Browsing by Author "Mallawarachchi, C.H."

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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.
Human infection with sub-periodic Brugia spp. in Gampaha District, Sri Lanka: a threat to filariasis elimination status?
(BioMed Central, 2018) Mallawarachchi, C.H.; Chandrasena, T.G.A.N.; Premaratna, R.; Mallawarachchi, S.M.N.S.M.; de Silva, N.R.
BACKGROUND: Post-mass drug administration (MDA) surveillance during the lymphatic filariasis (LF) elimination program in Sri Lanka, revealed the re-emergence of brugian filariasis after four decades. This study was done with the objectives of investigating the epidemiology and age-specific vulnerability to infection. Surveillance was done using night blood smears (NBS) and the Brugia rapid test (BRT), to detect microfilaria (MF) and anti-Brugia IgG4 antibodies in blood samples collected from an age-stratified population enrolled from two high-risk study areas (SA)s, Pubudugama and Wedamulla in the Gampaha District. The periodicity of the re-emergent Brugia spp. was characterized by quantitative estimation of MF in blood collected periodically over 24 h using nucleopore-membrane filtration method. RESULTS: Of 994 participants [Pubudugama 467 (47.9%) and Wedamulla 527 (53%)] screened by NBS, two and zero cases were positive for MF at Pubudugama (MF rate, 0.43) and Wedamulla (MF rate, 0), respectively, with an overall MF rate of 0.2. Of the two MF positives, one participant had a W. bancrofti while the other had a Brugia spp. infection. Of 984 valid BRT test readings [Pubudugama (n = 461) and Wedamulla (n = 523)], two and seven were positive for anti-brugia antibodies by BRT at Pubudugama (antibody rate 0.43) and Wedamulla (antibody rate 1.34), respectively, with an overall antibody rate of 0.91. Both MF positives detected from SAs and two of three other Brugia spp. MF positives detected at routine surveillance by the National Anti-Filariasis Campaign (AFC) tested negative by the BRT. Association of Brugia spp. infections with age were not evident due to the low case numbers. MF was observed in the peripheral circulation throughout the day (subperiodic) with peak counts occurring at 21 h indicating nocturnal sub-periodicity. CONCLUSIONS: There is the low-level persistence of bancroftian filariasis and re-emergence of brugian filariasis in the Gampaha District, Sri Lanka. The periodicity pattern of the re-emergent Brugia spp. suggests a zoonotic origin, which causes concern as MDA may not be an effective strategy for control. The importance of continuing surveillance is emphasized in countries that have reached LF elimination targets to sustain programmatic gains.
An investigation of a new cutaneous leishmaniasis endemic area in Western Sri Lanka
(Oxford University Press, 2021) Mallawarachchi, C.H.; Chandrasena, N.; Wijerathna, T.; Dalpadado, R.; Mallawarachchi, M.S.M.N.S.; Gunarathna, D.G.A.M.; Gunathilaka, N.
BACKGROUND: The aim was to investigate an emerging focus of cutaneous leishmaniasis (CL) in Gampaha district, Western Sri Lanka. METHODS: Sociodemographics of CL patients in Mirigama, Gampaha district, were compared with controls using a structured questionnaire. Clinical data and geographic positioning system coordinates of patients were recorded. Sandflies collections were performed in four selected sites using indoor hand collection (162 units) and cattle-baited net traps (n=3). RESULTS: Of 73 patients (mean age 43.6 y; SD 20), 58.9% were males. Lesions consisted of nodules (52.1%) and ulcers (47.9%). Single lesions were seen in 69.9% of patients, while 30.1% had multiple lesions. Except for one mucosal lesion, all the others were cutaneous. Treatment consisted of sodium stibogluconate and cryotherapy (46.6%), sodium stibogluconate (45.2%) or cryotherapy (8.2%). Multiple lesions were more likely to receive combination therapy (p=0.013). The majority of those employed (81.1%; 27/33) were engaged in outdoor work. Male gender, low education attainment and poor disease awareness were significant risk factors for CL (p<0.05). Four households reported multiple cases. Phlebotomus argentipes was detected in all cattle-baited net traps and 35.3% of indoor hand collection units. CONCLUSIONS: CL is emerging in Gamapha district with Mirigama as the epicentre. Case distribution indicates local transmission, with P. argentipes as the probable vector. KEYWORDS: Sri Lanka; cutaneous leishmaniasis; emerging infectious diseases.
Lymphatic filariasis in the Southeast Asian region; status and control options.
(CABI Publishing, 2020) Chandrasena, T.G.A.N.; Premaratna, R.; Mallawarachchi, C.H.; Gunaratna, D.G.A.M.; de Silva, N.R.
