation to classical and novel survey procedures for Leishmania promastigote detection in sand flies.

(1996). The prevalence of a microbiota in the digestive tract of Phlebotomus papatasi. Annals of Tropical Medicine & Parasitology: Vol. 90, No. 6, pp. 669-673.

Phlebotomus papatasi and P. langeroni were infected with Leishmania major and L. infantum by membrane feeding. Each sand fly ingested approximately 200 parasites per blood meal. Higher mortality in both sand fly species was seen with mixed infections than with a single parasite species. There was no significant difference between infections with either L. major or L. infantum in their natural vectors or experimental hosts. Infection significantly depressed the mean number of eggs laid per female.

Cellulose acetate electrophoresis was employed to detect 22 different enzyme systems in laboratory-reared populations of the sympatric Leishmania vectors, Phlebotomus papatasi (Scopoli) and P. langeroni Nitzulescu. Electrophoretic conditions sensitive enough to permit as many as eight separate enzyme assays to be performed on individual specimens were developed. Under these conditions, 18 enzymes were detected with high resolution and regularity. Evidence was obtained which suggested that a number of enzymes in both species are under multilocus genetic control. Polymorphism was observed in 14 of 25 (56%) loci detected in P. papatasi and in eight of 24 (33%) loci detected in P. langeroni. Differences in electrophoretic profiles of malic enzyme, 6-phosphogluconate dehydrogenase, and fumarate hydratase were considered to be genetically fixed in both sexes of P. papatasi and P. langeroni. Their detection may permit an accurate and more rapid separation of these vectors in field collections.

SUMMARY. We have done a laboratory study on the biology of Phlebotomus langeroni which was first recorded in El Agamy area, Alexandria, Egypt, where visceral leishmaniasis occurs. The fecundity, longevity and productivity were investigated in relation to the type of blood meal (human, guinea pig and chicken). Fecundity was significantly higher when females were fed on human than on chicken and guinea pig blood, where the mean number of eggs laid per female was 62.6 ± 1.9, 56.6 ± 6.9 and] 47.5 ± 3.2 [respectively. Females fed on human lived longer than those fed on guinea pig or chicken (14.1 ± 0.2, 10.7 ± 0.4 and 7.6 ± 0.3 days respectively). There was a marked prolongation in larval development in case of guinea pig fed female than the two other cases (27.8 ± 0.8, 24.1 ± 0.5 and 24.0 ± 0.8 days respectively. The nature of blood meal of the mother do not affect the pupal duration. The productivity (the number of adults produced from eggs of individual females) decreased significantly from human (28.4 ± 2.3) to guinea pig (16.0 ± 2.3), and chicken (13.8 ± 4.1). The high productivity of females fed on human and the anthropophilic feeding tendency, may account for the efficiency of P. langeroni as a vector of human diseases.

The dot enzyme-linked immunosorbent assay (dot-ELISA) was compared to the indirect immunofluorescent assay (IIFA) and radioimmunoassay (RIA) for the detection of malaria antibodies. Of 281 sera tested by dot-ELISA, 220 were from Ethiopia, 11 from the Sudan, and 50 from Egypt. A close correlation between the dot-ELISA and RIA results was observed in 92% of the 220 Ethiopian cases. Of the remainder, 6% gave positive RIA and negative dot-ELISA results, and 2% gave positive dot-ELISA and negative RIA results. Antibody titres determined by dot-ELISA and RIA were positively correlated in 10 of the 11 Sudanese cases tested by direct microscopical examination. The eleventh case was positive by dot-ELISA at 1:1000 dilution, but negative by RIA and direct examination. With the 50 Egyptian sera, the dot-ELISA results showed close correspondence to the IIFA results, but the dot-ELISA was 20–40 fold more sensitive than the IIFA. To test specificity, 62 samples from patients with 11 different diseases and conditions were examined by dot-ELISA. No malaria antibodies were detected in any of these or in sera from healthy controls. Dot-ELISA is a potentially useful method for sero-epidemiological studies of malaria.

A community-based malaria control programme initiated in Saradidi, Kenya in 1982 is described. Antimalarial treatment provided by volunteer community health workers was made available in each village. Malaria was holoendemic. Parasitaemia rates by age were high and did not change after the control programme began. Plasmodium falciparum was the most common species and was present alone or mixed in 98.2% of 8105 infections. Virtually all (98.5%) of 2040 blood samples collected in May 1981 were positive (reciprocal titre greater than or equal to 80) to P. falciparum by the indirect fluorescent antibody (IFA) test. Seropositivity rates to P. falciparum in the IFA test or the enzyme-linked immunosorbent assay (ELISA) were high in all age groups and did not change significantly in longitudinal surveys or in a cohort of children zero to nine years old followed at intervals. While the malaria control programme was successful in bringing treatment to each village, malaria prevalence was not reduced. Parasitologic and serologic studies alone were not adequate to describe the impact of the community-based malaria control programme in Saradidi. Morbidity and mortality rates caused by malaria can decline, significantly improving the health of the population, in the absence of any decrease in parasitaemia rates.

Laboratory bred Phlebolomus papatasi and P. langeroni were examined for their susceptibility to develop Leishmania major promastigotes under laboratory conditions. Promastigotes were demonstrated in the gut of both species when they were given sugar 24 hr before or after an infective blood meal and in flies offered only an infective blood. The overall infection rate was slightly higher in P. langeroni than P. papatasi. Head promastigotes were detected in P. papatasi provided with sugar 24 hr before or after an infective blood meal. No head promastigotes were seen in flies offered only infective blood. In P. langeroni, head promastigotes were only seen in flies fed on sugar before or after an infective blood and maintained at 18 degrees C. Results indicate that sugar plays a major role in the migration of parasites from the gut to the head. Temperature may have a marginal effect on the migration process. Attempts to transmit L. major to hamster by the bite of infected P. papatasi were not successful.