Circulating dengue virus serotypes and vertical transmission in Aedes larvae during outbreak and inter-outbreak seasons in a high dengue risk area of Sri Lanka.

BACKGROUND: Spatial and temporal changes in the dengue incidence are associated with multiple factors, such as climate, immunity among a population against dengue viruses (DENV), circulating DENV serotypes and vertical transmission (VT) of DENV in an area at a given time. The level of VT in a specific location has epidemiological implications in terms of viral maintenance in vectors. Identification of the circulating DENV serotypes in both patients and Aedes mosquito larvae in an area may be useful for the early detection of outbreaks. We report here the results of a prospective descriptive study that was conducted to detect the levels of VT in Aedes mosquito larvae and circulating DENV serotypes in patients and Aedes mosquito larvae from December 2015 to March 2017 in an area of Sri Lanka at high risk for dengue. METHODS: A total of 200 patients with clinically suspected dengue who had been admitted to a tertiary care hospital during a dengue outbreak (3 study periods: December 2015-January 2016, June-August 2016, December 2016-January 2017) and in the inter-outbreak periods (February-May 2016 and September-November 2016) were investigated. Blood samples were drawn from the study participants to test for DENV. The houses of the study participants were visited within 7 days of admission to the hospital, and Aedes larvae were also collected within a radius of 400 m from the houses. The larvae were separately identified to species and then pooled according to each patient's identification number. Patients' sera and the Aedes larvae were tested to identify the infecting DENV serotypes using a reverse transcription PCR (RT-PCR) method. Levels of VT in Aedes mosquito larvae were also identified. RESULTS: All four DENV serotypes (DENV-1 to -4) were identified in the study area. In the early part of the study (December 2015-February 2016), DENV-3 was predominant and from April 2016 to March 2017, DENV-2 became the most predominant type. Four cases of DENV co-infections were noted during the study period in patients. Interestingly, all four DENV serotypes were detected in Aedes albopictus larvae, which was the prominent immature vectorial form identified throughout the study period in the area, showing 9.8% VT of DENV. With the exception of DENV-4, the other three DENV serotypes were identified in Aedes aegypti larvae with a VT of 8.1%. CONCLUSION: Comparatively high rates of VT of DENV was detected in Ae. albopictus and Ae. aegypti larvae. A shift in the predominant DENV serotype with simultaneous circulation of all four DENV serotypes was identified in the study area from December 2015 to March 2017.

Perceived social and built environment associations of leisure-time physical activity among adults in Sri Lanka.

OBJECTIVE: Although perceived neighbourhood environment is considered a predictor of leisure-time physical activity (LTPA), evidence for this is limited in South Asia. Thus, the aim was to determine the association between neighbourhood social and built environment features in carrying out LTPA among adults in Colombo District, Sri Lanka. A cross-sectional study among 1320 adults was carried out using validated questionnaires for physical activity (PA) and built environment data collection. Multiple logistic regression analysis was conducted to assess the associations between environment characteristics and LTPA after adjusting for gender, age, employment status, income level and sector of residence. RESULTS: A total of 21.7% of adults participated in some LTPA. The commonest type of LTPA was walking; carried out by 14.5%. Moderate and vigorous activity at leisure was carried out by 10.3% and 3.9% respectively. Perceived social acceptance for PA was positively associated with LTPA. Out of the built environment characteristics perceived infrastructure for walking, and recreational facilities for PA were negatively associated with LTPA. Self-efficacy emerged as an important positive correlate of LTPA. The participants were positively influenced by the self-efficacy and perceived social environment which should be addressed when promoting LTPA.

A GIS based approach to neighbourhood physical environment and walking among adults in Colombo municipal council area, Sri Lanka.

BACKGROUND: Physical Activity (PA) promotes health and wellbeing and walking is one of the easiest and commonest way to incorporate activity into everyday life. This study examined the association between the objectively measured neighbourhood physical environment and walking among the adults in Colombo Municipal Council (CMC) area in Sri Lanka. METHODS: A cross sectional study was carried out and primary data collection carried out to assess walking, socio-demographic characteristics and geo location of residence. Secondary data was obtained to assess neighbourhood environment from existing spatially referenced data from the survey department of Sri Lanka. Geographic Information Systems (GIS) was used to calculate density measures (residential density, land use, connectivity and access) and distance measures, which were then correlated with walking. RESULTS: A sample consisted of 284 adults aged 29-59 years with a mean age of 40.6 (SD,10.9) years. The total mean minutes walked a week was 175.8 min with a standard deviation of 214.0. The mean and the standard deviations of walking per week for transportation and leisure were 158.4 (SD,196.6) and 17.5 (SD,70.1) respectively. Residential density measures, building foot print area, length of major roads, number of intersections, number of bus stops, and distance to nearest major roads showed significant moderate degree of correlations with total minutes of walked per week, (p < 0.001). These results were similar with walking for transportation. CONCLUSION: There is indication that neighbourhood features are associated with walking among the adults in the CMC area using secondary data on physical environment. This paves way for further exploration to understand the relationship between neighbourhood physical environment and walking which could be used for effective interventions to promote walking.

