Browsing by Author "Rajapakse, R.P.V.J."

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Contribution of rickettsioses in Sri Lankan patients with fever who responded to empirical doxycycline treatment
(Oxford University Press, 2010) Premaratna, R.; Rajapakse, R.P.V.J.; Chandrasena, T.G.A.N.; Nanayakkara, D.M.; Bandara, N.K.B.K.R.G.W.; Kularatne, S.A.M.; Eremeeva, M.E.; Dasch, G.A.; de Silva, H.J.
Twenty-eight febrile Sri Lankan patients with undiagnosed fever for 7 days after hospital admission, who responded to empirical treatment with doxycycline, were retrospectively investigated using microimmunofluorescence assay to verify whether they had rickettsial infection. Eleven (39%) patients were confirmed as having spotted fever group rickettsioses and 10 (36%) as having Orientia tsutsugamushi. Seven were negative for all tests. This suggests that greater use of doxycycline appears justified for patients with undiagnosed fever in settings where rickettsial diseases are endemic or re-emerging with inadequate diagnostic facilities.
Cytotoxic effects of α-Eleostearic acid-rich fat extracted from seeds of bitter melon (Momordica charantia) on Vero 76 cells
(Faculty of Graduate Studies, University of Kelaniya, 2015) Ranasinghe, K.N.K.; Jayasooriya, A.P.; Premachandra, T.N.; Hilmi, A.J.; Kularatne, S.A.M.; Madhujith, T.; Rajapakse, R.P.V.J.
Some seed fat sources contain conjugated trienoic fatty acids in high proportions (30- 80%). Previous studies have revealed that these fatty acids possess potent anticarcinogenic properties. The bitter melon (Momordica charantia) seed fat contains a conjugated trieneoic fatty acid named α - Eleostearic acid (α – ESA; 18:3;9c,11t,13t). The reported proportion of α-ESA in the fatty acid profile ranges from 50% - 60% and it is consistent with our study giving a result of 50.56%. Thus, the current in vitro study was conducted to evaluate the cytotoxicity of α-ESA-rich fat using a continuous cell line named Vero 76. It has been previously suggested that Vero cells can be used for preliminary studies in cancer research in vitro. For the in vitro evaluation, fatty acid methyl esters (FAMEs) of bitter melon seed fat (BMO) was prepared and was incorporated into the cell line with RPMI 1640 medium (10μl FAME + 90μl RPMI medium). As a control, FAMEs of coconut fat (Cocos nucifera; CO) was incorporated (10μl FAME + 90μl RPMI medium) into growing cells. Furthermore, in the positive control, Absolute Ethanol (100 % Ethanol) was added (100μl) and in the negative control 100μl of RPMI medium was added. MTT assay was conducted after 24 hours incubation. Finally Absorbance (A) was measured at 570 nm. The results revealed that Vero cells treated with FAMEs of BMO have exhibited a significantly less cell viability (A = 0.2138) as compared with cells treated with FAMEs of CO (A = 0.8475). The viability of cells treated with FAMEs of CO was comparable with the negative control (A = 1.027). Interestingly, the viability of cells treated with FAMEs of BMO was comparable with the positive control (A = 0.2443) indicating a potent cytotoxicity on these cells. BMO exhibited a significant cytotoxic action compared with CO. As Vero cells have been recognized a suitable cell culture for preliminary cytotoxicity studies, these results pave the way for further studies on this cytotoxic conjugated fatty acid using cancer cell lines in vitro.
Effect of The Domestic Characteristic on Colonization of Phlebotomine Sand Flies: A Case Study in Anuradhapura District, Sri Lanka
(Faculty of Graduate Studies, 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 vector-borne disease in Sri Lanka.It is caused by protozoan parasite Leishmania species and transmitted via infective bite of female Phlebotomine sand flies (Diptera: Psychodidae). The public health importance of this disease is positively increasing due to inadequate knowledge of vector biology. The current study is an attempt to uncover the vector biological aspects, focusing on the successful vector control interventions. This study was carried out in Anuradhapura district, Sri Lanka; a district with high disease prevalence of CL. Three sampling localities were selected; Thalawa, Padawiya and Wijayapura. A questioner and field studies were carried out in the sampling areas among CL patients to assess the effect of domestic environment characteristics on colonization of phlebotomine sand flies. Presence of decaying garbage, termite hills, manna grass (Glyceria sp.), water streams, unclear areas, wet soil areas, scrub jungles and gardening areas are the concerned characteristics for the present study. Field studies were conducted every month for seven months continuously. In every visit, Phlebotomine sand fly samples were collected from the study sites mentioned above using yellow sticky trap method. Increment of the mean number of sand fly population alongwith the increment of the number of domestic characteristics was tested with the regression analysis.With the increment of supportive environmental characteristics, sand fly populations were increased linearly (P = 0.000) in each site. This relationship revealed that the maximum sand fly populations were recorded in the places with all the tested characteristics stated above. Accordingly, the surrounding characteristics of the domestic environment have a significant effect on the colonization of sand fly populations. Domestic characteristics such as decaying organic matter, wet soil, unclear areas and water streams around the living environment show higher contribution to the colonization of sand flies. In conclusion, characteristics of the domestic environments have effect on the colonization of sand flies. Increment of the supportive domestic characters intensifies the colonization of sand flies.
