International Research Symposium on Pure and Applied Sciences (IRSPAS)

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    Breeding sites of Phlebotomine sand flies in cutaneous leishmaniasis disease endemic areas of the Kurunegala District in Sri Lanka
    (Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Wijerathna, T.; Gunathilaka, N.; Gunawardena, K.; Rodrigo, W.
    Leishmaniasis is a disease transmitted by the bite of infected female sand flies. Disease control largely depends on the knowledge on natural breeding sites of sand flies. In Sri Lanka, only limited information is available on microhabitats of immature sand flies. Therefore, the present study was conducted to identify natural breeding habitats of sand flies in three cutaneous leishmaniasis endemic areas, namely; Galgamuwa, Polpithigama and Maho in the Kurunegala District of Sri Lanka. Study areas were selected based on the number of patients reported to respective Medical Officer of Health (MOH) during the year 2013 - 2016. A preliminary survey was conducted in April 2017 and possible breeding sites were identified for the survey based on field investigations and previous literature. A breeding habitat checklist was prepared for main habitat categories. Field investigations for immature stages were conducted on a monthly basis from May 2017 - June 2018. Three soil samples were collected randomly from each potential breeding habitat and transported to the laboratory. The soil samples were divided into equal portions, and immature stages of sand flies in one portion were screened by direct microscopic examination and sugar flotation method. The rest of the soil samples were incubated at 260C and 75-80% Relative Humidity (RH) under confined laboratory conditions for adult emergence. Adult sand flies were identified using morphological identification keys. A total of 433 potential breeding sites were surveyed under 21 habitat categories. Of them, soil mounds were predominant (n=51) followed by leaf litter (n=46), termite hills (n=42) and tank/river margins (n=36). However, only four habitat types were positive for immature stages of Phlebotomus argentipes, namely; paddy fields (n=5/10), moist soil in dried tanks (n=2/12), soil beneath decaying organic matter (n=2/7) and cattle huts (n=1/23). All positive sites were enriched with organic matter containing moderate moisture levels. However, further studies are required to understand the physiochemical parameters of breeding sites and by that minimize the sand fly population through management of habitat conditions.
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    Influence of humidity and temperature variation of natural breeding sites on abundance of Leishmaniasis vector Phlebotomus argentipes population in Anuradhapura District
    (Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Nayakarathna, N.M.N.G.; Ganehiarachchi, G.A.S.M.; Rajapakse, R.P.V.J.; Jayanetti, S.R.
    Cutaneous leishmaniasis (CL) is an endemic public health problem in Sri Lanka. Leishmania donovani is the suspected causative agent of the disease and this parasite is transmitted by a dipteran fly species; Phlebotomus argentipes. Studies on vector behavioral and ecological aspects, although important for better understanding of disease transmission, are still limited. The present study is an attempt to uncover the vector ecological aspects focusing on the successful vector control interventions. This study is being carried out in Anuradhapura district, Sri Lanka; where there is a high disease prevalence of CL. Three sampling sites; Thalawa, Wijayapura and Padawiya were selected. Adult sand flies were collected monthly over a six months duration using CDC light traps (5) and yellow sticky traps (30). In the meantime, relative humidity and air temperature were measured using hygrometer and thermometer in each site. The collected sand flies were identified up to the species level using standard keys. Percentage composition of each of the species was calculated. Temporal variations of primary vector, Phlebotomus argentipes along with the dynamics of temperature and relative humidity was determined using regression analysis. Phlebotomus argentipes was the dominant sand fly species found in the study sites. The percentage composition of the primary vector exhibited a variation during the study period and maximum percentage composition was recorded during May and June, 2016. The relationship between percentage composition of Ph.argentipes versus mean temperature was significant (P = 0.000, R2 = 97.7%) and elevated percentage composition were recorded under lower temperature. Further, percentage composition of Ph.argentipes exhibited an increasing trend with higher humidity levels (P = 0.000, R2= 98.4%). In conclusion, the primary vector populations of leishmaniasis are increased with lower temperature and higher humidity. As such, this relationship will helpful to predict the variation of vector population with the changes of ecological parameters and finally a successful vector management strategy can be implemented with the thorough knowledge of its life history parameters and behavioral pattern.