Demographical characterization of dengue infected patients in Akurana medial officer of health area, central Province of Sri Lanka.

Dengue has been recognized to be one of the major threats on the public health of many tropical countries including Sri Lanka. Controlling of the high rate of mortality caused by dengue, which remains without being altered regardless of the immense efforts and control strategies of the relevant authorities, has remained as a major challenge for the Sri Lankan health sector. Vulnerability assessment of communities to dengue infection is of higher importance in drafting and implementation of management plans to ensure effective management and controlling of dengue epidemics at the regional scale. Therefore, a statistic based analysis of the dengue patient characteristics was carried out to determine the susceptibility of population to dengue infection in Akurana Medical Officer of Health (MOH) area. Monthly records of reported dengue cases from 2010 to 2014 of the Akurana MOH division were collected. Normal Chi square test coupled with Paired-Chi square test was devised to investigate the impact of sex and age on the infection. MINITAB (version 14.12.0) software package was used for statistical analysis. In accordance with the results of the normal Chi square test, the Percentage Infected Male: Female Ratio (PIMFR) remains significantly altered throughout the period of study (p=0.001 61 (1.84%). However, according to the Paired-Chi square test, the vulnerability of age groups tend to shift significantly throughout the study period [>Χ2 (7, 0.95) = 14.067]. In conclusion males tend to indicate relatively high susceptibility to dengue. Age groups of 6 - 10, 11 - 20 and 21 - 30 could be recognized as highly vulnerable age groups in the community for dengue, while age group of >61 emerge as the least vulnerable age group for the infection of dengue in the Akurana MOH.Financial assistance from the National Research Council Funded Dengue Mega Project (NRC TO 14-04)

Impacts of Meteorological Parameters on the Abundance of Malaria Vector in Batticaloa District, Sri Lanka

Malaria is one of the most widespread Vector-BorneDiseases (VBDs) in the world causing serious losses to the health and economy. Out of many factors, meteorological parameters effects on malaria distribution significantly. Conditions including higher temperature, lower relative humidity and higher wind velocity are found to be affecting on mosquito oviposition, propagation and survival. In Sri Lanka, Batticaloawas considered as one of the malaria endemicdistrictsduring recentpast. Control and effective management in these areas had been difficult due to the lack of reliable data, human resource and the deterioration of the infrastructure caused by years of armed conflict. This study was carried out to identify the relationships exist between different malaria vectors and meteorological parameters in the district of Batticaloa.Entomological surveillance was carried out in three potential malaria sensitive areas (Vakarai, Vakaneri and Mandur) with a radius of 20km in the district of Batticaloa from April 2013 to July 2014. Adult mosquito samples were collected monthly by WHO standard method; Cattle Baited Net Collection (CBNT). Monthly meteorological parameters (T: mean temperature, RF: total rainfall, WS: wind speed and RH: Relative humidity) during the study period were also collected from the Department of Meteorology. Data were analyzed using SPSS version 15.0. Pearson’s correlation coefficients (r) at 0.05 probability were used to investigate the relationships among meteorological variables of the current month along with lag time period of two months and vector densities. The most dominant mosquito species in the area was An. subpictuswith a relative abundance of 31.56% while An. nigerrimuswas the second highest (21.22%). Significant relationships were only observed with RH and WS where, An. nigerrimus showed a negative moderate relationship (r=0.372; p=0.03) while An. subpictus showed a positive relationship (r= 0.375; p=0.029) with RH. In addition, An. subpictusalsoshowed a negative relationship with one month lagged time of WS. The findings of the study reveal that the relationships that exist between the vector and the meteorological parameters are complicated and unpredictable. Neither patterns nor consistencies were observed in these relationships. The adaptation of vector and the influence of other environmental and anthropological factors on the vector mosquito could be the reason for this behaviour.Keywords:Malaria, Vector, Abundance, Relative humidity, Wind spee

Spatial and seasonal analysis of human leptospirosis in the District of Gampaha, Sri Lanka

