The Burden of Acute Febrile Illness Attributable to Dengue Virus Infection in Sri Lanka: A Single-Center 2-Year Prospective Cohort Study (2016-2019)

We performed a 2-year prospective cohort study to determine the incidence of dengue in Angoda, Colombo district, Sri Lanka (NCT02570152). The primary objective was to determine the incidence of acute febrile illness (AFI) because of laboratory confirmed dengue (LCD). Secondary objectives were to determine AFI incidence because of non-LCD, describe AFI symptoms, and estimate AFI incidence because of LCD by dengue virus (DENV)-type and age group. Participants from households with at least one minor and one adult (≤50 years) were enrolled and followed with scheduled weekly visits and, in case of AFI, unscheduled visits. Blood was collected for DENV detection at AFI visits, and symptoms recorded during the 7-day period following AFI onset. A total of 2,004 participants were enrolled (971 children, and 1,033 adults). A total of 55 LCD episodes were detected (overall incidence of 14.2 per 1,000 person-years). Incidence was the highest among children < 5 years (21.3 per 1,000 person-years) and 5–11 years (22.7 per 1,000 person-years), compared with adults ≥ 18 years (9.2 per 1,000 person-years). LCD was mostly (83.6%) caused by DENV-2 (n = 46), followed by DENV-1 (n = 6) and DENV-3 (n = 3). Common symptoms of LCD were headache, fatigue, myalgia, loss of appetite, and arthralgia. Incidence of AFI because of non-LCD was 47.3 per 1,000 person-years. In conclusion, this study reports the LCD incidence for a DENV-2 dominated epidemic that is comparable to the incidence of suspected dengue reported passively for 2017, one of the worst outbreaks in recent history.

Health related quality of life in chronic kidney disease; a descriptive study in a rural Sri Lankan community affected by chronic kidney disease

Introduction

The current epidemic of chronic kidney disease (CKD) in Sri Lanka is ascribed to the exponential increase in the number of CKD patients, which cannot be attributed to any known etiology (CKDu). The aim of this study is to describe the health related quality of life (HRQOL) and the associated factors among CKD/CKDu patients in a rural district in Sri Lanka.

Methods

A community based cross-sectional study included 1174 CKD/CKDu patients. Kidney Disease Quality of Life-Short Form was used to assess the HRQOL, while Centre for Epidemiologic Studies Depression Scale, General Health Questionnaire (GHQ) 12 and CKD Symptom Index – Sri Lanka were used to assess presence of depression, psychological distress and symptom burden respectively. Three summary scores; kidney disease (KDSC), physical (PCS) and mental (MCS) are derived from Kidney Disease Quality of Life-Short Form (KDQOL-SF™).

Results

Mean age of the study population was 58.3 years (standard deviation (SD) 10.7). Median KDSC (58.4; inter-quartile range (IQR) 54.2–63.4), was higher than the median scores of PCS (35.0; IQR 26.2–41.9) and MCS (58.4; IQR 54.2–63.4). Multiple linear regression revealed low income, advanced stages of CKD, symptom burden, being positive for depression and psychological distress were significantly associated with low HRQOL.

Conclusion

The HRQOL of the CKD patients in this rural Sri Lankan population was found to be poor. Superior socio-economic status, less physical and psychological symptom burden were found to be independently associated with better HRQOL. Periodical screening of the CKD patients for depression and psychological distress and measures to alleviate symptom burden seem to be important to improve the HRQOL of these patients.

Boosting of Mucosal Immunity After Fractional-Dose Inactivated Poliovirus Vaccine

Background

Inactivated poliovirus vaccine (IPV) boosts mucosal immunity in persons previously vaccinated with oral poliovirus vaccine (OPV). We assessed whether fractional-dose IPV (fIPV, 1/5th of full dose) administered intradermally also boosts mucosal immunity.

Methods

Children 10-12 years old were enrolled in Sri Lanka and randomized to receive one dose IPV, fIPV, or no IPV vaccine. One month later, they received OPV challenge. Blood was collected at enrolment and before challenge; stool was collected at 3, 7, and 14 days post-challenge. Sera were analysed for presence of poliovirus neutralizing antibodies; stool was analysed for poliovirus.

Results

We analysed 304/309 (98%) enrolled subjects. There were 16/97 (16%), 9/99 (9%), and 72/95 (76%) subjects excreting poliovirus after challenge in the IPV, fIPV and "No IPV Vaccine" study arms, respectively (P < .001 for comparison of IPV [or fIPV] vs "No IPV Vaccine"; P = .1 for comparisons of fIPV vs IPV). Relative decrease in excretion prevalence was 80% and 88% to IPV and fIPV, respectively, compared with the "No IPV Vaccine" control arm.