An Evaluation on Factors Influencing Venom Yield in Spectacled Cobra (Naja naja) in Sri Lanka
(Faculty of Graduate Studies, University of Kelaniya, 2015) Dissanayake, D.S.B.; Rajapakse, R.P.V.J.; Kularatne, S.A.M.
Snake venom contains medically important toxic proteins. Proteroglyphous snakes of the family Elapidae: Naja naja is the only recognized species of cobra in Sri Lanka and is responsible for a considerable number of envenomation and deaths due to snake bites. The dose of antivenin depends upon the amount of venom inflicted by the snake and the kinetics of venom distribution in the whole body. Although several studies have been conducted regarding this subject, the amount of venom ejecting per bite is still under investigation. The current study investigated whether the body size, sex and other morphological characteristics of N. naja have any influence on venom yield when milked manually. For milking, small-sterilized beakers that are tightly covered with parafilms layers were used. The head of each milking snake was held and venom was extracted to the prepared beakers by applying a gentle pressure to the venom glands. After that, the volume of wet venom of each snake was measured using graduated pipets and these volumes were used for statistical analysis. N. naja The average wet venom volume in 40 adult cobra (mean total length 1698 ± 161mm; mean body weight 1466 ± 287g) ranges from 200-1500μl (mean 485.15 ± 178.9μl) and 10 juvenile snakes (mean total length 632 ± 95mm and body weight 420 ± 93g) were 15-70μl. The venom yield positive correlated with the length and body weight of the snakes. Even though males hold slightly high volume of venom than females, this volume difference is not significant. In summary, we found that the venom yield is more correlated to the body size and total length than the sex and other morphological characters of snakes. Further studies are necessary to find out whether venom yield differs due to geographic variations or other related ecological factors.
In-vitro anti-cancer and cytotoxic properties of aqueous seaweed extracts on BHK and HeLa cell lines
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Ranahewa, T.H.; Premarathna, A.D.; Jayasooriya, L.J.P.A.P.; Wijesundara, R.R.M.K.K.; Rajapakse, R.P.V.J.
Cancer is a major health problem all over the world. Seaweeds and its active compounds have shown their potent cytotoxicity against cancer cells opening new sights for the production of new therapeutics. This study was performed to determine the cytotoxic effect and anti-cancer activity of aqueous extracts of selected Sri Lankan seaweed species on cancer (HeLa) and normal (Baby Hamster Kidney fibroblasts, BHK) cell lines. In addition, seaweed species with potent anticancer effect against cancer cell line was investigated. Samples of Ulva faciata (SW 01), Caulerpa racemosa (SW 02), Gracilaria corticata (SW 03), Sargassum illicifolium (SW 15) and Jania adhaereus (SW 26) were collected from Northern, Southern and North Western coastal sites of Sri Lanka. Aqueous extracts of seaweeds were prepared by soaking dried, powdered seaweed samples in distilled water through a modified method. Cells were cultured in a 96-well plate in Roswell Park Memorial Institute (RPMI 1640) medium and after 24-hour incubation, cells were treated with different seaweed extracts. Tetrazolium (MTT) colorimetric assay (in-vitro) was carried out after 24-hour incubation to determine cytotoxicity and anticancer effects. Viability percentages and growth inhibition rates for both cell types and with controls were compared. It was found that the seaweed extracts from different species showed significantly variable responses against cancer and normal cell lines. All seaweed extracts showed significant cytotoxic effect on cancer (HeLa) cells.
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.
Leishmaniasis: a vector- born disease in Sri Lanka: past, current and future
(Gloria Scientiam – Golden Jubilee Commemorative Volume, Faculty of Science, University of Kelaniya, 2017) Ganehiarachchi, G.A.S.M; Nayakarathna, N.M.N.G.; Rajapakse, R.P.V.J.