Leptospirosis is a zoonostic infectious disease, caused by a pathogenic species of the Genus Leptospira. In recent years, a markedly increased number of leptospirosis cases have been reported in the District of Gampaha, in the Western Province of Sri Lanka. Typically, the risk of the disease in the district is seasonal with a small spike occurs in March to May and a large spike occurs during October to December. Objectives of this study were to analyze spatial and seasonal patterns of human leptospirosis and to predict the leptospirosis epidemic trend in the District of Gampaha, Sri Lanka. All Divisional Secretariats (DS) of the district of Gampaha were selected for the study. Epidemiological data were obtained from the Regional Epidemiological Unit, Gampaha. The leptospirosis cases were georeferenced according to DS in where these cases were reported. The cumulative incidence and the fatality were calculated for each DS. Of the georeferenced data, highest mean (±S.E.) of number of leptospirosis cases (72.60 ±15.54) were observed from DS of Mirigama. The highest mean cumulative incidence (4.97±1.10) and case fatality rate (3.88±2.42) were observed from DS of Divulapitiya and Katana respectively. According to past 10 years data on leptospirosis, highest mean numbers of leptospirosis cases were reported in March (51.00±12.99) and November (56.80±8.27). A predictive model for clinically confirmed human leptospirosis was designed for the district by using TSA package of the statistical software R. This study provides an evidence base for reducing disease burden by improving the understanding of the dynamic patterns of the disease in the District of Gampaha, Sri Lanka.</p

Single Antigen Detects both Immunoglobulin M (IgM) and IgG Antibodies Elicited by All Four Dengue Virus Serotypes▿ †

The resurgence of dengue (DEN) virus infections in the last few decades coupled with the lack of a preventive vaccine and specific antiviral drugs has jointly contributed to making this a significant global public health problem. Currently, symptomatic supportive treatment and fluid replacement therapy are the only means available to minimize DEN-induced mortality. As the clinical symptoms associated with DEN virus infections are indistinguishable from those of many other viral, bacterial, and parasitic infections, specific diagnostic tests assume critical importance in the unequivocal identification of DEN virus infections. We have designed a novel chimeric antigen based on envelope domain III (EDIII), a critical antigenic region of the major structural protein of DEN viruses. We fused EDIIIs corresponding to each of the four DEN virus serotypes using pentaglycyl linkers, overexpressed the resultant tetravalent chimeric protein in Escherichia coli, and affinity purified it in high yields, obtaining ∼30 mg protein of >95% purity per liter of culture. We show that this tetravalent antigen could specifically recognize anti-DEN virus antibodies of both the immunoglobulin M (IgM) and IgG classes. Using a large panel of IgM antibody capture-enzyme-linked immunosorbent assay- and hemagglutination inhibition-confirmed DEN virus-infected and uninfected patient sera (n = 289), we demonstrate that this tetravalent antigen can function as a diagnostic tool of high sensitivity and specificity

Community mobilization and household level waste management for dengue vector control in Gampaha district of Sri Lanka; an intervention study

Introduction: Waste management through community mobilization to reduce breeding places at household level could be an effective and sustainable dengue vector control strategy in areas where vector breeding takes place in small discarded water containers. The objective of this study was to assess the validity of this assumption. Methods: An intervention study was conducted from February 2009 to February 2010 in the populous Gampaha District of Sri Lanka. Eight neighborhoods (clusters) with roughly 200 houses each were selected randomly from high and low dengue endemic areas; 4 of them were allocated to the intervention arm (2 in the high and 2 in the low endemicity areas) and in the same way 4 clusters to the control arm. A baseline household survey was conducted and entomological and sociological surveys were carried out simultaneously at baseline, at 3 months, at 9 months and at 15 months after the start of the intervention. The intervention programme in the treatment clusters consisted of building partnerships of local stakeholders, waste management at household level, the promotion of composting biodegradable household waste, raising awareness on the importance of solid waste management in dengue control and improving garbage collection with the assistance of local government authorities. Results: The intervention and control clusters were very similar and there were no significant differences in pupal and larval indices of Aedes mosquitoes. The establishment of partnerships among local authorities was well accepted and sustainable; the involvement of communities and households was successful. Waste management with the elimination of the most productive water container types (bowls, tins, bottles) led to a significant reduction of pupal indices as a proxy for adult vector densities. Conclusion: The coordination of local authorities along with increased household responsibility for targeted vector interventions (in our case solid waste management due to the type of preferred vector breeding places) is vital for effective and sustained dengue control

Predatory efficacy of five locally available copepods on Aedes larvae under laboratory settings: An approach towards bio-control of dengue in Sri Lanka.

