Browsing by Author "Chandrasena, T.G.A.N."

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Acute hearing loss due to scrub typhus: a forgotten complication of a reemerging disease
(Oxford University Press, 2006) Premaratna, R.; Chandrasena, T.G.A.N.; Dassanayake, A.S.; Loftis, A.D.; Dasch, G.A.; de Silva, H.J.
We describe 6 patients with scrub typhus who presented with acute hearing loss, a forgotten complication of this reemerging disease. They were admitted with fever of 10-14 days' duration and had clinical evidence of deafness and pneumonitis. Five patients had eschars, which prompted the diagnosis of typhus fever and led to early institution of treatment. Deafness has been described as a clue to the diagnosis of scrub typhus; awareness of this symptom facilitated early diagnosis in 4 of 5 patients who recovered. Acute hearing loss or hearing impairment in a febrile patient should arouse strong suspicion of scrub typhus.
Acute hearing loss in febrile patients: a predictor of scrub typhus
(Sri Lanka Medical Association, 2005) Premaratna, R.; Chandrasena, T.G.A.N.; Dassanayake, A.S.; Loftis, A.; Dasch, G.A.; de Silva, H.J.
INTRODUCTION: Rickettsial infections are re-emerging in Sri Lanka. Complications such as pneumonitis, myocarditis and encephalitis can occur late in the disease, and result in a high mortality. Early diagnosis reduces morbidity and mortality, but as laboratory facilities for definitive diagnosis are lacking, early diagnosis depends on clinical suspicion. Acute hearing loss which occurs in about 30% of patients has been recognised as a predictor of scrub typhus. METHODS: Six patients admitted to hospital with high fever and hearing impairment were further investigated. RESULTS: All were females with a mean age of 65 years (SD 2). The mean duration of fever at presentation was 12 days (SD 1), Hearing impairment was observe
Annotated checklist of chigger mites (Trombidiformes: Leeuwenhoekiidae, Trombiculidae and Walchiidae) in Sri Lanka
(Elsevier, 2022) Ashani, M.L.S.; Gunathilaka, P.A.D.H.N.; Premaratna, B.A.H.R.; Chandrasena, T.G.A.N.; Jacinavicius, F.C.; Silva, R.B.
Chigger mites (Leeuwenhoekiidae, Trombiculidae, and Walchiidae) are parasites of any terrestrial vertebrate. The present study updates the list of chigger mite (Trombiculidae, Leeuwenhoekiidae, and Walchiidae) species recorded from Sri Lanka along with taxonomic classification based on previous investigations since 1946 to date and our observations in western and southern parts of the country. This checklist listed 15 species in 9 genera within the three chigger families. For now, murid species were the host most sampledparasitized by chiggers in Sri Lanka. However, further studies are required to increase the diversity of chigger mites in Sri Lanka and probably the description of new species, which will be possible with morphological and molecular characterization.
Awareness of Rickettsial Infections (Typhus Fever) in a High Endemic Community in Hambantota District, Sri Lanka
(International Postgraduate Research Conference 2019, Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2019) Ashani, M.L.S.; Chandrasena, T.G.A.N.; Gunathilaka, P.A.G.N.; Premaratna, B.A.H.R.
