Trans-ancestry genome-wide association study identifies 12 genetic loci influencing blood pressure and implicates a role for DNA methylation

We carried out a trans-ancestry genome-wide association and replication study of blood pressure phenotypes among up to 320,251 individuals of East Asian, European and South Asian ancestry. We find genetic variants at 12 new loci to be associated with blood pressure (P = 3.9 × 10(-11) to 5.0 × 10(-21)). The sentinel blood pressure SNPs are enriched for association with DNA methylation at multiple nearby CpG sites, suggesting that, at some of the loci identified, DNA methylation may lie on the regulatory pathway linking sequence variation to blood pressure. The sentinel SNPs at the 12 new loci point to genes involved in vascular smooth muscle (IGFBP3, KCNK3, PDE3A and PRDM6) and renal (ARHGAP24, OSR1, SLC22A7 and TBX2) function. The new and known genetic variants predict increased left ventricular mass, circulating levels of NT-proBNP, and cardiovascular and all-cause mortality (P = 0.04 to 8.6 × 10(-6)). Our results provide new evidence for the role of DNA methylation in blood pressure regulation.

Translational research for Diabetes Self-Management in Sri Lanka: A randomized controlled trial

AIMS

The study tested the hypothesis that a theory driven Diabetes Self-Management (DSM) intervention delivered by trained nurses would result in a clinically significant improvement in glycaemic control.

METHODS

Patients with an HbA1c >7.5% (58mmol/mol) and free of diabetes complications were enrolled into a randomized controlled trial (n=85). Intervention consisted of four sessions and monthly follow up for 6 months. Biochemical tests, and diet and physical activity assessments were done in both groups. Analysis of covariance was used to test the effectiveness of the intervention.

RESULTS

At 6 months, there was a significant difference (P=0.001) in HbA1c between the groups controlling for baseline values and other variables. Based on the primary outcome, 28% in the intervention group achieved the target value of 6.5% HbA1c, compared to 8% in the "usual care" group (P<0.001; η(2)=0.65). The reduction in total energy intake and increase in physical activity was significant in the intervention group between baseline and follow up.

CONCLUSIONS

The DSM intervention has resulted in a clinically significant impact on glycaemia, change in diet and physical activity, and has demonstrated the feasibility of using it within existing care arrangements in a developing country setting.

Evidence-based malaria control in Timor Leste from 2006 to 2012

Background

Malaria has been a major public health problem in the newly established Democratic Republic of Timor Leste with over 200,000 cases being reported in 2006 and 2007. The National Malaria Control Programme (NMCP) was established in 2003. The progress made in malaria control in Timor Leste is reported.

Methods

Records maintained at the NMCP, the district health services, the Health Information and Management System, the National Laboratory on malaria diagnosis and entomological data of the NMCP were reviewed.

Results

There has been a 97% decrease in the reported malaria incidence from 2006 (223,002 cases) to 2012 (6,202 cases). 185,106 clinical cases reported in 2006 decreased to 2,016 in 2012 with introduction and expansion of malaria microscopy services and introduction of monovalent RDTs in 2008 and bivalent RDTs in 2010 in all parts of the country. The National Treatment Guidelines using ACT as the first-line treatment for Plasmodium falciparum infections and introduction of monovalent RDTs, led to a 42% and a 33% decrease from 2007 to 2008 in reported clinical and total malaria cases, respectively. LLINs were distributed initially to pregnant females and children under five and later per every two persons living in high-risk areas (based on microstratification at sub-district level). IRS was carried out in three districts in 2010 and extended to six districts in 2012. Anopheles barbirostris and Anopheles subpictus have been incriminated as malaria vectors. A National Laboratory, which routinely cross checks blood smears for quality assurance of microscopy was established. Malaria focal points at regional, district and sub district level, entomology surveillance staff, monitoring and evaluation officers, and quality control technicians were appointed to strengthen malaria control activities at all levels in the country.