Many countries are in search of more effective and sustainable methods for controlling dengue vectors, due to undeniable inefficiencies in chemical and mechanical vector control methods. Bio-control of vectors by copepods is an ideal method of using interactions in the natural ecosystem for vector management, with minimum consequences on the environment. Current study determined the predatory efficacy of five locally abundant copepod species on, Aedes larvae under laboratory conditions. Copepods were collected from the pre-identified locations within the districts of Gampaha and Kandy, and identified morphologically. Individual species of copepods were maintained as separate colonies with Paramecium culture and wheat grain as supplementary food. Five adult copepods of each species was introduced into separate containers with 200 larvae (1st instar) of Aedes aegypti. Number of larvae survived in containers were enumerated at 3 hour intervals within a duration of 24 hours. Each experiment was repeated five times. The same procedure was followed for Ae. albopictus. Significance in the variations among predation rates was evaluated with General Linear Modelling (GLM) followed by Tukey's pair-wise comparison in SPSS (version 23). Significant variations in predation rates of studied copepod species were reported (p<0.05), whereby M. leuckarti indicated the highest followed by M. scrassus, while C. languides indicated the lowest predatory efficacy. The effect of different Aedes larval species on the predation rates of copepods remained significant (p<0.05), even though the effect on predatory efficiency was not significant. Based on the findings, both M. leuckarti and M. scrassus, with the highest predatory efficiencies, could be recommended as potential candidates for biological controlling of Aedes vectors in Sri Lanka

Larval Indices of Vector Mosquitoes as Predictors of Dengue Epidemics: An Approach to Manage Dengue Outbreaks Based on Entomological Parameters in the Districts of Colombo and Kandy, Sri Lanka

Background. Early detection of dengue epidemics is a vital aspect in control programmes. Predictions based on larval indices of disease vectors are widely used in dengue control, with defined threshold values. However, there is no set threshold in Sri Lanka at the national or regional levels for Aedes larval indices. Therefore, the current study aimed at developing threshold values for vector indices in two dengue high-risk districts in Sri Lanka. Methods. Monthly vector indices (House Index [HI], Container Index [CI], Breteau Index for Aedes aegypti [BIagp], and Ae. albopictus [BIalb]), of ten selected dengue high-risk Medical Officer of Health (MOH) areas located in Colombo and Kandy districts, were collected from January 2010 to June 2019, along with monthly reported dengue cases. Receiver Operating Characteristic (ROC) curve analysis in SPSS (version 23) was used to assess the discriminative power of the larval indices in identifying dengue epidemics and to develop thresholds for the dengue epidemic management. Results. Only HI and BIagp denoted significant associations with dengue epidemics at lag periods of one and two months. Based on Ae. aegypti, average threshold values were defined for Colombo as Low Risk (2.4≤BIagp<3.8), Moderate Risk (3.8≤BIagp<5), High Risk (BIagp≥5), along with BIagp 2.9≤BIagp<4.2 (Low Risk), 4.2≤BIagp<5.3 (Moderate Risk), and BIagp≥5.3 (High Risk) for Kandy. Further, 5.5≤HI<8.9, 8.9≤HI<11.9, and HI≥11.9 were defined as Low Risk, Moderate Risk, and High Risk average thresholds for HI in Colombo, while 6.9≤HI<9.1 (Low Risk), 8.9≥HI<11.8 (Moderate Risk), and HI≥11.8 (High Risk) were defined for Kandy. Conclusions. The defined threshold values for Ae. aegypti and HI could be recommended as indicators for early detection of dengue epidemics and to drive vector management activities, with the objective of managing dengue epidemics with optimal usage of financial, technical, and human resources in Sri Lanka