Leishmaniasis is caused by a protozoan parasite Leishmania species and is transmitted to humans by the bite of infected female phlebotomine (Diptera: Psychodidae) sand flies. There are three main forms of Leishmaniasis; Cutaneous Leishmaniasis, Muco-Cutaneous Leishmaniasis and Visceral Leishmaniasis. At present, Cutaneous Leishmaniasis is established in Sri Lanka. The parasite in this country is Leishmania donovani MON 37 and the prevalent vector is Phlebotomus argentipes. Environmental factors including temperature, humidity and rainfall influence the abundance and distribution of sand flies. Socio-economic conditions, population mobility, environmental and climate changes are the main risk factors of the spread of Leishmaniasis. Early detection of the disease and treatment, vector management and health education are the main control strategies for the control of the disease. It is a timely need to control the disease transmission before more virulent strains are established in the country. To resolve the epidemiology of Leishmaniasis further studies on the parasitic aspects and entomological studies of vector aspects are most important. Harmonizing with these biological phenomena, continuous surveillance, improving case detection programs at the community level and implementing management protocols and control activities are necessary to eliminate Leishmanisis in Sri Lanka
Molecular characterization of rickettsial agents in ticks (Acari: Ixodidae) from Sri Lanka
(Baltimore., 2022) Dasch, G.A.; Eremeeva, M.E.; Zambrano, M.L.; Premaratna, R.; Kularatne, S.A.M.; Rajapakse, R.P.V.J.
Because the majority of spotted fever group rickettsiae are transmitted to humans by tick bites, it is important to understand which ticks might play a role in transmission of rickettsial pathogens in Sri Lanka. The purpose of our study was to conduct molecular surveillance of 847 ticks collected in different locations in central Sri Lanka to determine which were infected with Rickettsia and Anaplasmataceae. Molecular methods were used to identify the ticks and the agents detected. Most ticks (Amblyomma, Haemaphysalis, and Rhipicephalus) were collected by flagging, and lower number was collected from dogs, cattle, pigs, a pangolin, and tortoises. Five spotted fever genotypes were identified: a Rickettsia africae-like agent in Amblyomma larvae, Rhipicephalus massiliae and a related genotype identified in association with the tropical type of Rhipicephalus sanguineus from dogs and Rhipicephalus haemaphysaloides from dogs and cattle, and Candidatus R. kellyi and another novel genotype (SL94) in R. haemaphysaloides. Twenty-three ticks were positive for Anaplasmataceae, including one Anaplasma and two Ehrlichia genotypes. Because the sequence database for both ticks and rickettsial agents from Sri Lanka and southern India is not extensive, additional molecular characterization of the tick species of Sri Lanka and their rickettsial agents is required to understand their pathogenic potential more completely. However, several of the agents we identified in this survey may well be pathogenic for humans and domestic animals, and should be considered as a part of epidemiological surveillance and patient management.
Molecular Phylogeography and Clinical manifestations of Russell’s viper (Daboia russelii) in Sri Lanka
(Faculty of Graduate Studies, University of Kelaniya, 2015) Dissanayake, D.A.; Dissanayake, D.S.B.; Bandara, K.B.A.T.; Kularatne, S.A.M.; Karunathilake, D.G.K.J.K.; Rajapakse, R.P.V.J.
The Russell‘s viper, Daboia russelii has a relict distribution over large areas of Indian Sub Continent, Taiwan and the Lesser Sunda islands. Russell‘s viper is distributed with varying densities and occurrence throughout many natural and modified habitats in Sri Lanka. Bite of this species is associated with a high incidence of morbidity and mortality in Sri Lanka. There is scanty of information available about Russell‘s viper in Sri Lanka. Thus, preliminary study was carried out using clinical data obtained from the twenty eight patients admitted due to Russell‘s viper bite in General Hospitals in the Gampaha District. Further, thirty five DNA samples were collected from the tail tip of specimens of the Russell‘s viper from Gampaha, Kandy, Rathnapura, Galle, Anuradhapura and Kurunagala districts for molecular phylogeny. Then fragment of mtDNA sequencing fragments of cytochrome b genes were amplified. PCR and products were subjected. DNA sequencing for molecular analysis using raxmlGUI software. Results revealed that the clinical features following Russell‘s viper envenomation are follows; local swelling 86%, local necrosis 7%, coagulopathy 75%, neurotoxicity 32%, nephrotoxicity 14% and cardiac effects 3%. Mortality of Russell‘s viper bites are caused by complications like renal failure, neurotoxicity, respiratory failure, disseminated intravascularcoagulation, heart failure and other cardiotoxic effects. Alignment of Sequences of Cytochrome-b gene by maximum likelihood analysis revealed that two strongly supported monophyletic clades corresponding to Sri Lanka and the Indian subcontinent. However, Sri Lankan Russell‘s viper was nested within the clade of Indian Russell‘s viper group. There was genetic divergence (2%) between the Indian clades and the Sri Lankan clade. However, these haplotypes do not show any geographically significant pattern. Thus, it could be suggested that Indian and Sri Lankan Russell‘s viper are genetically closely related and origin may be India or Sri Lanka. Further studies are being carried out on morphometric, molecular taxonomic and venomous differences in different geographic location within the Sri Lanka and Asian region.