ABSTRACT: The Global Program to Eliminate Lymphatic Filariasis (GPELF) was launched in year 2000 by the World Health Organization (WHO) with the goal set for elimination by 2020. Over half the global disease burden lies in the Southeast Asian region (SEAR). The preventive chemotherapy (PC) programme has been initiated in all the WHO SEAR member states with varying levels of progress. Maldives, Sri Lanka and Thailand have achieved the goal of elimination as a public health problem (EPHP) within the stipulated period with Bangladesh working towards validation in 2021. Both Sri Lanka and Thailand are continuing with post-validation surveillance combined with selective treatment, striving for zero transmission in-parallel with the morbidity management and disability prevention program (MMDP). Timor-Leste appears close to reaching critical transmission thresholds with 100% coverage and triple therapy in the last round of PC. Data on MMDP activities are insufficient to comment on reaching EPHP status. PC coverage and country reports indicate ongoing transmission in Nepal, Myanmar, Indonesia and India requiring further rounds of PC. The PELF has made considerable progress in the SEAR towards elimination but there still remain significant transmission and disease burden in the highly populated countries in SEAR.
Molecular characterization of a reemergent Brugia malayi parasite in Sri Lanka, suggestive of a novel strain
(Hindawi Pub. Co., 2021) Mallawarachchi, C.H.; Chandrasena, T.G.A.N.; Withanage, G.P.; Premaratna, R.; Mallawarachchi, S.M.N.S.M.; Gunawardene, Y.I.N.S.; Dasanayake, R.S.; Gunarathna, D.; de Silva, N.R.
ABSTRACT: Sri Lanka achieved elimination status for lymphatic filariasis in 2016; still, the disease remains a potential public health issue. The present study is aimed at identifying a subperiodic Brugia sp. parasite which has reemerged in Sri Lanka after four decades via molecular-based analysis. Polymerase chain reaction performed with pan-filarial primers specific for the internal transcribed spacer region-2 (ITS-2) of the rDNA of Brugia filarial parasites isolated from human, canine, and feline blood samples yielded a 615 bp band establishing the species identity as Brugia malayi. Comparison of the ITS2 sequences of the reemerged B. malayi isolates with GenBank sequences revealed a higher sequence homology with B. pahangi than B. malayi with similar phylogenetic evidence. However, the mean interspecies Kimura-2-parameter pairwise divergence between the generated Brugia sequences with B. malayi and B. pahangi was less than 3%. During the analysis of parsimony sites of the new ITS2 sequences, substitutions at A36T, A296G, T373A, and G482A made the sequences different from both B. pahangi and B. malayi suggesting the possibility of a new genetic variant or a hybrid strain of B. malayi and B. pahangi. Mosquito dissections and xenomonitoring identified M. uniformis and M. annulifera as vectors of this novel strain of B. malayi circulating among cats, dogs, and humans in Sri Lanka.
Ocular trematodiasis in children, Sri Lanka
(National Center for Infectious Diseases, 2023) Mallawarachchi, C.H.; Dissanayake, M.M.; Hendavitharana, S.R.; Senanayake, S.; Gunathilaka, N.; Chandrasena, T.G.A.N.; Yahathugoda, T.C.; Wickramasinghe, S.; de Silva, N.R.
Using histopathology and phylogenetic analysis of the internal transcribed spacer 2 gene, we found >2 distinct trematode species that caused ocular trematode infections in children in Sri Lanka. Collaborations between clinicians and parasitologists and community awareness of water-related contamination hazards will promote diagnosis, control, and prevention of ocular trematode infections.
A preliminary survey of filarial parasites in dogs and cats in Sri Lanka
(Public Library of Science, 2018) Mallawarachchi, C.H.; Chandrasena, T.G.A.N.; Wickramasinghe, S.; Premaratna, R.; Gunawardene, Y.I.N.S.; Mallawarachchi, N.S.M.S.M.; de Silva, N.R.
Human brugian filariasis has re-emerged in Sri Lanka after a quiescent period of four decades. This study investigated the prevalence of canine and feline filarial parasites in three localities with human sub-periodic brugian filariasis, in order to determine their potential reservoir status. All reachable dogs and cats, both stray and domestic, within a 350m radius of an index case of brugian filariasis in three locations (Madampe, Wattala and Weliweriya) were screened for microfilariae using Giemsa stained thick blood smears. A representative sample of canine and feline blood samples positive for Brugia spp. microfilariae by microscopy, from each of the three locations, were further analyzed by PCR with specific primers for internal transcribed spacer region 2 (ITS2) of the ribosomal DNA. A total of 250 dogs and 134 cats were screened. The overall microfilaraemia rates were high among both dogs (68.8%) and cats (47.8%). The prevalence of microfilaraemia was significantly higher among dogs than cats (p<0.05). Two filarial species were identified based on morphology of microfilariae: Dirofilaria (Nochtiella) repens (dogs, 54.4% and cats, 34.3%) and Brugia spp. (dogs, 51.6% and cats, 30.6%). PCR analysis of canine (n = 53) and feline (n = 24) samples elicited bands in the region of 615bp, which confirmed Brugia malayi infection. Co-infection with D.(N.) repens was detected by PCR with an additional band at 484bp, in 36 canine and 17 feline samples. Overall microfilaraemia rates of dogs (81.8%) and cats (75%) in Madampe (rural) were significantly higher than in urbanized Wattala (dogs, 62.4% and cats, 26.0%) (p<0.05). High rates of zoonotic filarial infections strongly implicate dogs and cats as potential reservoirs for human dirofilariasis and brugian filariasis in Sri Lanka.