Rickettsial infections are re-emerging in Sri Lanka with an average annual incidence of 1500 patients. Low awareness and the scarcity of proper diagnostic tools has resulted in delayed disease diagnosis and negligence towards the disease leading to extended morbidity in Sri Lanka. Community awareness of the disease is important for timely diagnosis and control. Hambantota district in Southern Province of Sri Lanka, which records the fourth highest incidence of typhus, was selected for the study. Households (n= 204) situated around index cases of typhus fevers were randomly selected for the survey. An interviewer-administered questionnaire was used to gather data on illness awareness (disease aetiology, symptoms, transmission, disease associations) by selecting a consenting representative from each household. Descriptive and inferential analysis of the data was carried out using SPSS IBM statistical software. Of the 204 interviewed, only one (0.5%) identified the illness as “typhus”. Majority identified the disease as “Peacock fever” (43.12%; n= 88) followed by “tick fever” (14.71%; n=30). It is interesting to note that 41.67% (n=85) of the households were not aware of the disease even though they are living in a disease endemic area. None were aware of the etiological agents of typhus fever. Among those with awareness, 65.55% (n=78), believed that infection was tick-borne and the vector ticks were harbored by peacocks. About 27.73% (n=33) believed that the transmission was directly from peacocks, followed by other birds (2.52%; n=3). Majority 82.35 %, (n=98) were unaware of symptomatology while only 1.77%, (n=14) recognized it only as a febrile illness and myalgia (4.20%; n=5). Of those who were aware, 73.95 %, (n=88) had received information through acquaintances, 25.21% (n=30) from health personnel and one through mass media. None were aware of preventive measures. The results of the present study highlight the lack of proper awareness of the disease condition, which may adversely impact on disease control efforts
Clearance of microfilaraemia and red blood cell glutathione peroxidase(GPX) levels in asymptomatic microfilaraemics after single dose and 14 days’ treatment with diethyl carbamazine citrate(DEC)
(Wiley, 2001) Premaratna, R.; Chandrasena, T.G.A.N.; Abeyewickreme, W.; de Silva, N.R.; Chandrasena, L.G.; de Silva, H.J.
Abstract Available
Clearance of microfilaraemia and red blood cell glutathione peroxidase(GPX) levels in asymptomatic microfilaraemics after single dose and 14 days’ treatment with diethyl carbamazine citrate(DEC)
(Sri Lanka Medical Association, 2001) Premaratna, R.; Chandrasena, T.G.A.N.; Abeyewickreme, W.; de Silva, N.R.; Chandrasena, L.G.; de Silva, H.J.
Abstract Available
Clinical Charasteristics of paediatric rickettsioses
(Sri Lanka Medical Association, 2013) Premaratna, R.; Karunasekara, K.A.W.; Fernando, M.A.M.; de Silva, L.; Chandrasena, T.G.A.N.; de Silva, H.J.
INTRODUCTION AND OBJECTIVES: Rickettsioses are re-emerging in Sri Lanka. Both children and adults are vulnerable to these infections. Data on paediatric rickettsioses in the country are sparse. Objectives were to study the clinical characteristics of paediatric rickettsioses based on data received by the Rickettsail Disease Diagnostic and Research Laboratory (RDDRL), Faculty of Medicine, University of Kelaniya, over the last two years. METHODS: All clinical and laboratory data of confirmed rickettsioses were analyzed. RESULTS: Out of 46 requests received by the RDDRL, 22 were positive for acute rickettsioses in diagnostic titres IFA-IgD>1:128 (all>256). Of the positives, 16 were positive for spotted fever group rickettsioses (SFG), 5 for scrub thypus (ST) and 1 for both. 4/5 ST had eschars. The mean age was 56.59 months. (43.9); the youngest affected was aged 5 months. Of the sample 12 (54.5%) were male. Fever was present in all; mean duration was 9.81 (4.5) days; fever intensity was 102.80F (1.03); frequency of spikers per day was 2.33 (0.67). clinical features were headache 12 (54.5%), body aches 9 (40.9%), joint pains 6 (27.3%), cough 14 (63.6%), shortness of breath 5 (22.7%), rash 14 (63.6%); macular popular rash 13, diarrhea 4 (18.2%), lymphadenopathy 7 (31.8%), palpable liver 4, palpable spleen 1. Total WBC 11.1x109/L (SD-4.8); neurophils-84.8% (SD-13.8) lymphocytes 40.5% (17.2). ESR 1st Hr 46.3mm (SD-26.7) CRP 42.1mg/dl (40.6) SGOT 51.2iu/L (32.1) SGPT 50.2iu/L (51.4). ECG was normal in all, Chest x-ray showed patchy shadows in 4. CONCLUSIONS: SFG rickettsioses were commoner than ST, among children living in the Gampaha and Kurunegale districts. Clinical features were similar to adults. Diagnostic investigations were requested late in the febrile illness.
Clinically helpful rickettsial disease diagnostic IgG titers in relation to duration of illness in an endemic setting in Sri Lanka
(Biomed Central, 2012) Premaratna, R.; Weerasinghe, S.; Ranaweera, A.; Chandrasena, T.G.A.N.; Bandara, N.W.; Dasch, G.A.; de Silva, H.J.