Conclusions

Single fIPV dose boosted mucosal immunity to a similar degree as single full dose of IPV. This finding provides further evidence in support of fIPV for poliovirus outbreak response at the time of IPV global supply shortage.

Clinical trials registration

Australia New Zealand Clinical Trial Registry ACTRN12616000124437p.

Prevalence and risk factors for impaired kidney function in the district of Anuradhapura, Sri Lanka: a cross-sectional population-representative survey in those at risk of chronic kidney disease of unknown aetiology

BACKGROUND

Over the last 20 years there have been reports of a form of chronic kidney disease of unknown cause (CKDu) affecting rural communities in the North Central Province of Sri Lanka. Valid prevalence estimates, using a standardised methodology, are needed to assess the burden of disease, assess secular trends, and perform international comparisons.

METHODS

We conducted a cross-sectional representative population survey in five study areas with different expected prevalences of CKDu. We used a proxy definition of CKDu involving a single measure of impaired kidney function (eGFR< 60 mL/min/1.7m², using the CKD-Epi formula) in the absence of hypertension, diabetes or heavy proteinuria.

RESULTS

A total of 4803 participants (88.7%) took part in the study and 202 (6.0%; 95% CI 5.2-6.8) had a low eGFR in the absence of hypertension, diabetes and heavy proteinuria and hence met the criteria for proxy CKDu. The proportion of males (11.2%; 95% CI 9.2-13.1) were triple than the females (3.7%; 95% CI 2.9-4.5). Advancing age and history of CKD among parents or siblings were risk factors for low GFR among both males and females while smoking was found to be a risk factor among males.

CONCLUSIONS

These data, collected using a standardised methodology demonstrate a high prevalence of impaired kidney function, not due to known causes of kidney disease, in the selected study areas of the Anuradhapura district of Sri Lanka. The aetiology of CKDu in Sri Lanka remains unclear and there is a need for longitudinal studies to describe the natural history and to better characterise risk factors for the decline in kidney function.

Prevalence and risk factors for impaired kidney function in the district of Anuradhapura, Sri Lanka: a cross-sectional population-representative survey in those at risk of chronic kidney disease of unknown aetiology

Background

Over the last 20 years there have been reports of a form of chronic kidney disease of unknown cause (CKDu) affecting rural communities in the North Central Province of Sri Lanka. Valid prevalence estimates, using a standardised methodology, are needed to assess the burden of disease, assess secular trends, and perform international comparisons.

Methods

We conducted a cross-sectional representative population survey in five study areas with different expected prevalences of CKDu. We used a proxy definition of CKDu involving a single measure of impaired kidney function (eGFR< 60 mL/min/1.7m², using the CKD-Epi formula) in the absence of hypertension, diabetes or heavy proteinuria.

Results

A total of 4803 participants (88.7%) took part in the study and 202 (6.0%; 95% CI 5.2–6.8) had a low eGFR in the absence of hypertension, diabetes and heavy proteinuria and hence met the criteria for proxy CKDu. The proportion of males (11.2%; 95% CI 9.2–13.1) were triple than the females (3.7%; 95% CI 2.9–4.5). Advancing age and history of CKD among parents or siblings were risk factors for low GFR among both males and females while smoking was found to be a risk factor among males.

Conclusions

These data, collected using a standardised methodology demonstrate a high prevalence of impaired kidney function, not due to known causes of kidney disease, in the selected study areas of the Anuradhapura district of Sri Lanka. The aetiology of CKDu in Sri Lanka remains unclear and there is a need for longitudinal studies to describe the natural history and to better characterise risk factors for the decline in kidney function.

Electronic supplementary material

The online version of this article (10.1186/s12889-019-7117-2) contains supplementary material, which is available to authorized users.

Evaluation of intensified dengue control measures with interrupted time series analysis in the Panadura Medical Officer of Health division in Sri Lanka: a case study and cost-effectiveness analysis

BACKGROUND

Dengue has become a major public health problem in Sri Lanka with a considerable economic burden. As a response, in June, 2014, the Ministry of Health initiated a proactive vector control programme in partnership with military and police forces, known as the Civil-Military Cooperation (CIMIC) programme, that was targeted at high-risk Medical Officer of Health (MOH) divisions in the country. Evaluating the effectiveness and cost-effectiveness of population-level interventions is essential to guide public health planning and resource allocation decisions, particularly in resource-limited health-care settings.

