Browsing by Author "Perera, V."

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    Detection of dengue viruses in vector mosquitoes collected from localities with reported dengue cases in the Gampaha District, 2008-2009
    (Sri Lanka Association for the Advancement of Science, 2010) Hapugoda, M.D.; Abeyewickreme, W.; Peris, I.; Warakagoda, S.; Perera, V.; Weerasinghe, I.
    Dengue is an important mosquito-borne flaviviral infection in Sri Lanka. Aedes aegypti is considered as the predominant vector of dengue and Ae. albopictus is considered as a subsidiary vector of dengue in Sri Lanka. Detection of dengue virus in these two vector species is important for control activities. Objective of this study was to examine transmission of dengue viruses by Ae. aegypti and Ae. albopictus mosquitoes in the field. Hundred dengue patients confirmed by both clinically and serologically were selected. Mosquito surveillance was conducted by visiting patient's premise within one week of notification of a case. A buffer zone covering 500 m radius in each confirmed patient's premise was surveyed. Larvae and adults were collected using standard larval surveillance techniques and a back-pack aspirator respectively. Adult and larvae were pooled (1-50 larvae/adult per pool). Single step single tube R -PCR assay followed by Semi-Nested-PCR agarose gel electrophoresis was performed. Ethical permission for this study was obtained from the Ethical Review Committee of the Faculty of Medicine, University of Kelaniya. Informed written consent was obtained from each patient for conducting mosquito surveillance at his/her premise. From 100 confirmed dengue case reported stations, 10% (10/100) and 60% (60/100) pools of Ae. aegypti and Ae. albopictus larvae were collected respectively. Adult mosquito collection showed 8% (8/100) and 30% (30/100) of Ae. aegypti andAe.albopictus respectively. These results showed high density of Ae. albopictus mosquitoes. Dengue 3 viral infection was detected in 1 and 7 pools of Ae. aegypti and Ae. albopictus respectively. Transmission of dengue serotype 3 virus by Ae. albopictus and high density of this species in selected areas were observed. Although Ae. aegypti is still the main vector initiating outbreaks and transmitting the disease in city centers, the possibility of Ae. albopictus playing a major role in this region should not be ignored.Theseadultmosquitoes may acquire dengue viruses through horizontal or vertical transmission. Alargenumber of mosquito pools needed to test for confirmation.Acknowledgements: Financial assistance from the WHO/SEARO (WHO/SEARO SN1167)and technical assistance from the IAEA (IAEA TC SRL TC 5/042) are gratefullyacknowledged.
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    Enteric pathogens of zoonotic concern in non-human primates in Sri Lanka
    (European Wildlife Disease Association (EWDA, 2016) Tegner, C.; Sunil-Chandra, N.P.; Ingrid, H.; Perera, V.; Wijesooriya, W.R.P.L.I.; Fahlman, A.
    Zoonotic disease is a two-way street where humans and other animals are interchanging pathogens. We investigated the occurrence of the potentially zoonotic Campylobacter spp., Salmonella spp. and group A rotaviruses in faecal samples from free-ranging toque macaques and tufted gray langurs in Sri Lanka. Samples were opportunistically collected from primate troops with close human contact at five sites. Standardized culturing was used to detect the bacteria and an ELISA-based dipstick test was used for detection of group A rotaviruses antigens. Genotyping was performed using pulse field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST) and the isolates' sensitivity to selected antibiotics was tested with VetMIC TM (National Veterinary Institute, Uppsala, Sweden) panels Camp EU, CLIN GN and GN-mo (version 4). All 98 samples tested negative for rotavirus. The 40 samples from gray langurs were also all negative for Campylobacter spp. and Salmonella spp. Of the 58 samples collected from toque macaques, C. jejuni was isolated from ten, C. coli from four and Salmonella enterica enterica subsp. Virchow from two of the samples. The fact that neither of the bacteria were isolated from tufted gray langur samples could reflect a true difference between the primate species. However, this should be interpreted in the light of a relatively small sample size. Resistance to ampicillin, ciprofloxacin, nalidixic acid and tetracycline was identified in four C. jejuni isolates, of which three were multidrug resistant. In addition, all C. jejuni showed undetectable MIC-values to colistin, while all C. coli were sensitive to the substance. All C. coli were resistant to ampicillin. The S. Virchow isolates were sensitive to all antibiotics tested for. Six strains of C. jejuni were identified using PFGE and MLST clonal complexes were assigned to all isolates. Sequence types were assigned to seven out of ten C. jejuni. The detection of antibiotic resistant zoonotic bacteria in free-ranging toque macaques with close human contact may have implications for both non-human primate conservation and public health in Sri Lanka and beyond