BACKGROUND: Although an initial IFA-IgG titer greater or equal to 1/64 or 1/128 is considered positive in presumptive diagnosis, in clinical practice in an endemic setting for rickettsioses in Sri Lanka, some patients with IFA-IgG titer of 1/128 for either spotted fever group (SFG) or scrub typhus (ST) did not respond to treatment. FINDINGS: To determine a clinically helpful diagnostic algorithm, IFA-IgG results of serologically confirmed treatment responders were analyzed in relation to duration of illness at sampling. Of 146 suspected SFG, 3 responders of 25 patients had titers ≤1/128 with < 7 days of illness while all 9 with titers ≥1/256 responded (false negative with 1/256 cutoff was 12%, false positive was 0%). For illness > 7 days, the false negative and positive rates were 4.3% (3/59) and 11.3% (6/53). Of 115 suspected ST, false negative and positive rates with ≥1/256 cutoff at <7 days of illness were 14.2% (2/14) and 0% (0/8) respectively while > 7 days, false negative and positive rates were 2% (1/51) and 0% (0/42). CONCLUSIONS: For clinical decision making, duration of illness at sampling is important in interpreting serology results in an endemic setting. If sample is obtained ≤7 day of illness, an IgG titer of ≤1/128 requires a follow up sample in the diagnosis and > 7 days of illness, a single ≥1/256 titer is diagnostic for all ST and 90% of SFG.
Comparison of clinical and laboratory parameters between Rickettsiosis positive and negative children
(Sri Lanka Medical Association, 2013) Premaratna, R.; Karunasekara, K.A.W.; Fernando, M.A.M.; de Silva, L.; Chandrasena, T.G.A.N.; de Silva, H.J.; Miththinda, J.K.N.D.; Mufeena, M.N.F.; Madeena, K.S.K.; Bandara, N.K.B.K.R.G.W.
INTRODUCTION AND OBJECTIVES: Identification of clinical or biochemical parameters that differentiate rickettsioses from other fevers would help in clinical practice to reduce morbidity and mortality associated with childhood rickettsioses. METHODS: Clinical and laboratory parameters of 22 confirmed paediatric rickettsioses (SFG-16/22, ST-5/22, Mixed-1) were compared with those of 24 with fever who were negative for rickettsioses, based on data received by the Rickettsial Disease Diagnostic and Research Laboratory (RDDRL), Faculty of Medicine, University ofKelaniya. Results: Comparisons of clinical and laboratory parameters between rickettsioses vs non-rickettsioses were mean(SD); age in months 56.59 (43.9) vs 78.13 (42.08) (p=0.1); fever duration 9.81 days (4.5) vslO.68 days (8.79) (p-0.68); fever intensity 102.80F (1.03) vs 102.440F (1.23) (p=0.4); fever spikes per day 2.33 (0.67) vs 2.68 (0.75) (p=0.186); headache 12/22 vs 11/24 (p=0.64); body-aches 9/22 vs 9/24 (p-0.52); pain in arms and legs 6/9 vs 7/9 (p=0.5); joint pains 6/22 vs 7/24 (p=O.S9); cough 14/22 vs 9/24 (p=0.0*7); shortness of breath 5/22 vs 2/24 (p=0.19); eschar (all ST) 4/22 vs 0/24 (p=0.02); rash 14/22 vs 14/24 (p=0.69); maculo-papular rash!3/14 vs 12/14 (p=0.91); diarrhoea 4/22 vs 4/24 (p-0.89); lymphadenopathy 7/22 vs 8/24 (p=0.913); spleenl/22 vs 5/24 (p=0.18); total WBC 11.U109/L (4.8) vs 9.8xl09/L (4.8) (p=0.36); N-84.8% (13.8) vs 5.4(2) (p=0.29); ESR IstHr 46.3mm (26.7) vs 81.8mm (10.2) (p=0.37); CRP 42.1mg/dl vs 56.7mg/dl (6.7) (p=0.46); SCOT 51.2iu/L (32.1) vs 248.7iu/L (678) (p=0.43); SGPT 50.2iu/L (51.4) vs 170.7iu/L (404) (p=0.44). CONCLUSIONS: In paediatric patients, no clinical or biochemical parameter could differentiate rickettsioses from other aetiologies. Presence of eschars would help to diagnose scrub typhus. However laboratory confirmation is needed to differentiate SFG from other fevers.