METHODS

Using an interrupted time series design with a non-linear extension, we evaluated the impact of vector control interventions from June 22, 2014, to Dec 29, 2016, in Panadura, a high-risk MOH division in Western Province, Sri Lanka. We used dengue notification and larval survey data to estimate the reduction in Breteau index and dengue incidence before and after the intervention using two separate models, adjusting for time-varying confounding variables (ie, rainfall, temperature, and the Oceanic Niño Index). We also assessed the cost and cost-effectiveness of the CIMIC programme from the perspective of the National Dengue Control Unit under the scenarios of different levels of hospitalisation of dengue cases (low [25%], medium [50%], and high [75%]) in terms of cost per disability-adjusted life-year averted (DALY).

FINDINGS

Vector control interventions had a significant impact on combined Breteau index (relative risk reduction 0·43, 95% CI 0·26 to 0·70) and on dengue incidence (0·43, 0·28 to 0·67), the latter becoming prominent 2 months after the intervention onset. The mean number of averted dengue cases was estimated at 2192 (95% CI 1741 to 2643), and the total cost of the CIMIC programme at 2016 US$271 615. Personnel costs accounted for about 89% of the total cost. In the base-case scenario of moderate level of hospitalisation, the CIMIC programme was cost-saving with a probability of 70% under both the lowest ($453) and highest ($1686) cost-effectiveness thresholds, resulting in a net saving of $20 247 (95% CI -57 266 to 97 790) and averting 176 DALYs (133 to 226), leading to a cost of -$98 (-497 to 395) per DALY averted. This was also the case for the scenario with high hospitalisation levels (cost per DALY averted -$512, 95% CI -872 to -115) but with a higher probability of 99%. In the scenario with low hospitalisation levels (cost per DALY averted $690, 143 to 1379), although the CIMIC programme was cost-ineffective at the lowest threshold with a probability of 77%, it was cost-effective at the highest threshold with a probability of 99%.

INTERPRETATION

This study suggests that communities affected by dengue can benefit from investments in vector control if interventions are implemented rigorously and coordinated well across sectors. By doing so, it is possible to reduce the disease and economic burden of dengue in endemic settings.

FUNDING

None.

National introduction of fractional-dose inactivated polio vaccine in Sri Lanka following the global "switch"

As part of the Polio eradication and endgame strategic plan 2013-2018 to achieve and sustain a polio-free world, the use of oral polio vaccine (OPV) must eventually be stopped. This process started in April 2016, with the worldwide, planned synchronized "switch", whereby use of OPV containing poliovirus type 2 ceased. Prior to the switch, in line with international guidance on risk mitigation, Sri Lanka had introduced a single full dose (0.5 mL intramuscularly) of inactivated polio vaccine (IPV) into routine immunization. However, the two global suppliers of World Health Organization (WHO)-prequalified IPV had significant challenges in scaling up production to meet the new demand, resulting in a global shortage in April 2016. The WHO Strategic Advisory Group of Experts on Immunization recommended that countries should consider a two-dose schedule of intradermal fractional IPV (fIPV). After rapid consideration of the programmatic cost and logistic implications, Sri Lanka was the first country to roll out this dose-sparing schedule nationwide. The country ensured smooth implementation of fIPV use, reaching out to all eligible infants, maintaining equity and sustaining the IPV vaccination. With expedited refresher training in intradermal vaccination, confident, well-trained and dedicated health-care staff, from the field up to provincial levels, worked together as a dedicated team. Health authorities at all levels reported that public acceptance of the additional injections of the new schedule was high. A post-introduction evaluation and an assessment of population-level immunity are under way.

Depression and psychological distress in patients with chronic renal failure: Prevalence and associated factors in a rural district in Sri Lanka

OBJECTIVE

Chronic Kidney Disease (CKD) is known to adversely affect mental health. The study was aimed at estimating the prevalence of depression and psychological distress and the associated factors among CKD patients living in Anuradhapura, a rural district in Sri Lanka.

METHOD

A community-based, cross-sectional study included a representative sample of 1174 CKD patients, drawn proportionately from all registered patients in all 19 Medical Officer of Health areas in the district of Anuradhapura. Trained paramedical staff visited the households and administered the locally validated Centre for Epidemiologic Studies Depression Scale and General Health Questionnaire-12 to screen for depression and psychological distress. Information related to associated factors was obtained through an interviewer-administered questionnaire.

RESULTS

A total of 1118 CKD patients participated, with a response rate of 95.2%. The mean age was 58.3 (SD 10.8) years. 62.7% of participants were males. The majority of participants was in CKD stage 4 (58.3%). The screening revealed that 75.0% (95% CI 72.5-77.5) of participants were psychologically distressed while 65.2% (95%CI 62.4-68.0) were found to be depressed. Multiple logistic regression analysis revealed advanced age, unemployment and poor health related quality of life contributed significantly to both depression and psychological distress.