Conclusion

The 97% decrease in the incidence of malaria in Timor Leste is due to application of evidence-based malaria control methods that included enhancing improved quality surveillance, early diagnosis and prompt treatment of cases with effective anti-malarials, targeted vector control, human resource development and deployment, commitment of staff, GFATM funding and technical assistance from WHO.

Systematic fine-mapping of association with BMI and type 2 diabetes at the FTO locus by integrating results from multiple ethnic groups

BACKGROUND/OBJECTIVE

The 16q12.2 locus in the first intron of FTO has been robustly associated with body mass index (BMI) and type 2 diabetes in genome-wide association studies (GWAS). To improve the resolution of fine-scale mapping at FTO, we performed a systematic approach consisting of two parts.

METHODS

The first part is to partition the associated variants into linkage disequilibrium (LD) clusters, followed by conditional and haplotype analyses. The second part is to filter the list of potential causal variants through trans-ethnic comparison.

RESULTS

We first examined the LD relationship between FTO SNPs showing significant association with type 2 diabetes in Japanese GWAS and between those previously reported in European GWAS. We could partition all the assayed or imputed SNPs showing significant association in the target FTO region into 7 LD clusters. Assaying 9 selected SNPs in 4 Asian-descent populations--Japanese, Vietnamese, Sri Lankan and Chinese (n≤26,109 for BMI association and n≤24,079 for type 2 diabetes association), we identified a responsible haplotype tagged by a cluster of SNPs and successfully narrowed the list of potential causal variants to 25 SNPs, which are the smallest in number among the studies conducted to date for FTO.

CONCLUSIONS

Our data support that the power to resolve the causal variants from those in strong LD increases consistently when three distant populations--Europeans, Asians and Africans--are included in the follow-up study. It has to be noted that this fine-mapping approach has the advantage of applicability to the existing GWAS data set in combination with direct genotyping of selected variants.

Genome-wide trans-ancestry meta-analysis provides insight into the genetic architecture of type 2 diabetes susceptibility

To further understanding of the genetic basis of type 2 diabetes (T2D) susceptibility, we aggregated published meta-analyses of genome-wide association studies (GWAS) including 26,488 cases and 83,964 controls of European, East Asian, South Asian, and Mexican and Mexican American ancestry. We observed significant excess in directional consistency of T2D risk alleles across ancestry groups, even at SNPs demonstrating only weak evidence of association. By following up the strongest signals of association from the trans-ethnic meta-analysis in an additional 21,491 cases and 55,647 controls of European ancestry, we identified seven novel T2D susceptibility loci. Furthermore, we observed considerable improvements in fine-mapping resolution of common variant association signals at several T2D susceptibility loci. These observations highlight the benefits of trans-ethnic GWAS for the discovery and characterisation of complex trait loci, and emphasize an exciting opportunity to extend insight into the genetic architecture and pathogenesis of human diseases across populations of diverse ancestry.

Knowledge and perceptions of filariasis in Colombo, Sri Lanka, among patients with chronic filarial lymphoedema

Knowledge of filariasis and perceptions of the disease were explored among 413 lymphoedema cases attending two filariasis clinics in the Colombo district of Sri Lanka. The information was collected in interviews based on a pre-tested, interviewer-administered questionnaire. Only 15% of the patients had initially attributed their limb swelling to filariasis. Most knew that filariasis resulted from mosquito bites (81.1%) and that the disease is transmissible (59.8%) and preventable (74.3%). The majority did not know, or were uncertain, whether filariasis causes swelling of the breasts in females (68.5%), scrotal swelling (60.7%) or dry cough/breathlessness (62.7%). Most (60%) of the interviewees wrongly believed that chronic filarial lymphoedema could be cured, primarily by long-term treatment with diethylcarbamazine. Knowledge of filariasis was significantly associated with level of education (P<0.05). Curiously, compared with the male interviewees, the females interviewed were much less likely to say that filariasis was the cause of their initial swelling (P<0.001). Those who had suffered with the disease for more than 1 year were not significantly more knowledgeable about the disease than the interviewees who had developed symptomatic filariasis more recently. Knowledge about the symptoms of filariasis was generally poor in the study population. In order to dispel several common myths about the disease, health-education programmes, that are targeted both at the community in general and at primary-care providers, are clearly needed.

