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CHARACTERISTICS OF PHLEBOTOMINE SANDFLIES IN SELECTED AREAS OF SRI LANKA.

ABSTRACT: Cutaneous leishmaniasis (CL) is an endemic disease in Sri Lanka. Studies on vector aspects, although important for better understanding of disease transmission dynamics, are still limited. The present study describes the species distribution and behavioral patterns of sandflies within selected disease-prevalent zones in the country. Adult sandflies were collected from several field sites over a two-year duration in Sri Lanka using cattle-baited net traps, CDC light traps and manual methods. Species identification was performed using standard keys. Leishmania donovani and source of blood meal in blood-fed female sandflies DNA were identified using PCR-based methods. Aggregation period of adult sandflies during overnight collections was also noted. The collected sandflies were identified as Phlebotomus argentipes glaucus (previously known as morphospecies A) and a non-vector species, Sergentomyia zeylanica. Presence of L. donovani DNA was found in 2/634 female sandflies. The parasite ITS1 region of SSU rDNA had 99% sequence similarity with L. donovani from Bangladesh and India. The peak aggregation period of sandflies within cattle-traps was between 8:00 PM to 11:00 PM, indicating that vector control strategies could be conducted during this time period. As Sergentomyia zeylanica is likely to be merely a biting nuisance and showed more of an anthropophilic behavior, whereas the probable vector of CL in Sri Lanka (P. argentipes glaucus) demonstrated zoophilic behavior, has implications for the planning of future vector control strategies.

SUBMITTER: Senanayake SA

PROVIDER: S-EPMC6206496 | biostudies-literature | 2015 Nov

REPOSITORIES: biostudies-literature

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CHARACTERISTICS OF PHLEBOTOMINE SANDFLIES IN SELECTED AREAS OF SRI LANKA.

Senanayake S A S C SA Abeyewicreme W W Dotson E M EM N D Karunaweera

The Southeast Asian journal of tropical medicine and public health 20151101 6

Cutaneous leishmaniasis (CL) is an endemic disease in Sri Lanka. Studies on vector aspects, although important for better understanding of disease transmission dynamics, are still limited. The present study describes the species distribution and behavioral patterns of sandflies within selected disease-prevalent zones in the country. Adult sandflies were collected from several field sites over a two-year duration in Sri Lanka using cattle-baited net traps, CDC light traps and manual methods. Spec ...[more]

PMID: 26867357

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Project description:Sandfly-transmitted phleboviruses, such as Toscana, sandfly fever Sicilian, and sandfly fever Naples, can cause human disease and circulate at high rates in Mediterranean countries. Previous studies have also established that viruses other than phleboviruses may be detected in and isolated from sand flies. The recent detection and isolation (in a large variety of mosquito species) of insect-only flaviviruses related to cell fusing agent virus has indicated that the latter is not an evolutionary remnant but the first discovered member of a group of viruses, larger than initially assumed, that has high genetic heterogeneity. Insect-only flaviviruses have been detected in and/or isolated from various species of mosquitoes, but nevertheless only from mosquitoes to date; other dipterans have not been screened for the presence of insect-only flaviviruses. The possible presence of flaviviruses, including insect-only flaviviruses, was investigated in sand flies collected around the Mediterranean during a trapping campaign already underway. Accordingly, a total of 1508 sand flies trapped in France and Algeria, between August 2006 and July 2007, were tested for the presence of flaviviruses using a PCR assay previously demonstrated experimentally to amplify all recognized members of the genus Flavivirus, including insect-only flaviviruses. Two of 67 pools consisting of male Phlebotomus perniciosus trapped in Algeria were positive. The two resulting sequences formed a monophyletic group and appeared more closely related to insect-only flaviviruses associated with Culex mosquitoes than with Aedes mosquitoes, and more closely related to insect-only flaviviruses than to arthropod-borne or to no-known-vector vertebrate flaviviruses. This is the first description of insect-only flaviviruses in dipterans distinct from those belonging to the family Culicidae (including Aedes, Culex, Mansonia, Culiseta, and Anopheles mosquito genera), namely sand flies within the family Psychodidae. Accordingly, we propose their designation as phlebotomine-associated flaviviruses.

