Browsing by Author "Dassanayake, R."

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Establishment and maintenance of laboratory colonies of Aedes albopictus mosquitoes
(University of Peradeniya, 2015) Wijegunawardana, A.D.; Gunathilaka, H.N.; Dassanayake, R.; Gunawardene, Y.I.N.S.; Abeyewickreme, W.
With a mission of "providing authenticated, high-quality Aedes albopictus mosquito rearing information to the research community" maintenance of a Ae. albopictus mosquito colony was started. All environmental facilities inside the insectary were carefully maintained to better suit the Ae. albopictus mosquito colonization. The mean temperature of 27°C (± 0.5°C) was constantly maintained inside the insectary. Wet towels on adult mosquito cage racks were used for proper maintenance of humidity. Lighting was using fluorescent light and regulated with 16:8 hour continuous dark and light period. Pest insect was controlled to ensure essential absence of ants and cockroaches. This was achieved without any harm to the mosquito colonies either directly or by contamination with toxicants transported by pests. An adult mosquito trap placed inside the insectary was used to monitor released mosquitoes. Consistent effort was also made to improve the level of cleanliness inside the insectary. Written guidelines were given to each person responsible for a task. Insectary operations included egg counting, preparation of hatching bottles with boiled distilled water following cooling to room temperature, egg hatching, larvae rearing with International Atomic Energy Agency (IAEA) recommended diet of tuna meal, bovine liver powder, brewery yeast and vitamin complex in a ratio of 37.5:27:10.5:2 g in 1L up to one week, pupae counting and putting into adult emergency cages, adult male feeding with 10% sugar solution with Vitamin complex, adult female blood feeding from 4th day onwards with bovine blood, placing egg laying cups and collecting egg laying cups, drying egg papers and starting next generation from the dried eggs. Adult mosquito cages were blood fed every 4th day after emergence from pupa and for quality control reasons each adult cage was blood fed only 3 times and there after only 10% sugar solution with vitamin syrup was supplemented until all adult mosquitoes died. Documentation for maintenance and data record was maintained and updated daily. Records included larvae feeding records, larvae tray maintenance and cleaning charts, adult feeding records with both sugar solution and blood, insectary cleaning records with time and dates. Number of eggs and percentage of egg hatching, larvae death, pupation, adult emergence, egg laying and adult mosquito death with respect of the sex and time difference were recorded. For bio-safety reasons all discarded material from larvae trays, egg laying cups and adult cages were boiled thoroughly to facilitate total destruction of the contaminated mosquito eggs. All other infectious material were incinerated. Finally, all above conditions facilitated achievement of 100% egg hatching rate within maximum of 24 hours, 100% survival of larvae to pupa (~ 7 days), 100% survival of pupated larvae to adult emergence (~ 2 days) and 95.5% adult survival up to 12 days. No difference was observed on adult longevity between males and females within first 12 days of adult emergence. However, approximate life span for males (-17 days) was lower than the females (~ 25 days) and the mortality was regular through all generations (Fl to F21).
Hepatitis B and Hepatitis C virus infections among patients with chronic kidney disease from two presumed high-risk centers
(Sri Lanka Medical Association, 2018) de Silva, S.T.; Perera, P.S.; Anuruddhika, H.W.D.; Dassanayake, R.; Niriella, M.A.
INTRODUCTION AND OBJECTIVES: Community prevalence ofhepatitis-C (HCV) and hepatitis-B (HBV) infection is low in Sri Lanka. Patients with chronic kidney disease (CKD) are at high-risk for HBV and HCV infections. We determined the prevalence and risk factors for HBV and HCV among CKD patients in two Teaching Hospitals. METHODS: This cross-sectional, descriptive study was carried out among CKD patients at Nephrology Units in Polonnaruwa and Ragama Teaching Hospitals. CKD was defined as estimated glomerular filtration rate <60ml/min/1.73m2. Consecutive, consenting adult CKD patients with at least one blood transfusion during the past five years were included. All participants were tested for HBsAg and HCV antibodies by ELISA. Those found to be positive for either underwent confirmatory PCR testing. RESULTS: 232 patients were included [Mean-age: 55.83 years; 156 (59.75%) males]. Diabetes mellitus and/or hypertension were the causes of CKD in 137/232 (59.1%). 82/232 (35.3%) had CKD of uncertain aetiology.153/232 (65.9%) were on hemodialysis and 6/232 (2.6%) had received a kidney transplant. One was an intravenous drug user, 3 had tattoos and 86/232 (37.1%) had practiced unsafe sex previously. 145/232(62.5%) had previously received HBV vaccination and 67/232 (28.9%) had received 3 doses of the vaccine before first blood transfusion, hemodialysis or transplant. Sero-conversion testing was not done in 178/232 (76.7%). Six were previously HBsAg positive. On re-testing 4 were positive for HBsAg While none had HCV antibody positivity. All were negative for HBV-DNA on PCR testing. CONCLUSION: Active HBV,HCV infections were not detected in this cohort of CKD patients. Traditional risk factors were uncommon. Complete HBV vaccination was suboptimal and checking for seroconversion was low.
A preliminary community survey of selected dengue patient households in the Ragama MOH, Gampaha District
(Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2016) Wijegunawardana, N.D.A.D.; Gunathilaka, N.; Udayanga, L.; Gunawardene, N.; Dassanayake, R.; Chandrasena, N.; Bourtzis, K.K.; Abeyewickreme, W.
Socio-economic aspects of the local population has been found to directly influence the emergence of dengue epidemics. Thus, a preliminary community survey was conducted among 30 randomly selected dengue positive patient households in the Ragama Medical Officer of Health (MOH) area, in Gampaha District to assess the socio-economic and demographic level of the patients. Study premises were selected randomly based on the MOH records during the year of 2015 and the selection of the premises was purposely limited to Narangodapaluwa Public Health Inspector area that has reported the highest number of dengue cases. An interviewer administrated questionnaire was used for the collection of socio-economic and demographic aspects of the patient households. Among the selected households; 40% (n=12) had at least more than 2 dengue positive patients among the occupants, while 42 dengue positive patients were interviewed in total. Age distribution of positive patients ranged from 1 - 70 years, while mean and mode represented 35 and 19 years, respectively. Relative distribution of male to female ratio remained as 1:1. Around 50% of the patients had an educational level higher than intermediate school education (O/L). Based on the indirect questions regarding the possible factors affecting the DF transmissions, it was noted that only participants 26 out of 42 (61.90%), have been infected with DF more than once in their life time regardless of living in the same study area since birth. Twenty-two patients (52.38%) claimed that they believe, that the DF infection has acquired at home. Meanwhile others claimed (n=20, 47.68%) that possible DF infection acquired site could be outside environments, probably schools or the place of work. Cleanliness of the surroundings was maintained well at almost all households, while waste disposal was properly maintained at weekly intervals by urban council in 14 premises. Others practiced open ground burning twice a week. Most of the respondents were willing to support Aedes control measures and follow mosquito bite prevention methods (n=28, 93.33%). Majority of the households (n=21) were not satisfied with the government vector controlling activates within the area. There is no significant association between socio demographic and economic data with DF transmission within the study population. Relative abundance of Aedes mosquito population in existing rubber plantation could be a reason for the occurrence of high rate of DF cases. Thus, practice of effective integrated vector control measures within the study area is highly recommended for the controlling of dengue.