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.

The burden of diabetes mellitus and impaired fasting glucose in an urban population of Sri Lanka

AIMS

To describe the burden of diabetes mellitus and impaired fasting glucose in middle-aged residents (35-64 years) in an urban area of Sri Lanka.

METHODS

A cross-sectional survey was conducted in the Ragama Medical Officer of Health area, from which 2986 participants (1349 men and 1637 women) were randomly selected from the electoral registry between January and December 2007. The participants underwent a physical examination and had their height, weight, waist and hip circumferences and blood pressure measured by trained personnel. Fasting blood samples were taken for measurement of glucose, HbA(1c) and lipids. The prevalence of diabetes (fasting plasma glucose > 7 mmol/l) and impaired fasting glycaemia (fasting plasma glucose 5.6-6.9 mmol/l) and major predictors of diabetes in Sri Lanka were estimated from the population-based data.

RESULTS

Age-adjusted prevalence of diabetes mellitus in this urban population was 20.3% in men and 19.8% in women. Through the present screening, 263 patients with diabetes and 1262 with impaired fasting glucose levels were identified. The prevalence of newly detected diabetes was 35.7% of all patients with diabetes. Among patients with diabetes, only 23.8% were optimally controlled. In the regression models, high BMI, high waist circumference, high blood pressure and hypercholesterolaemia increased the fasting plasma glucose concentration, independent of age, sex and a family history of diabetes.

CONCLUSIONS

Our data demonstrate the heavy burden of diabetes in this urban population. Short- and long-term control strategies are required, not only for optimal therapy among those affected, but also for nationwide primary prevention of diabetes.

Capacity building in environmental and occupational health in Sri Lanka

BACKGROUND

Although environmental and occupational health (EOH) research and services in Sri Lanka have a long history, policies related to EOH are outdated.

METHODS

We review the International Training and Research in Environmental and Occupational Health (ITREOH) program in Sri Lanka that commenced in 2006 as a collaboration between the University of Alabama at Birmingham and the Faculty of Medicine of the University of Kelaniya, Sri Lanka.

RESULTS

The program has trained over 20 scientists in conducting EOH research. New pioneering research in EOH was initiated. The program was instrumental in furthering the training and research in EOH by initiating a MPH degree program, the first in the country.

CONCLUSIONS

The program has established North-South, South-South and in-country collaborations between institutions and scientists, increasing the visibility of EOH in the future.

Biomass fuel use for cooking in Sri Lanka: analysis of data from national demographic health surveys

BACKGROUND

Biomass cooking fuel is the main source of indoor air pollution in the majority of households in the developing world. Sri Lanka is an island of about 20 million population with urban, rural, and estate population of 14.6%, 80.0%, and 5.4%, respectively. This study describes biomass fuel use for cooking in Sri Lanka.

METHODS

We analyzed data from two national Demographic Health Surveys (2000 and 2007) to identify the use and determinants of cooking fuels in Sri Lankan households. The results are based on a sample of 8,169 households in 2000 and 19,862 households in 2007.

RESULTS

Wood was the principal cooking fuel used in 78.3% and 78.5% of households in 2000 and 2007, respectively. In 2007, 96.3% of estate sector households used firewood as compared to 84.2% in the rural and 34.6% in the urban sectors. Similar trends were noted in 2000 as well.

CONCLUSIONS

The shift from firewood to cleaner fuels in Sri Lanka is negligible from 2000 to 2007. Improving the quality of life of the population does not necessarily predict a shift towards the use of cleaner cooking fuels in Sri Lanka.

Musculoskeletal pain in four occupational populations in Sri Lanka

BACKGROUND

Factors influencing work-related musculoskeletal disorders might differ in developing and developed countries.