Comparison of methods for diagnosis of bancroftian filariasis
(Sri Lanka Medical Association, 2000) Chandrasena, T.G.A.N.; Premaratna, B.A.H.R.; Abeyewickreme, W.; de Silva, N.R.
OBJECTIVE: Evaluate a rapid format immuno-chromatographic card test (ICT Diagnostics, Australia) in the diagnosis of bancroftian filariasis. METHOD: Thick night blood films (TBF), Nuclepore membrane filtration (NMF) and ICT were performed on venous blood collected from 226 individuals selected from highly endemic localities in Colombo [n~153 (63%)] and Gampaha [n=73 (32.3%)] districts. Blood was collected between 20.00 and 23.00 hours. 60ul of non-heparinised blood, 1ml and lOOpl of heparinised blood were used in TBF, NMF and ICT tests respectively. A self-administered questionnaire (expert validated) was used to screen for clinical manifestations. RESULTS: The mean age of the study population was 34-8yrs (range 14-76, SD 16.78); the male: female ratio was 98: 128. NMF was positive in 66/226 (29%), with a mean microfilariae count of 343/ml (range 9-1782, SD 422). All 66 were positive by ICT (sensitivity = 100%) but only 63 by TBF (sen.sitivity=95%). 59/226 (26.1%) had one or more filariasis specific symptoms (lymphoedema, hydrocoele, lymphadenitis, lymphangitis, fever, night cough and red spots). Of the 59, 25 (42.3%) were positive by the ICT, 24 (40.6%) were positive by NMF. The other 34 were negative in both tests. Out of the 166 asymptomatics, 42 were positive in both NMF and ICT, but there were 13 more positives with ICT. CONCLUSIONS: ICT card test was more sensitive in detecting microfilaria compared to venous thick night blood film. Both ICT and NMF were positive in only in about 40% of individuals with symptoms suggestive of filariasis.
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.
A descriptive study of 63 patients with rickettsial infections: reasons for delay in the diagnosis
(Sri Lanka Medical Association, 2008) Premaratna, R.; Chandrasena, T.G.A.N.; Bailey, M.S.; Loftis, A.D.; Dasch, G.A.; de Silva, H.J.
BACKGROUND: Most patients with rickettsial infections present to hospital as cases of "febrile illness of unknown origin". The delay in diagnosis may result in severe complications. Objectives: To determine reasons for the delay in diagnosis of rickettsial infections. DESIGN, SETTING AND METHODS: Patients admitted to the University Medical Unit, Colombo North Teaching Hospital, Ragama from November 2004 and diagnosed as having rickettsial infections and junior medical staff (JMS) were interviewed retrospectively to find possible reasons for delay in diagnosis. RESULTS: 63 patients [31 males; mean age 36 years (SD:12.2)] were recruited. (39 and 24 were later confirmed for Orientia tsutsugamushi, R. conorii infection byiFA titre >1:128) The mean duration of illness on admission was 9 days (SD:2.2). Clinical features on admission were fever 63(100%), headache 56(89%), lymphadenopathy 42(67%), eschar 42(67%), rash 12(19%), hepatomegaly 22(34%), splenomegaly 17(26%), deafness 6(9%), and tinnitus 8(12%). All 49 patients who could recall pre¬admission medication said they had not been given anti-rickettsial antibiotics. Interview of JMS (after-admission) showed that rickettsial infections were not considered in the differential diagnosis of 38(60%) patients. The other 25 were examined for an eschar: missed in 10(40%), detected in 9(36%) but not interpreted correctly in 7 of the 9 (63%). Rash was detected in all 12 patients who had it, but diagnosis was not considered in 10(83%). CONCLUSION: The main reasons for the delay in diagnosis seem to be lack of awareness of the high prevalence of rickettsial infections and poor knowledge of clinical features among junior medical staff.