CONCLUSION

Depression and psychological distress were significant in this community. Policymakers should consider the likely high prevalence of psychological distress and depression among CKD patients as well as the need for specific mental health services to confirm diagnosis and initiate effective management. Identified associated factors should be used to identify targeted preventative interventions.

Sustainable dengue prevention and control through a comprehensive integrated approach: the Sri Lankan perspective

Dengue is a leading public health problem in Sri Lanka. All 26 districts and all age groups are affected, with high disease transmission; the estimated average annual incidence is 175/100 000 population. Harnessing the World Health Organization Global strategy for dengue prevention and control, 2012-2020, Sri Lanka has pledged in its National Strategic Framework to achieve a mortality from dengue below 0.1% and to reduce morbidity by 50% (from the average of the last 5 years) by 2020. Turning points in the country's dengue-control programme have been the restructuring and restrategizing of the core functions; this has involved establishment of a separate dengue-control unit to coordinate integrated vector management, and creation of a presidential task force. There has been great progress in disease surveillance, clinical management and vector control. Enhanced real-time surveillance for early warning allows ample preparedness for an outbreak. National guidelines with enhanced diagnostics have significantly improved clinical management of dengue, reducing the case-fatality rate to 0.2%. Proactive integrated vector management, with multisector partnership, has created a positive vector-control environment; however, sustaining this momentum is a challenge. Robust surveillance, evidence-based clinical management, sustainable vector control and effective communication are key strategies that will be implemented to achieve set targets. Improved early detection and a standardized treatment protocol with enhanced diagnostics at all medical care institutions will lead to further reduction in mortality. Making the maximum effort to minimize outbreaks through sustainable vector control in the three dimensions of risk mapping, innovation and risk modification will enable a reduction in morbidity.

Analysis of Dengue Serotype 4 in Sri Lanka during the 2012-2013 Dengue Epidemic

The four serotypes of dengue virus (DENV-1, -2, -3, and -4) have had a rapidly expanding geographic range and are now endemic in over 100 tropical and subtropical countries. Sri Lanka has experienced periodic dengue outbreaks since the 1960s, but since 1989 epidemics have become progressively larger and associated with more severe disease. The dominant virus in the 2012 epidemic was DENV-1, but DENV-4 infections were also commonly observed. DENV-4 transmission was first documented in Sri Lanka when it was isolated from a traveler in 1978, but has been comparatively uncommon since dengue surveillance began in the early 1980s. To better understand the molecular epidemiology of DENV-4 infections in Sri Lanka, we conducted whole-genome sequencing on dengue patient samples from two different geographic locations. Phylogenetic analysis indicates that all sequenced DENV-4 strains belong to genotype 1 and are most closely related to DENV-4 viruses previously found in Sri Lanka and those recently found to be circulating in India and Pakistan.

Symptom burden in chronic kidney disease; a population based cross sectional study

Background

Physical and psychological symptoms are among main manifestations of Chronic Kidney Disease (CKD). This study aimed to assess the symptom burden and self-perceived severity of symptoms among CKD patients living in a district in Sri Lanka.

Method

A community based cross-sectional study included a sample of randomly selected 1174 CKD patients from all 19 Medical Officer of Health areas in the district of Anuradhapura. Trained para-medical staff visited the households and administered the locally validated questionnaire to assess the presence and severity of symptoms. The inquiry was on 25 symptoms in a 5 point Likert scale indicating the severity during the previous week. Symptom burden score was constructed by summing each symptom severity score which ranged from 0 to 125.

Results

A total of 1118 CKD patients participated with a response rate of 95.2%. The mean age was 58.3 (SD 10.8) years and 62.7% were males. A majority were in CKD stage 4 (58.3%). Bone/joint pain was the most experienced symptom (87.6%; 95%CI 85.6–89.5). Loss of libido was the most severe symptom. The median symptom burden score was 35.0 (IQR 20.0–50.0). Multiple linear regression revealed education up to Advanced Level (β −9.176), CKD stage V (β 3.373), being dialyzed (β 20.944), comorbidities (β 4.241) and being employed (β −9.176) to be significant predictors of symptom burden.

Conclusions

Patients in all stages of CKD experience high symptom burden warranting rigorous measures to relieve symptoms and to improve the well-being of CKD patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-017-0638-y) contains supplementary material, which is available to authorized users.