AIMS

To assess the prevalence and determinants of musculoskeletal pain in four occupational populations in Sri Lanka.

METHODS

As part of the international Cultural and Psychosocial Influences on Disability study, samples of postal workers, sewing machinists, nurses and computer operators were interviewed about pain at each of six anatomical sites in the past month, and about possible physical and psychosocial risk factors. Associations with prevalent pain were assessed by binomial regression.

RESULTS

Analysis was based on 852 participants (86% response rate). Overall, the lower back was the most common site of pain, with 1-month prevalence ranging from 12% in computer operators to 30% in nurses. Postal workers had the highest prevalence of shoulder pain (23%), but pain in the wrist/hand was relatively uncommon in all four occupational groups (prevalence rates ranged from 8% to 9%). Low mood and tendency to somatize were consistently associated with pain at all six sites. After adjustment for psychosocial risk factors, there was a higher rate of low back pain in nurses and postal workers than in computer operators, a higher rate of shoulder pain in postal workers than in the other occupational populations, and a relatively low rate of knee pain in computer operators.

CONCLUSIONS

Rates of regional pain, especially at the wrist/hand, were lower than have been reported in Western countries. As elsewhere, pain was strongly associated with low mood and somatizing tendency. Differences in patterns of pain by occupation may reflect differences in physical activities.

Physical, psychological, and social aspects of quality of life in filarial lymphedema patients in Colombo, Sri Lanka

Quality of life (QOL) was assessed in 141 filarial lymphedema patients and 128 healthy people in the Colombo district, Sri Lanka, by administering modified, translated, and validated (in Sri Lanka) versions of the Short Form 36 health survey questionnaire (SF-36) and the 30-item General Health questionnaire (GHQ-30). The GHQ-30 assesses the current mental health status. The SF-36 measures health on 8 multi-item dimensions covering functional state, well-being, and overall evaluation of health (physical functioning, role limitations resulting from physical health problems, role limitations resulting from emotional problems, energy/fatigue, emotional well-being, social functioning, pain and general health). By SF-36, patients experienced poorer physical functioning, more role limitations resulting from physical health conditions, less emotional well-being, poorer social functioning, and more pain than healthy individuals. By GHQ-30, mental well-being of healthy controls was significantly better than that of patients. The significant difference in the QOL as perceived by filarial lymphedema patients and healthy individuals reiterates the importance of morbidity control in patients affected by this disease.

Genome-wide association study in individuals of South Asian ancestry identifies six new type 2 diabetes susceptibility loci

We carried out a genome-wide association study of type-2 diabetes (T2D) in individuals of South Asian ancestry. Our discovery set included 5,561 individuals with T2D (cases) and 14,458 controls drawn from studies in London, Pakistan and Singapore. We identified 20 independent SNPs associated with T2D at P < 10(-4) for testing in a replication sample of 13,170 cases and 25,398 controls, also all of South Asian ancestry. In the combined analysis, we identified common genetic variants at six loci (GRB14, ST6GAL1, VPS26A, HMG20A, AP3S2 and HNF4A) newly associated with T2D (P = 4.1 × 10(-8) to P = 1.9 × 10(-11)). SNPs at GRB14 were also associated with insulin sensitivity (P = 5.0 × 10(-4)), and SNPs at ST6GAL1 and HNF4A were also associated with pancreatic beta-cell function (P = 0.02 and P = 0.001, respectively). Our findings provide additional insight into mechanisms underlying T2D and show the potential for new discovery from genetic association studies in South Asians, a population with increased susceptibility to T2D.

Air pollution and health in Sri Lanka: a review of epidemiologic studies

BACKGROUND

Air pollution is increasingly documented as a threat to public health in most developing countries. Evaluation of current air quality levels, regulatory standards and scientific literature on outdoor and indoor air pollution, and health effects are important to identify the burden, develop and implement interventions and to fill knowledge gaps in Sri Lanka.