Occurence of tick bits and serological evidence of exposure to rickettsioses among Sri Lankan military personnel
(International Society for Infectious Diseases, 2009) Premaratna, R.; Chandrasena, T.G.A.N.; Nawasiwatte, B.M.T.P.; Kulasiry, K.I.R.; Rajeev, S.; Bandara, K.B.K.R.G.W.; Rajapakse, R.P.V.J.; Kularatna, S.A.M.; de Silva, H.J.
Abstract Available
A Patient with spotted fever group rickettsiosis mimicking connective tissue disease
(Sri Lanka Medical Association, 2012) Premaratna, R.; Liyanaarachchi, E.W.; Rajapakse, R.P.V.J.; Bandara, N.K.B.K.R.G.W.; de Silva, H.J.
Progress report of Rickettsial disease diagnostic and research laboratory (RDDRL), Faculty of Medicine, University of Kelaniya
(Sri Lanka Medical Association, 2009) Premaratna, R.; Chandrasena, T.G.A.N.; Bandara, N.K.B.K.R.G.W.; Rajapakse, R.P.V.J.
INTRODUCTION: RDDRL was established at Faculty of Medicine, University of Kelaniya (FMUK) in June 2008 in collaboration with Centers for Disease Control and Prevention, Atlanta, Georgia, USA and Faculty of Veterinary Medicine, University of Peradeniya. OBJECTIVES: We present the contribution of RDDRL towards the diagnosis of ricketsioses over the 5 months since its inception. RESULTS: 84 acute serum samples were analysed [56 from Colombo North Teaching Hospital (CNTH), 4 from Teaching Hospital Jaffna (THJ), 7 from Base Hospital Kamburupitiya (BHK) 3 from Lady Ridgeway Hospital (LRH), 2 from Infectious Disease Hospital (IDH), 2 from Colombo South Teaching Hospital (CSTH), and 10 from the private sector hospitals (PVT)]. 48/84 (57%) had diagnostic titers; 31 (65%) for Rickettsia conorii (RC) and 17 (35%) for Orientia tsutsugamushi (OT). The total (%) positives for each hospital were; CNTH: 22/56 (39%), BHK: 7/7 (100%), Jaffna: 3/4 (75%), LRH: 1/3 (33%), IDH: 1/2 (50%), CSTH: 0/2(0%) and PVT: 8/10 (80%). The district total (ROOT); Gampaha: 33 (26:7), Matara: 7 (3:4), Jaffna: 3 (0:3), Puttlam: 5 (2:3). The mode (range) duration of febrile illness at the time of request was 14 (3-90) days and 6 samples were from severe complicated patients; 2-encephaiitis, 2-'Neuroleptic malignant syndrome', 1-muiti-organ failure and 1-severe gastroenteritis. CONCLUSIONS: Out of the clinically suspected patients, 57% were positive for rickettsiosis; 65% caused by R. conorii and 35% by O. tsutsugamushi. However, the request for serological diagnosis was made after a considerable delay in the majority of cases.
Rickettsioses presenting as major joint arthritis and erythema nodosum: description of four patients
(Springer International, 2009) Premaratna, R.; Chandrasena, T.G.A.N.; Rajapakse, R.P.V.J.; Eremeeva, M.E.; Dasch, G.A.; Bandara, N.K.B.K.R.G.W.; de Silva, H.J.
Erythema nodosum and aseptic arthritis are recognized associations of rickettsial infections. However, they usually present with a febrile illness rather than with severe arthritis. We report three patients who presented with incapacitating major joint arthritis and one who presented with severe spondyloarthropathy in addition to major joint arthritis due to serologically confirmed Orientia tsutsugamushi and Rickettsia conorii infections. All of them had erythema nodosum and low-grade fever. They had rapid clinical response to doxycycline.
Unusual pancytopenia secondary to haemophagocytosis syndrome in rickettsioses
(Oxford University Press, 2009) Premaratna, R.; Williams, H.S.A.; Chandrasena, T.G.A.N.; Rajapakse, R.P.V.J.; Kularatne, S.A.M.; de Silva, H.J.
We report two patients who presented with a long-lasting febrile illness associated with pancytopenia. Both of them had evidence of hypercellular marrow with haemophagocytosis. They were confirmed as having rickettsial infections by serology and had a rapid haematological recovery with anti-rickettsial antibiotics. We highlight the importance of considering rickettsial infections in patients with such clinical presentations, especially in areas where these infections are endemic or re-emerging. Empirical use of anti-rickettsial antibiotics in such situations could be beneficial, when facilities to diagnose rickettsial diseases are not readily available.