Detection of a case of Brugian Filariasis from Anuradhapura, a non-endemic district of Sri Lanka
(Sri Lanka Medical Association, 2018) Mallawarachchi, C.H.; Gunaratne, I.E.; Ekanayaka, G.M.G.A.C.; Mallawarachchi, S.M.N.S.M.; Chandrasena, T.G.A.N.; Mendis, D.; de Silva, N.R.
INTRODUCTION AND OBJECTIVES: In 2016, the WHO declared that lymphatic filariasis was no longer a public health problem in Sri Lanka. However low-grade persistence of bancroftian filariasis continues in all three endemic provinces, while brugian filariasis has re-emerged. The periodicity pattern of the re-emerged Brugia spp. suggests zoonotic origin. A canine survey done in the district of Anuradhapura found a moderately high prevalence (28.2%) of B. malayi infections in the Thirappane MOH area. Objective of the study was to investigate the threat of zoonotic B.malayi infections to humans in the Thirappane MOH area. METHODS: A cross sectional survey was done among all consenting residents of three randomly selected areas representing the three PHI areas of the Thirappane MOH. Residents were screened between 8.00 pm and 12.00 pm using night blood smears (NBS) and Brugia rapid test (BRT) for presence of anti-Brugia IgG4 antibodies. BRT was done selectively. Ethical and administrative clearance was obtained prior to the survey. RESULTS: A total of 752 individuals were screened by NBS; 176 of them were also screened by BRT. 193, 208 and 351 NBSs were done respectively in Thirappane, Galkulama and Mooriyankadawala PHI areas. One individual, a 25-year-old long-term resident of Mooriyankadawala PHI area was positive for Brugia spp. microfilariae by NBS and by BRT. The microfilariae exhibited nocturnal sub-periodicity. CONCLUSION: Transmission of brugian filariasis appears to occur even outside the traditional endemic belt. The presence of canine reservoirs of infection and water bodies with aquatic vegetation probably favour transmission by Mansonia spp. vector mosquitoes in the study area.
Determination of appropriate positioning of the ovitraps for dengue mosquito surveillance
(Faculty of Graduate Studies, University of Kelaniya, 2015) Wijegunawardana, N.D.A.D.; Gunawardene, Y.I.N.S.; Chandrasena, T.G.A.N.; Dassanayake, R.S.; Gunathilaka, P.A.D.H.N.; Abeyewickreme, W.
Three months ovitrap survey was conducted to assess the suitable position in placing the ovitraps for dengue vector mosquito surveillance and this study was initiated due to loss of valuable data from our previous studies as a result of physical damage of the ground kept ovitarps. Thirty four households in the Ragama Medical Officer of Health area in Gampaha District were selected to conduct the ovitrap survey during the period of May to July, 2015 to select the most appropriate positioning of the ovitrap. The conventional black plastic ovitraps (3.2x 2.7 cm) were used in this purpose to collect aquatic stages of Aedes mosquitoes while placing plywood paddle (4 x 0.5 cm) over the upper rim of each coded ovitrap. A total of 136 ovitraps were used in the study site providing four ovitraps (2 each indoor & outdoor) for each house while one of the ovitraps of indoor and outdoor being hung and other being kept on the ground. In positioning ovitraps, the outdoor ones were kept 3m away from the house while leaving indoor ovitraps in the living room in close proximity to racks/hanging clothes or partially shaded places. Following collection of samples at each week, ovitraps were washed thoroughly, refilled with new water and a new paddle, and corresponding data were recorded and analyzed. These analyses revealed that number of larvae and the number of Aedes mosquito eggs present in the two different ovitrap positions (Ground kept vs Hung) were not significantly different; in spite of significant difference (P=0.001) between the outside and inside placements. Further, significantly higher values were observed for both number of mosquito eggs and larvae present in each ovitrap kept outside (60 and 13 respectively) than those placed inside (32 and 3 respectively). Furthermore, slightly higher values were observed for hung ovitraps (49 and 9 respectively) than ones kept on the ground (43 and 7 respectively). Finally, ovitrap placed above the ground level was selected in continuing the routine ovitrap survey, as there was considerable reduction of mechanical damage to the latter thus facilitating continuous data collection.