METHODS

PUBMED and Medline databases, local journals and conference proceedings were searched for epidemiologic studies pertaining to air pollution and health effects in Sri Lanka. All the studies pertaining to air pollution and health effects were considered.

RESULTS

Sixteen studies investigated the association between exposure to ambient or indoor air pollution (IAP) and various health outcomes ranging from respiratory symptoms, low birth weight and lung cancers. Of the sixteen, three used a case control design. Half of the studies collected exposure data only through questionnaires. There were positive associations between air pollution and adverse health effects in all studies. Methodological limitations in most of the studies resulted in poor quantification of risk estimates.

CONCLUSION

A limited number of epidemiological studies in Sri Lanka have investigated the health effects of air pollution. Based on findings of studies and reported air quality levels, air pollution may be considered a neglected public health problem in Sri Lanka.

Hospitalisation trends due to selected non-communicable diseases in Sri Lanka, 2005–2010

OBJECTIVES

To project hospitalisation trends due to selected non-communicable diseases (NCD) from 2005 to 2010.

DESIGN

Morbidity data, maintained at the Medical Statistics Unit of the Ministry of Health, from 1981 to 2000, were used to model trends of hospitalisation due to diabetes mellitus, hypertensive disease and ischaemic heart disease. Linear and quadratic trends were used to model morbidity trends.

RESULTS

For all three diseases considered, the increase in the incidence of hospitalisation is exponential. An increase is estimated in the incidence of hospitalisation by 36%, 40% and 29% due to diabetes mellitus, hypertensive disease and ischaemic heart disease, respectively, in 2010 as compared to 2005. The greatest burden and the largest increase in the rate of hospitalisation will be due to hypertensive disease.

CONCLUSIONS

There will be an exponential increase in hospitalisation due to diabetes, hypertension and ischaemic heart disease. The health sector should provide additional resources to meet the demand.

Anti-tuberculosis drug inducd hepatitis – a Sri Lankan experience

OBJECTIVE

To assess the incidence of anti-tuberculosis (TB) drug induced hepatitis (AIH) in Sri Lankan patients, determine risk factors of AIH, and to address management options in AIH.

DESIGN

A prospective study.

SETTING

Chest Hospital, Welisara, Sri Lanka, from April 2001 to April 2002.

PATIENTS

Seven hundred and eighty three patients with a confirmed diagnosis of TB and resident in the Colombo and Gampaha districts who presented to Chest Hospital, Welisara, Sri Lanka.

METHODS

WHO recommended treatment was commenced in all cases. AIH was diagnosed when patients complained of decreased appetite with nausea or vomiting and elevated serum bilirubin (SB; >1.1 mg/dL) or elevated serum alanine transferase (ALT; > 3 times upper limit of normal).

RESULTS

Of 783 enrolled patients, 74 (9.5%) developed AIH, the majority (58%) developing AIH within the first 2 weeks of the intensive phase of treatment. AIH was more common among patients over 60 years (p = 0.018), who developed pulmonary TB (p = 0.028), and in patients weighing 33-55 kg (p = 0.004). Age, weight and rifampicin overdosage were significant predictors of AIH. Of the 74 AIH patients, standard treatment was restarted in 60, treatment modified in six, two defaulted and six died.

CONCLUSIONS

The incidence of AIH in Sri Lanka is 9.5% in treated patients. AIH was associated with age, low body weight and rifampicin overdosage.

Costs and effectiveness of application of Poecilia reticulata (guppy) and temephos in anopheline mosquito control in river basins below the major dams of Sri Lanka

In this study we examined the costs and effectiveness of using larvivorous fish, Poecilia reticulata, and a chemical larvicide, temephos, in anopheline mosquito control in the riverbeds below the major dams in Sri Lanka. Five riverbeds below the dams, namely Laxapana, Kotmale 1, Kotmale 2, Nilambe, Rantembe and Victoria, were selected. Riverbed pools in Laxapana and Kotmale 1 were treated with P. reticulata; Rantembe and Victoria were treated with temephos; and Kotmale 2 and Nilambe were kept as controls. In each area, the anopheline larval density, before and after application of fish/temephos, was estimated. The cost of application of fish/temephos was estimated by activities involved for each treatment. After intervention, there was a significant reduction in anopheline larval density in the fish-treated areas compared with the temephos-treated and control areas. Application of P. reticulata was 2.67 times less costly than that of temephos. The cost of fish application can be further reduced if the community is involved in the application.