Validity and reliability of the Sri Lankan version of the kidney disease quality of life questionnaire (KDQOL-SF™)

BACKGROUND

The disabling symptoms, various food and fluid restrictions, restrictions to social life and stigma and taboos attached to Chronic Kidney Disease (CKD), have shown to pose a significant bearing on a patient's Quality of Life (QOL). In the present study the Kidney Disease QOL-Short Form (KDQOL-SF™) was culturally adapted, modified and translated into Sinhala and validity and reliability were assessed.

METHOD

The process to culturally adapt the Kidney Disease Specific Component (KDSC) of KDQOL-SF™ was carried out by the modified Delphi process with a group of experts. The construct validity of the KDSC was assessed using Exploratory Factor Analysis (EFA). Appraising construct validity of SF-36 component of KDQOL-SF™ was done by assessing the convergent and discriminant validity using the Multitrait-Multimethod Matrix technique (MTMM). Randomly selected 250 CKD patients attending the five renal clinics in Polonnauwa were used to assess the construct validity. To assess the test-retest reliability of the instrument, within a period of one week, 30 randomly selected study participants were visited at their households.

RESULTS

Two hundred and fifty adults with documented evidence of CKD participated. The EFA carried out using principal component factoring method and rotated by Varimax orthogonal method resulted in 14 factors with Eigen values ranging from 1.062-8.746. This 14 factor model explained 84.1% of total variance of the initial system. The communalities extracted for domains were all close to one. All the items were loaded to one or more domains with factor coefficients of more than 0.4, not requiring any of the items to be dropped. Few items which showed similarly high factor coefficients in more than one factor were assigned to a factor ensuring the pattern in the theoretical framework of the questionnaire based on expert opinion and vigorous analysis of literature. Convergent and divergent validity assessed using MTMM, revealed satisfactory construct validity. Cronbach's alpha of all domains of KDQOL-SF™ except for cognitive function and Social function, exceeded Nunnally's criteria of 0.7. The Intra class Correlation Coefficients (ICC) were more than 0.8 for all the domains, which indicated good test re-test reliability.

CONCLUSIONS

KDQOL-SF™ is a valid and reliable instrument which can be used to assess QOL of CKD patients in Sri Lanka.

Characteristics of and factors associated with dengue vector breeding sites in the City of Colombo, Sri Lanka

Introduction

Dengue has emerged as a major public health problem in Sri Lanka. Vector control at community level is a frequent and widespread strategy for dengue control. The aim of the study was to assess Aedes mosquito breeding sites and the prevention practices of community members in a heavily urbanized part of Colombo.

Methods

A cross-sectional entomological survey was conducted from April to June 2013 in 1469 premises located in a subdistrict of the City of Colombo. Types of breeding sites and, where found, their infestation with larvae or pupae were recorded. Furthermore, a questionnaire was administered to the occupants of these premises to record current practices of dengue vector control.

Results

The surveyed premises consisted of 1341 residential premises and 110 non-residential premises (11 schools, 99 work or public sites), 5 open lands, and 13 non-specified. In these 1469 premises, 15447 potential breeding sites suitable to host larvae of pupae were found; of these sites18.0% contained water. Among the 2775 potential breeding sites that contained water, 452 (16.3%) were positive for larvae and/or pupae. Schools were associated with the proportionally highest number of breeding sites; 85 out of 133 (63.9%) breeding sites were positive for larvae and/or pupae in schools compared with 338 out of 2288 (14.8%) in residential premises. The odds ratio (OR) for schools and work or public sites for being infested with larvae and/or pupae was 2.77 (95% CI 1.58, 4.86), when compared to residential premises. Occupants of 80.8% of the residential premises, 54.5% of the schools and 67.7% of the work or public sites reported using preventive measures. The main prevention practices were coverage of containers and elimination of mosquito breeding places. Occupants of residential premises were much more likely to practice preventive measures than were those of non-residential premises (OR 2.23; 1.49, 3.36).

Conclusion

Schools and working sites were associated with the highest numbers of breeding sites and lacked preventive measures for vector control. In addition to pursuing vector control measures at residential level, public health strategies should be expanded in schools and work places.