The Diversity of Human Dirofilariasis in Western Sri Lanka
(Hindawi Pub. Co, 2019) Chandrasena, T.G.A.N.; Premaratna, R.; Mallawaarachchi, C.H.; Gunawardena, N.K.; Gunathilaka, P.A.D.H.N.; Abeyewickrama, W.Y.; de Silva, N.R.
BACKGROUND:Human dirofilariasis is an emerging zoonosis in many countries. Dirofilariasis caused by Dirofilaria repens may present with diverse clinical manifestations in humans due to aberrant localization of worm lesions causing diagnostic dilemmas. The aim of this retrospective study was to describe and update the demography and clinical spectrum of human dirofilariasis in western Sri Lanka. Nematode or nematode fragments isolated from excision biopsies that were confirmed as D. repens at the Department of Parasitology, Faculty of Medicine, University of Kelaniya, Sri Lanka, between 2012 and 2018 were included. Data on age, gender, and clinical details were obtained from case files. Identity of worms was established by morphometry and cuticle characteristics on wet-mount preparation. Specimens from unusual case presentations were further analyzed by PCR with specific primers for internal transcribed spacer region 2 (ITS2) of the ribosomal DNA. RESULTS:Sixteen nematode specimens isolated from subconjunctiva (n=2), subcutaneous (n=13) and intramuscular (n=1) locations were identified as D. repens by morphometry (average length 11.5 cm) and the characteristic longitudinal striations on cuticle visualized by microscopy. The age distribution of cases ranged from 1 to 65 years with a mean of 21.5. Females were more frequently affected (n=10, 62.5%) and worm locations were commonest in the orbital region (5/16) and scrotum (3/16). Imaging techniques were of use in detecting infections in deeper tissue levels. PCR analysis of DNA extracted from a worm in an intramuscular granuloma of the temporal region elicited the expected band at 484bp for D. repens. CONCLUSIONS: Human dirofilariasis is on an upward trend in incidence. Imaging techniques were of use in clinical diagnosis and molecular speciation in establishing the species identity in unusual case presentations. We suggest a more conservative approach in the management of human dirofilariasis and recommend a one health approach for control.
Diversity of Wolbachia infections in Sri Lankan mosquitoes with a new record of Wolbachia supergroup B infecting Aedes aegypti vector populations
(Nature Publishing Group, 2024) Wijegunawardana, N.D.A.D.; Gunawardene, Y.I.N.S; Abeyewickreme, W.; Chandrasena, T.G.A.N.; Thayanukul, P.; Kittayapong, P.
Wolbachia bacteria are common endosymbionts of insects and have recently been applied for controlling arboviral vectors, especially Aedes aegypti mosquito populations. However, several medically important mosquito species in Sri Lanka were present with limited information for the Wolbachia infection status. Therefore, the screening of Wolbachia in indigenous mosquitoes is required prior to a successful application of Wolbachia-based vector control strategy. In this study, screening of 78 mosquito species collected from various parts of the country revealed that 13 species were positive for Wolbachia infection, giving ~ 17% infection frequency of Wolbachia among the Sri Lankan mosquitoes. Twelve Wolbachia-positive mosquito species were selected for downstream Wolbachia strain genotyping using Multi Locus Sequencing Type (MLST), wsp gene, and 16S rRNA gene-based approaches. Results showed that these Wolbachia strains clustered together with the present Wolbachia phylogeny of world mosquito populations with some variations. Almost 90% of the mosquito populations were infected with supergroup B while the remaining were infected with supergroup A. A new record of Wolbachia supergroup B infection in Ae. aegypti, the main vectors of dengue, was highlighted. This finding was further confirmed by real-time qPCR, revealing Wolbachia density variations between Ae. aegypti and Ae. albopictus (p = 0.001), and between males and females (p < 0.05). The evidence of natural Wolbachia infections in Ae. aegypti populations in Sri Lanka is an extremely rare incident that has the potential to be used for arboviral vector control.
Effect of genotyping on the severity of rotavirus Gastroenteritis
(Sri Lanka College of Paediatricians, 2011) Chandrasena, T.G.A.N.; Rajindrajith, S.; Gunawardena, N.K.; Silva, G.M.K.S.; Pathmeswaran, A.; Kazuhiko, M.; Kamruddin, A.