Using multiple methods to assess heavy metal pollution in an urban city.

Heavy metal pollution in urban cities is now an accepted fact. An understanding of the natural and anthropogenic contributions to heavy metal accumulation in these cities is necessary to develop strategies to mitigate their impacts, particularly on human health. Here, we used multiple records using geological and biological pollution indicators to assess the extent of pollution in the Colombo Metropolitan Region (CMR), Sri Lanka. Elemental concentrations of Cu, Zn, Ni and Pb were determined in four depositories: surface soil (90 samples), canal sediments and canal water (45 samples each) and vegetation (62 samples). These were mapped using GIS overlapping the road network to identify hotspots of heavy metals. While the surface soil, canal sediments and leaves of trees had higher and different amounts than background levels of heavy metals, canal water had low levels. Our results suggest that anthropogenic activities are the major source of heavy metals in an urban city, and unique natural factors, such as coastal conditions, terrain morphology and climate, combine and influence the distribution of these metals. We discuss the possible remediation of metal pollution and the necessity of a holistic multi-proxy approach to understand urban heavy metal contamination in a rapidly populating area.

Pattern of Physical Activity Among Sri Lankan Adults in the District of Colombo: A Cross-sectional Study.

Physical inactivity is a modifiable risk factor of many non-communicable diseases. The aim of this study was to assess the pattern of physical activity among Sri Lankan adults in the district of Colombo, Sri Lanka. The study was carried out among a sample of 1320 adults aged 20 to 59 years, selected using stratified, cluster sampling method. Physical activity was assessed using the long form of the International Physical Activity Questionnaire validated for Sri Lanka. The prevalence of sufficient physical activity was 82.0% (CI = 78.5-85.0) for males and 79.7% (CI = 76.5-82.6) for females. The odds of having sufficient activity were lower with increase in the level of urbanisation. Activity was achieved mainly through domestic and transport related activity. Only 21.7% carried out at least some activity for leisure. As Sri Lanka continues to urbanize, it is important to find strategies to increase the level of activity especially at leisure.

Development and validation of a tool to assess the physical and social environment associated with physical activity among adults in Sri Lanka.

BACKGROUND: Environmental characteristics are known to be associated with patterns of physical activity (PA). Although several validated tools exist, to measure the environment characteristics, these instruments are not necessarily suitable for application in all settings especially in a developing country. This study was carried out to develop and validate an instrument named the "Physical And Social Environment Scale--PASES" to assess the physical and social environmental factors associated with PA. This will enable identification of various physical and social environmental factors affecting PA in Sri Lanka, which will help in the development of more tailored intervention strategies for promoting higher PA levels in Sri Lanka. METHODS: The PASES was developed using a scientific approach of defining the construct, item generation, analysis of content of items and item reduction. Both qualitative and quantitative methods of key informant interviews, in-depth interviews and rating of the items generated by experts were conducted. A cross sectional survey among 180 adults was carried out to assess the factor structure through principal component analysis. Another cross sectional survey among a different group of 180 adults was carried out to assess the construct validity through confirmatory factor analysis. Reliability was assessed with test re-test reliability and internal consistency using Spearman r and Cronbach's alpha respectively. RESULTS: Thirty six items were selected after the expert ratings and were developed into interviewer administered questions. Exploration of factor structure of the 34 items which were factorable through principal component analysis with Quartimax rotation extracted 8 factors. The 34 item instrument was assessed for construct validity with confirmatory factor analysis which confirmed an 8 factor model (x2 = 339.9, GFI = 0.90). The identified factors were infrastructure for walking, aesthetics and facilities for cycling, vehicular traffic safety, access and connectivity, recreational facilities for PA, safety, social cohesion and social acceptance of PA with the two non-factorable factors, residential density and land use mix. The PASES also showed good test re-test reliability and a moderate level of internal consistency. CONCLUSIONS: The PASES is a valid and reliable tool which could be used to assess the physical and social environment associated with PA in Sri Lanka.