A Spatial Hierarchical Analysis of the Temporal Influences of the El Niño-Southern Oscillation and Weather on Dengue in Kalutara District, Sri Lanka

Dengue is the major public health burden in Sri Lanka. Kalutara is one of the highly affected districts. Understanding the drivers of dengue is vital in controlling and preventing the disease spread. This study focuses on quantifying the influence of weather variability on dengue incidence over 10 Medical Officer of Health (MOH) divisions of Kalutara district. Weekly weather variables and data on dengue notifications, measured at 10 MOH divisions in Kalutara from 2009 to 2013, were retrieved and analysed. Distributed lag non-linear model and hierarchical-analysis was used to estimate division specific and overall relationships between weather and dengue. We incorporated lag times up to 12 weeks and evaluated models based on the Akaike Information Criterion. Consistent exposure-response patterns between different geographical locations were observed for rainfall, showing increasing relative risk of dengue with increasing rainfall from 50 mm per week. The strongest association with dengue risk centred around 6 to 10 weeks following rainfalls of more than 300 mm per week. With increasing temperature, the overall relative risk of dengue increased steadily starting from a lag of 4 weeks. We found similarly a strong link between the Oceanic Niño Index to weather patterns in the district in Sri Lanka and to dengue at a longer latency time confirming these relationships. Part of the influences of rainfall and temperature can be seen as mediator in the causal pathway of the Ocean Niño Index, which may allow a longer lead time for early warning signals. Our findings describe a strong association between weather, El Niño-Southern Oscillation and dengue in Sri Lanka.

Costs of Dengue Control Activities and Hospitalizations in the Public Health Sector during an Epidemic Year in Urban Sri Lanka

Background

Reported as a public health problem since the 1960s in Sri Lanka, dengue has become a high priority disease for public health authorities. The Ministry of Health is responsible for controlling dengue and other disease outbreaks and associated health care. The involvement of large numbers of public health staff in dengue control activities year-round and the provision of free medical care to dengue patients at secondary care hospitals place a formidable financial burden on the public health sector.

Methods

We estimated the public sector costs of dengue control activities and the direct costs of hospitalizations in Colombo, the most heavily urbanized district in Sri Lanka, during the epidemic year of 2012 from the Ministry of Health’s perspective. The financial costs borne by public health agencies and hospitals are collected using cost extraction tools designed specifically for the study and analysed retrospectively using a combination of activity-based and gross costing approaches.

Results

The total cost of dengue control and reported hospitalizations was estimated at US$3.45 million (US$1.50 per capita) in Colombo district in 2012. Personnel costs accounted for the largest shares of the total costs of dengue control activities (79%) and hospitalizations (46%). The results indicated a per capita cost of US$0.42 for dengue control activities. The average costs per hospitalization ranged between US$216–609 for pediatric cases and between US$196–866 for adult cases according to disease severity and treatment setting.

Conclusions

This analysis is a first attempt to assess the economic burden of dengue response in the public health sector in Sri Lanka. Country-specific evidence is needed for setting public health priorities and deciding about the deployment of existing or new technologies. Our results suggest that dengue poses a major economic burden on the public health sector in Sri Lanka.

Dengue is a major public health problem affecting more than half of the world’s population living in tropical and subtropical regions of the world. The disease is estimated to place a heavy socio-economic burden on households, health care systems, and governments, particularly during outbreaks; however, country-specific reliable estimates of burden of disease and cost data are limited. This study estimated the public sector costs of dengue control activities and the direct costs of hospitalizations in Colombo district—the most heavily populated and urbanized district in Sri Lanka—during the epidemic year of 2012 from the Ministry of Health’s perspective. Results revealed that the Ministry’s cost of dengue control and hospitalizations totaled US$3.45 million (US$1.50 per capita), of which US$971,360 (US$0.42 per capita) was for dengue control activities. Personnel costs accounted for the largest shares of the costs of dengue control activities (79%) and of hospitalizations (46%). The results indicated a per capita cost of US$0.42 for dengue control activities. The average costs of hospitalization ranged between US$216–609 for pediatric cases and between US$196–866 for adult cases according to disease severity and treatment setting. These results suggest that dengue poses a major economic burden on the public health sector in Sri Lanka.

Achieving high seroprevalence against polioviruses in Sri Lanka--results from a serological survey, 2014

The immunization program in Sri Lanka consistently reaches >90% coverage with oral poliovirus vaccines (OPV), and no polio supplementary vaccination campaigns have been conducted since 2003. We evaluated serological protection against polioviruses in children. A cross-sectional community-based survey was performed in three districts of Sri Lanka (Colombo, Badulla, and Killinochi). Randomly selected children in four age groups (9–11 months, 3–4 years, 7–9 years, and 15 years) were tested for poliovirus neutralizing antibodies. All 400 enrolled children completed the study. The proportion of seropositive children for poliovirus Type 1 and Type 2 was >95% for all age groups; for poliovirus Type 3 it was 95%, 90%, 77%, and 75% in the respective age groups. The vaccination coverage in our sample based on vaccination cards or parental recall was >90% in all age groups. Most Sri Lankan children are serologically protected against polioviruses through routine immunization only. This seroprevalence survey provided baseline data prior to the anticipated addition of inactivated poliovirus vaccine (IPV) into the Sri Lankan immunization program and the switch from trivalent OPV (tOPV) to bivalent OPV (bOPV).