Project description:BACKGROUND:Sand flies are responsible for the transmission of several disease pathogens including Leishmania. Sand flies breed in habitats with high levels of humidity and organic matter. They are nocturnal in nature and peak activity ranges from dusk to dawn. The scientific evidence on breeding ecology and diurnal resting sites of sand fly fauna are important aspects of planning and implementing vector control activities. However, such fundamental information is grossly inadequate in Sri Lanka to support the control efforts in the country. Therefore, the present study addresses some of the important aspects of sand fly breeding ecology and diurnal resting sites. METHODS:Potential resting sites were thoroughly observed, and sand flies were collected using a battery-operated aspirator and sticky papers when appropriate from three selected Medical Officer of Health (MOH) areas (Polpithigama, Maho and Galgamuwa) in Kurunegala district, Sri Lanka. Soil samples were collected from each potential breeding site. Half of each soil sample was incubated for 45 days. The other half was screened for immature stages. Adult sand flies collected from field and emerged adults at the insectary under confined incubation were identified using morphological characteristics. RESULTS:Pepper bushes and termite mounds were the most notable resting sites while, betel bushes, cattle huts, piles of coconut shells, latrines, manna bushes and tree holes were also positive for sand fly adults. Only two species, Phlebotomus argentipes and Sergentomyia punjabensis, were reported. Soil samples were collected from a total of 432 sites and 7 of them were positive for immature stages. Predominant breeding habitats identified during the present study were mud flats and moist soils of rice paddies, the soil below decaying hay, drying irrigational tank bottom moist soil, and the floors of cattle huts. CONCLUSION:This study demonstrates that the potential adult resting sites and breeding habitats are abundant in the Polpithigama, Maho and Galgamuwa MOH areas. Therefore, vector control activities targeting both adult and immature stages of sand flies are recommended.

Project description:The West Nile virus (WNV), primarily transmitted by mosquitoes, is one of the most widespread flaviviruses globally, with past outbreaks occurring in the USA and Europe. Recent studies in parts of Africa, including Kenya, have identified the West Nile virus Koutango lineage (WN-KOUTV) among phlebotomine sandfly populations, however, our understanding of this virus remains limited. This study aimed to characterize WN-KOUTV from phlebotomine sandflies. Sandflies were sampled between 12th -16th March 2021 and 16th -20th March 2023 from six villages each in Baringo and Isiolo Counties, using CDC light traps. Female sandflies were taxonomically identified and pooled based on genus and site of collection. Virus isolation was performed in Vero cells. Viral genomes were determined using next-generation sequencing. Phylogenetic and molecular clock analyses were done to decipher the virus's evolutionary relationships. Comparative analyses of amino acid sequences were performed to determine variations. Protein modeling in Pymol was conducted to elucidate variations in key protein regions. Evolutionary pressure analysis investigated the selection pressures on the virus. In vitro experiments were done to investigate the virus growth kinetics in mammalian Vero E6 and mosquito C6/36 cells. We report the isolation of WN-KOUTV from Salabani in Baringo and Aremet in Isiolo, Kenya. The isolated WN-KOUTVs clustered with previously identified WN-KOUTV strains. Comparative analysis revealed a unique amino acid at NS5 653. The WN-KOUTV lineage as a whole is under purifying selective pressure, with diversifying pressure acting at site NS3 267. The current WN-KOUTV replicated in Vero E6 and C6/36 cells comparable to West Nile virus Lineage 1a, isolated from mosquitoes. Subsequent isolations of WN-KOUTV in phlebotomine sandflies suggest potential vectors, however, vector competence studies would confirm this. Replication in mammalian and insect cell lines suggests there may exist a vector/host relationship. We speculate the close genetic relationship of WN-KOUTV strains from East and West Africa may potentially be enabled by bird migratory routes between the two regions. If proven, this could point to a potential future pandemic pathway for this virus.

Project description:BackgroundAntibodies against the merozoite surface protein 1-19 (MSP1-19) and the apical membrane antigen 1 (AMA1) of the malaria parasite (Plasmodium vivax) are proven to be important in protection against clinical disease. Differences in the production/maintenance of antibodies may be due to many factors including host genetics. This paper discusses the association of 4 anti-malarial antibodies with selected host genetic markers.MethodsBlood was collected from individuals (n = 242) with a history of malaria within past 15 years for DNA and serum. ELISA was carried out for serum to determine the concentration of anti-malarial antibodies MSP1-19 and AMA1 for both vivax and falciparum malaria. 170 SNPs related to malaria were genotyped. Associations between seropositivity, antibody levels and genetic, non-genetic factors were determined.ResultsAge ranged 13-74 years (mean age = 40.21 years). Majority were females. Over 90% individuals possessed either one or more type(s) of anti-malarial antibodies. Five SNPs were significantly associated with seropositivity. One SNP was associated with MSP1-19_Pv(rs739718); 4 SNPs with MSP1-19_Pf (rs6874639, rs2706379, rs2706381 and rs2075820) and1 with AMA1_Pv (rs2075820). Eleven and 7 genotypes (out of 15) were significantly associated with either presence or absence of antibodies. Three SNPs were found to be significantly associated with the antibody levels viz. rs17411697 with MSP1-19_Pv, rs2227491 with AMA1_Pv and rs229587 with AMA1_Pf. Linkage of the markers in the two groups was similar, but lower LOD scores were observed in seropositives compared to seronegatives.Discussion and conclusionsThe study suggests that several SNPs in the human genome that exist in Sri Lankan populations are significantly associated with anti-malarial antibodies, either with generation and/or maintenance of antibodies for longer periods, which can be due to either individual polymorphisms or most probably a combined effect of the markers.

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CHARACTERISTICS OF PHLEBOTOMINE SANDFLIES IN SELECTED AREAS OF SRI LANKA.

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CHARACTERISTICS OF PHLEBOTOMINE SANDFLIES IN SELECTED AREAS OF SRI LANKA.

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