Medicine
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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty
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Item Parasitological screening of vector mosquitoes and molecular biological identification of larval filarial parasites among the wildcaught Mansonia mosquito species at selected areas in the district of Gampaha, Sri Lanka, a re-emerging focus of Brugian filariasis(University of Kelaniya, 2024) Gunathilaka, N.; Wimalasiri, U.; Chandrasena, N.; Dalpadadu, R.Brugian filariasis, a disease caused by the Protozoan parasiteBrugia malayi has re-emerged in Sri Lanka after nearly four decades of quiescence. The Brugia malayi that prevailed in Sri Lanka in the past was the nocturnal periodic human strain transmitted by mosquitoes of the genus Mansonia. The objective of the present study was the precise identification of vector mosquitoes and parasites of the current onset of the disease. Entomological surveys were performed during September/October 2021 in Ragama Medical Officer of Health area using cattle-baited net traps. Mansonia sp. mosquitoes were dissected to detect the presence of larvae of the parasite. The lysate of dissected mosquitoes positive for larvae was used for the extraction of genomic DNA of the parasite, which was subjected to Polymerase Chain Reactions (PCR) aimed at molecular speciation using pan-filarial primers specific for the internal transcribed spacer region two (ITS2) of the ribosomal DNA. A total of 1060 mosquitoes were tested, and that included seven mosquito species belonged to four genera. Culex gelidus (n=602; 56.8%) was detected as the predominant mosquito species followed by Armigeres subalbatus (n=420; 39.6%) Cx. tritaeniorynchus (n=2; 0.2%) and Anopheles nigerrimus (n=4; 0.4%). Mansonia spp. accounted for 2,7% of the total mosquito sample and among them, the presence of Mansonia annulifera was 1,2% of the total (n=20), Ma. uniformis was 0.9% (n= 10) and Ma. Indiana was 0.2% (n= 2). About 18.7% (n=6) of Mansonia mosquito collection was positive for filarial larvae. Among them, 15.6% (n=5) was Mansonia annulifera while (3.1%; n=1) was Ma. uniformis. The PCR products of all tested samples corresponded to the band size of 625 bp, specific to B. malayi confirming the identity of the parasite. Mansonia annulifera and Ma. uniformis were confirmed as vectors of the re-emerged B. malayi (nocturnally sub-periodic) in Gampaha district. The role of other mosquito vector species would require investigation by vector incrimination and xenomonitoring-based approaches.Item Canine filaria species in selected lymphatic filariasis endemic and non-endemic areas in Sri Lanka(Springer International, 2022) Rathnayake, S.; Chandrasena, N.; Wijerathna, T.; Mallawarachchi, H.; Gunathilaka, N.Subperiodic brugian filariasis and dirofilariasis show a rising trend in Sri Lanka posing a threat to public health. As information was limited on canine filaria species in Sri Lanka, we studied the filaria parasites among dog populations in lymphatic filariasis (LF) endemic and non-endemic regions by microscopy and molecular methods. Thick blood smears (TBSs) were performed among 295 dogs presenting to veterinary clinics for surgical or sterilization procedures in Galle (LF endemic) and Mullaitivu (LF non-endemic) districts, of which 55.6% were positive for any microfilariae. We identified Dirofilaria repens (50.8%) and Brugia spp. (20.6%) by microscopy, which, included mono-infections (D. repens 35.3% and Brugia spp. 5%) and co-infections (15.6%). Infections in Galle and Mullaitivu were 61% and 44.9% respectively. The brugian filariasis rate was significantly higher among canines in LF endemic Galle district (29.9%) than in Mullaitivu (LF non-endemic) (1.1%) (P < 0.001), while D. repens infections were comparable in both districts. Genomic DNA extracted from 10% of microfilariae positive TBSs was amplified using pan-filarial primers targeting the internal-transcriber-spacer region-2 (ITS-2). Sequencing of amplicons confirmed the presence of D. repens (89.28%), Brugia pahangi (7.14%) and B. malayi (3.57%) infections. The phylogeny constructed and analysed in MEGA X indicated genetic variability among D. repens and B. pahangi isolates from Sri Lanka. With this study, we were able to report B. pahangi infections for the first time in Sri Lanka.