Impact of rubella vaccination on elimination of congenital rubella syndrome in Sri Lanka: progress and challenges

Rubella infection in pregnancy can lead to pathologies, including miscarriage, stillbirth and congenital rubella syndrome (CRS) in the neonate. Rubella vaccination can prevent all occurrences of CRS. In Sri Lanka, significant outbreaks of CRS occurred in 1994 and 1995, with 275 and 212 reported cases. In 1996, Sri Lanka introduced rubella vaccination for women aged 16-44 years, to stop CRS. Measles-rubella vaccine was introduced into the routine immunization schedule in 2001 and additional campaigns were carried out in 2003 (all 11-15 year olds) and 2004 (all 16-20 year olds). Reported immunization coverage with a single dose of a rubella-containing vaccine has been more than 95% since 2000. Laboratory-supported surveillance for rubella and CRS was started in 1992. Reported rubella cases fell from 364 (incidence 19/million population) in 1999 to 96 cases (incidence 5/million population) in 2002 and further to 12 cases (incidence 0.6/ million population) in 2014. Laboratory-supported CRS surveillance was started in 1990 and the highest number of CRS cases, 275 (incidence 77/100 000 live births), was diagnosed in 1994. Reported CRS cases fell from 22 cases (incidence 7/100 000 live births) in 2002 to 3 cases (incidence <1/100 000 live births) in 2014. Almost 20 years of routine rubella vaccination has resulted in >96% reduction in reported rubella cases and a corresponding >98% reduction in CRS cases. Despite this great achievement, work remains to eliminate rubella and CRS from Sri Lanka.

Annual risk of tuberculosis infection in Sri Lanka: a low prevalent country with a high BCG vaccination coverage in the South-East Asia Region

INTRODUCTION

Despite its simplicity, efficiency and reliability, Sri Lanka has not used the Annual Risk of Tuberculosis Infection (ARTI) to assess the prevalence and efficiency of tuberculosis (TB) control. Hence, a national tuberculin survey was conducted to estimate the ARTI.

MATERIALS AND METHODS

A school-based, cross-sectional tuberculin survey of 4352 children aged 10 years irrespective of their BCG vaccination or scar status was conducted. The sample was selected from urban, rural and estate strata using two-stage cluster sampling technique. In the first stage, sectors representing three strata were selected and, in the second stage, participants were selected from 120 clusters. Using the mode of the tuberculin reaction sizes (15 mm) and the mirror-image technique, the prevalence and the ARTI were estimated.

RESULTS

The prevalence of TB estimated for urban, rural and estate sectors were 13.9%, 2.2% and 2.3%, respectively. The national estimate of the prevalence of TB was 4.2% (95% CI = 1.7-7.2%). ARTI for the urban, rural and estate sectors were 1.4%, 0.2% and 0.2%, respectively, and the national estimate was 0.4% (95% CI = 0.2-0.7%). The estimated annual burden of newly infected or re-infected TB cases with the potential of developing into the active disease (400/100 000 population) was nearly 10-fold higher than the national new case detection rate (48/100 000 population).

CONCLUSION

The national estimate of ARTI was lower than the estimates for many developing countries. The high-estimated risk for the urban sector reflected the need for intensified, sector-specific focus on TB control activities. This underscores the need to strengthen case detection. Repeat surveys are essential to determine the annual decline rate of infection.

New dengue virus type 1 genotype in Colombo, Sri Lanka

The number of cases and severity of disease associated with dengue infection in Sri Lanka has been increasing since 1989, when the first epidemic of dengue hemorrhagic fever was recorded. We identified a new dengue virus 1 strain circulating in Sri Lanka that coincided with the 2009 dengue epidemic.

