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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty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 Abundance and taxonomic characterization of chigger mites (Acari: Trombiculidae and Walchiidae) associated with rodents in selected scrub typhus-prone areas in Southern and Western provinces of Sri Lanka(University of Kelaniya, 2024) Liyanage, A.; Gunathilaka, N.; Premarathne, R.; Chandrasena, N.; Jacinavicius, F.D.C.; Silva, R.B.Larval trombiculid mites (chiggers) are the vectors and reservoirs of the potentially lethal infectious disease, scrub typhus (ST) caused by Orientia tsutsugamushi. Small rodents are natural hosts of parasitic larval stage of the chigger mites. This study focused on determining the abundance of chigger mites associated with rodents in Sri Lanka and the taxonomic characterization of field-caught chiggers. Field sampling was conducted in the districts of Galle, and Hambantota of the Southern Province, and Gampaha of the Western Province, in 2019 and 2020. Sampling sites were selected according to the patient distribution. Rodents were captured using baited traps (7.62 cm x 7.62 cm x 25.4 cm) set up just before sunset at peri-domestic or work premises of ST fever patients. A total of 422 traps were placed at identified possible exposure locations in Galle (n=122), Hambantota (n=120) and Gampaha (n=178). A total of 58 small mammals were captured [Galle (n=19), Hambantota (n=7), and Gampaha (n=32)] under three small rodent species, namely; Rattus rattus (Black rat), Rattus norvegicus (Brown rat), Tatera indica (Indian gerbil), Gollunda ellioti (Indian bush rat) and Suncus murinus (Asian house shrew). The trapped rodents were anaesthetized with ketamine (75 mg/kg) /xylazine (10 mg/kg) and examined for larval mites. Mites detected were removed carefully with a brush, collected, and washed individually with 10% PBS and slidemounted in Hoyer’s medium. Chiggers were speciated morphologically by visual inspection and morphometry using a camera-mounted light microscope (x100). A total of 394 life stages of mites were collected. Three different genera were identified, including Leptotrombidium, Schoengastiella, and Microtrombicula. Leptotrombidium imphalum (72.59%; n=286) was the predominant species, followed by Schoengastiella punctata (8.12%; n=32). Some specimens were identifiable only up to genus level, Leptotrombidium sp. (3.55%; n=14) and Microtrombicula sp. (4.82%; n= 19). Some (7.11%; n=28) were not trombiculid mites, while 3.81%; n=15 was damaged beyond identification. Leptotrombidium imphalum was detected for the first time parasitizing the murids - Rattus novergicus and Tatera indica in the district of Galle, a new locality. In addition, S. punctata was recorded in a new locality in the Gampaha district, Western province with a new host association, Golunda ellioti. This study emphasizes the need for further entomological surveys in ST disease-endemic areas. Developing a morphological identification key for chigger mites in Sri Lanka is a top priority to facilitate field surveys.Item Intestinal and Ectoparasites of Human Health Importance among Stray Dogs in Galle District, Sri Lanka.(19th Conference on Postgraduate Research, International Postgraduate Research Conference 2018, Faculty of Graduate Studies,University of Kelaniya, Sri Lanka, 2018) Rathnayake, S.P.; Sudusinghe, H.P.; Nilaweera, T.H.W.T.; Marasinghe, M.A.P.; Sriyalatha, W.A.; Gunathilaka, P.A.D.H.N.Human-animal bond is a reciprocally favorable dynamic relationship which is beneficial to the health and well-being of both. Dogs have close contact with humans and play a pivotal role as definitive hosts or reservoirs for different zoonotic parasites, especially in developing countries. There are only few studies have focused on the zoonotic potential of animals in Sri Lanka. Therefore, the objective of the present study was the determine the intestinal and ectoparasites among dog population that may be important for human health. A total of 40 stray dogs captured for an animal welfare clinic conducted in Galle District of Sri Lanka was recruited for the study. Faecal samples were collected per rectal in to separate vials containing 10% formaldehyde. Ectoparasites of selected dogs were collected using a lose comb and stored in alcohol solution. The stool samples were processed by Kato-Katz techniques and intestinal parasitic stages were morphologically identified. For quantitative analysis, the modified McMaster technique was used to estimate eggs per gram of feces. The ectoparasites were characterized referring to morphological features. The results revealed eight intestinal parasites namely; Ancylostomacaninum (Prevalence: 66.75%; Eggs per gram: 362.82), Toxocaracanis (13.51%; 73.41), Enterobiusvermicularis (9.1%; 49.41), Trichurisvulpis (7.0%; 38.12), Physalopterarara (1.56%; 8.47), Paragonimuskellicotti (1.0% 5.65), Uncineriastenocephala (0.78%; 4.24) and Eucoleusaerophilus (0.26%; 1.41). The high prevalence rates of T. canis may cause visceral and ocular larva migrans to humans, which lead to blindness and A. caninum associated with hookworm related cutaneous larva migrans. Humans can be infected with T. vulpis when they accidentally ingest embryonated eggs, through contamination of infected soil, food or fomites even though it has been recorded as a rare infection. P. rara infection can be caused to humans by the accidental ingestion of arthropod hosts such as German cockroaches. In addition, the P. kellicotti, U. stenocephala, E. aerophilus and E. vermicularis may cause some health issues to humans. Even though present study did not indicate the presence of Echinococcusgranulosus which resides in the small bowel of dogs and other canids may lead to cause echinococcosis in humans. Argaspersicus (Prevalence; 34.18%) was the predominant among ectoparasites followed by Ctenocephalidescanis (32.91%) and Ixodesscapularis (32.91%). A. persicus can cause serious allergies on humans. The bites of I. scapularis may lead to cause human babesiosis (Babesiamicroti), human granulocytic ehrlichiosis (HGE); and tick-borne encephalitis (TBE). The presence of C. canis may indicate the transmission potential of Dipylidiumcaninum to humans as an occasional host. Overall, the investigation indicated that stay dogs in Galle District contain a multitude of ectoand endoparasites, thus posing a risk for the human population.