INTRODUCTION: Rotavirus is the commonest cause of paediatric gastroenteritis. There remains a controversy regarding disease severity being related to rotavirus genotype G9. OBJECTIVE: Study the genotype related severity of rotavirus gastroenteritis. DESIGN, SETTING AND METHOD: All children under 5 years of age who were admitted with acute diarrhoea to North Colombo Teaching Hospital and submitted a sample of stool for analysis from April 2005 to October 2008 were selected for the study. Clinical information was collected regarding the study group. Acute diarrhoea was defined as passage of 3 times or more stools over a period of 24 hours. Stools were collected from cases with blood and mucus diarrhoea as well. The stool compliance rate was around 75-80%. Faecal specimens were tested and genotyped for rotavirus using the ELISA kit, Rotaclone® (Meridian Diagnostics, Cincinnati) and reverse transcription (RT) PCR respectively. Severity of gastroenteritis was assessed using the 20 point scoring system ofVesikariand Ruuska. RESULTS: The total number of stool specimens collected during the study period was 813 and of this 178 were positive for group A rotavirus; all the rotavirus positive stool specimens were genotyped. The two predominant VP7 genotypes were G9 (76; 42.7%) and Gl (35; 19.7%) followed by G2 (22; 12.4%), G3 (22; 12.4%), G12 (18; 10.1%) and G4 (4; 2.2%) respectively. The mean severity scores of, Gl, G2, G3, G4, G9 and G12 were 12,12,12,14,13 and 13, respectively. Comparison of clinical features between the two common G types, G9 and Gl revealed the following: duration of diarrhoea was longer among G9 (mean 4±2 days) than Gl (mean 2±1 day) and a higher percentage of cases were febrile and had vomiting in G9 (84.9 and 86.3 respectively) than Gl (76.7 and 65.5 respectively) infections (p>0.05). The rest of the clinical features were similar. The percentage with severe disease (score >14) was higher among the G9 (38.4) than among Gl (26.7) infections (p>0.05). CONCLUSION: Although rotavirus G9 genotype was associated with a more severe gastroenteritis than the common Gl genotype, this association was not significant (p>0.05).
Effects of antibiotics on filarial transmission
(Sri Lanka College of Microbiologists, 2003) Chandrasena, T.G.A.N.; Taylor, M.J.
INTRODUCTION: The symbiosis of filarial nematodes and intracellular Wolbachia bacteria has recently been exploited as a target for therapy of filariasis. OBJECTIVE: To study the effects of antibiotics on filarial transmission in-vitro. METHODS: Two groups of microfilariae (mf) of Brugia pahangi (cat filarial species) were maintained in culture and exposed to 10 µm) solutions of tetracycline and doxycycline respectively, for 48 hours. A control group of Mf was maintained for 48 hours with no added antibiotics except for those routinely included in the culture medium. Mf counts in cultures were determined at the onset of experiment (8000 mf/culture flask). Three groups of Aedes aegypti mosquitoes were artificially infected with the treated and untreated mf by membrane feeding technique (mf concentration; 2000 mf/ml of blood). Mosquito dissections were performed 2 hours and 15 days post-infection to assess mf intake and development in vector hosts. RESULTS: Mf intake was similar in the treated and the control groups {8,5 and 9 mf recovered in 4,3 and 3 mosquitoes from tetracycline(n=6), doxycycline(n=6) and control(n=6) groups respectively}. Mosquitoes fed on tetracycline treated B.pahangi (n=70) were completely free of L3 (infective larvae while in the doxycycline (n=71) and control groups (n=71) the percentage of infection was 1.4% (01 infective larva in 01 mosquito) and 24% (17 infective larvae in 13 mosquitoes) respectively. The infectivity of mosquitoes fed on antibiotic treated Mf was significantly reduced (P value < 0.001). CONCLUSIONS: Exposure of Mf of B.pahangi to physiological concentrations of anti-wolbachia antibiotics even for a brief duration significantly affects their transmission potential.
Etiology of fever of unknown origin in a selected group of Sri Lankan patients with prompt responses to Doxycycline
(Centers for disease control and Prevention, 2008) Dasch, G.A.; Premaratna, R.; Rajapakse, R.P.; Chandrasena, T.G.A.N.; Eremeeva, M.E.; de Silva, H.J.