Analysis of hospital-based sentinel surveillance data on leptospirosis in Sri Lanka, 2005-2008

In Sri Lanka, leptospirosis is a notifiable disease. In addition to having a routine disease reporting system, Sri Lanka has implemented a hospital-based sentinel surveillance system since 2004. This report discusses the findings of a descriptive analysis of the sentinel surveillance data collected from 2005 to 2008. Of the 4,000 suspected leptospirosis cases, 46.9% and 26.8% were recorded from the Western and Sabaragamuwa provinces, respectively. Most of the individuals were male (83.5%), and approximately 45.6% were aged 30-49 years. Farmers accounted for 16.5%, and laborers for 16.1%; however, the occupation of nearly half (44.8%) of the study population was unknown. More than half (53.9%) of the individuals worked in paddy fields. Almost all had acute fever (98.8%), myalgia (92.9%), and headache (92.7%), but fewer had other related symptoms. Out of the 4,000 individuals, 2,496 (62.4%) underwent a laboratory test; however, the laboratory test results of only 1,445 (57.9%) and the microscopic agglutination results of 41 (2.8%) were available at the sentinel sites. Less than 2% of the reported individuals underwent prophylactic treatment. These findings will help enhance the ongoing efforts for controlling and preventing leptospirosis in Sri Lanka. Sentinel surveillance is a useful tool, but the data quality needs to be improved by supplementing the findings with adequate laboratory diagnosis data.

Leptospirosis outbreak in Sri Lanka in 2008: lessons for assessing the global burden of disease

Global leptospirosis disease burden estimates are hampered by the lack of scientifically sound data from countries with probable high endemicity and limited diagnostic capacities. We describe the seroepidemiologic and clinical characteristics of the leptospirosis outbreak in 2008 in Sri Lanka. Definitive/presumptive case definitions proposed by the World Health Organization Leptospirosis Epidemiology Reference Group were used for case confirmation. Of the 404 possible cases, 155 were confirmed to have leptospirosis. Highest titers of patient seum samples reacted with serovars Pyrogenes (28.7%), Hardjo (18.8%), Javanica (11.5%), and Hebdomadis (11.5%). Sequencing of the 16S ribosomal DNA gene identified six infections: five with Leptospira interrogans and one with L. weilli. In this patient population, acute renal failure was the main complication (14.8%), followed by myocarditis (7.1%) and heart failure (3.9%). The case-fatality rate was 1.3%. This report strengthens the urgent need for increasing laboratory diagnostic capabilities to determine the causes of epidemic and endemic infectious diseases in Sri Lanka, a finding relevant to other tropical regions.

Seroprevalence of rubella antibodies among pregnant females in Sri Lanka

The purpose of this study was to determine the seroprevalence of rubella antibodies among pregnant females in the Kalutara District of Sri Lanka, and to identify factors associated with susceptibility to rubella infection among pregnant females. A cross-sectional clinic-based study was conducted among 620 pregnant women attending antenatal clinics and residing in the district for more than one month. Data on the pregnant females and the socio-economic characteristics of the families were obtained using an interviewer-administered structured questionnaire. Three milliliters of blood was obtained to measure rubella-specific IgG antibody levels by ELISA (enzyme linked immunosorbent assay) tests. Overall, 76% of pregnant females were seropositive for rubella antibodies. Seropositivity in pregnant females increased with age. Susceptibility to rubella was significantly associated with rubella immunization status. Given the high susceptibility rate to rubella infection among pregnant females, it is imperative that any vaccination strategy in the short-term should focus on reducing the number of susceptible women of child-bearing age.

Strategies for immunisation against rubella: evidence from a study in the Kalutara District

OBJECTIVE

To simulate different immunisation programs against rubella and estimate the proportion of the population susceptible to rubella infection of each.

METHODS

The impact of 3 immunisation schedules on the susceptibility of women of childbearing age and the community to rubella infection was simulated using a probabilistic approach. The first schedule involved selective immunisation of 12-year old girls, the second immunisation of all children at 3 years of age for different immunisation coverages, and the third comprised a combination of the first two. The proportion of different segments of the population currently susceptible to rubella was obtained from a field study conducted in the Kalutara District in 1999.

RESULTS

An immunisation program of 12-year old girls will reduce the susceptibility to rubella in 5 years in only the 15 to 19 year age group. In 10 years, the susceptibility in both the 15 to 19 and 20 to 24 year age groups will be reduced. Immunisation only of children at 3 years will take 20 years for a reduction in the susceptibility to rubella infection in the 15 to 19 year and the 20 to 24 year age groups, and the proportion of the population susceptible to rubella can be reduced to less than 10% in 20 years if 90% coverage is attained. If a combination of the two strategies i.e. selective immunisation of girls at 12 years for 10 years and immunisation of all children at 3 years is adopted, the proportion of the community susceptible to rubella will be less than 14% in 10 years.

CONCLUSIONS

The combination of immunising girls at 12 years of age for 10 years and all children at 3 years of age against rubella is recommended for Sri Lanka to reduce the risk of congenital rubella syndrome in the short term and the proportion susceptible to rubella in the community in the long term.