BACKGROUND: Most patients with long duration of fever go undiagnosed in settings where diagnostic facilities are inadequate. Untreated rickettsial infections cause extended fevers; while both scrub typhus and tick typhus are re-emerging diseases in Sri Lanka, laboratory facilities to specifically diagnose rickettsial infections in Sri Lanka are not available. METHODS: We collected 2 ml venous blood from febrile patients who had no etiological diagnosis after 7 days of hospital admission, but who showed rapid clinical response to doxycycline, to verify whether they had experienced a rickettsial infection. Acute serum samples were analysed using IFA for rickettsial infections caused by Orientia tsutsugamushi, Rickettsia conorii and Rickettsia typhi. A positive IgG IFA titer >1:128 was used to define a probable case of rickettsial infection. RESULTS: 28 patients [15 males, mean age 32.5 (SD 9.2 yrs)] were studied. Mean duration of fever at admission was 6.1 days (SD 3.1). Two patients had features suggestive of encephalitis and two had erythema nodosum. Others had no specific clinical features. Routine investigations were inconclusive and blood cultures were negative. IgG-IFA titer of >128 was found in 10 for R. conorii, 6 for O. tsutsugamushi and 6 for both R. conorii and O. tsutsugamushi. None were positive for R. typhi. Six were negative for all tests. One patient with encephalitis and one with erythema nodosum had high titers for R. conorii. CONCLUSIONS: The majority of Sri Lankan patients with undiagnosed fever responding promptly to doxycycline had a rickettsial etiology. Patients with rickettsioses exhibit varied clinical presentations so greater use of doxycycline for patients with extended fevers in rickettsial-endemic settings with inadequate diagnostic facilities appears warranted. The high proportion of patients with tick typhus and antibodies against both spotted fever and scrub typhus rickettsiae was unexpected based on previous studies of patients from the same region who were confirmed to have scrub typhus by serology and by the presence of the classic eschar. It is unknown whether the etiology of tick typhus and vector(s) transmitting this agent on the Western lowland region of Sri Lanka are the same as those responsible for spotted fevers in the central hill country of Sri Lanka.
Evaluation of the effects of Aedes vector indices and climatic factors on dengueincidence in Gampaha District, Sri Lanka
(Hindawi Publishing Corporation, 2019) Wijegunawardana, N.D.A.D.; Gunawardene, Y.I.N.S.; Chandrasena, T.G.A.N.; Dassanayake, R.S.; Udayanga, N.W.B.A.L.; Abeyewickreme, W.
Constant monitoring of Aedes vector indices such as Aedes mosquito abundance and ovitrap data is important for the control of dengue epidemics. Therefore, the current study attempted to evaluate the effect of larval and climatic factors on the incidence of dengue outbreaks in the Gampaha district. Based on the distribution of previously reported dengue cases, 34 households in Narangodapaluwa PHI area, Ragama, Sri Lanka, were selected randomly, and entomological surveillance was done fortnightly using adult mosquito catches and larval surveillance techniques for a period of two years. Further, weekly ovitrap surveillance was conducted for one year, by maintaining four ovitraps in a single house, two indoors and two outdoors at ground and at a height of 1.5-2 m. Based on the findings, larval indices, namely, Breteau index (BI), House index (HI), and Container index (CI), were calculated, along with the Ovitrap index (OI). The study area was positive for Ae. albopictus with an adult capturing range of 1~15/34 households. BI initially remained < 3%, which subsequently decreased up to 0. No significant difference in OI was found between the ovitraps placed at ground level and at a height of 1.5-2m (p>0.05), 95% level of confidence. The OI varied from 56.9% to 94.7% during the study period of 12 months, indicating two peaks at the monsoons. Statistics of one-way ANOVA revealed a significant difference in the monthly OI during the study period (p≤0.001) with two peaks representing the monsoonal rainfall patterns. Pearson's correlation analysis revealed that the association between dengue cases and larval indices (BI, CI, HI, and OI) and meteorological parameters was not significant (p<0.05). Migration of mosquitoes and patients could be considered as possible factors affecting the absence of a significant relationship.