Efficacy of a limb-care regime in preventing acute adenolymphangitis in patients with lymphoedema caused by bancroftian filariasis, in Colombo, Sri Lanka

The efficacy of a programme of community home-based care (CHBC) for lymphoedematous limbs was evaluated among 163 lymphoedema patients attending two filariasis clinics in Colombo. Each patient was interviewed and examined and his or her lymphoedema was graded during a baseline assessment, before the CHBC programme, and again, during a post-intervention assessment, after the patient had been in the programme for 1 year. The number of patients having entry lesions was 24% lower at the post-intervention assessment than at the baseline (P<0.001), with a reduction in the frequency of each type of entry lesion investigated. In the year the patients were in the CHBC programme, 30% fewer of them experienced at least one attack of adenolymphangitis (ADL; P<0.001), the mean number of ADL attacks/patient was lower (P<0.001), and the mean duration of each ADL attack suffered was slightly shorter (5.70 v. 5.84 days; P>0.05) than in the year before the baseline assessment. The reduction in the incidence of ADL attacks was greatest in the patients with the higher grades of lymphoedema. Approximately 66% of the patients perceived an improvement in their swollen limb post-intervention. Eleven patients had grade-II lymphoedema at baseline but only grade-I lymphoedema after being on the CHBC programme for a year (P=0.012). The programme appeared to increase the frequencies with which patients followed each of the limb-care measures considered and most of the measures for the home management of ADL attacks that were investigated. It is recommended that the CHBC programme be implemented as a national programme in Sri Lanka.

An indigenous case of Plasmodium ovale infection in Sri Lanka

Plasmodium ovale, which is generally prevalent only in the African region, has been emerging in the Asian and southeast Asian regions. It has not been reported in Sri Lanka. We report, to our knowledge, an indigenous case of P. ovale infection in Sri Lanka. This patient, who was diagnosed by a polymerase chain reaction, had no history of travel overseas or receipt of a transfusion of blood or any blood products, which makes this a likely case of indigenous transmission. This incidental finding of a P. ovale infection has implications for malaria control in the country and highlights the need to rigorously monitor malaria incidence, as well as prevalent Plasmodium species, with newer and more reliable diagnostics.

Physical disability and psychosocial impact due to chronic filarial lymphoedema in Sri Lanka

Background

Information on the physical and psychosocial disability of lymphatic filariasis in Sri Lanka is scarce. Therefore this study was carried out to describe the physical disability and psychosocial impact associated with chronic lymphoedema in patients attending filariasis clinics in the Colombo district, Sri Lanka.

Methods

Four hundred and thirteen patients with lymphoedema of limbs attending filariasis clinics in Werahera and Dehiwala in the Colombo district were enrolled in the study after obtaining informed written consent. Data were collected using a pre-tested, interviewer-administered questionnaire and analyzed using SPSS.

Results

Majority (95%) of patients had lower limbs affected and there was a significant association with difficulty in walking (p = 0.023). The swollen limb affected the work of 87 (52 %) of employed patients and 26 persons reported loss of job. Approximately 25 % and 6 % reported having problems interacting with the community and family, respectively and 8.7 % felt that they were rejected by society. The swollen limb was perceived as a major problem by 36.8 % of patients. Of the married persons, 5.7 % and 6.2 % reported sexual and marital problems respectively, due to their swollen limb/s. Of those who had marital problems, 77.3% reported sexual problems as well (p < 0.001).

Conclusion

Lymphoedema significantly affects physical, psychological and social functioning in affected individuals. Morbidity control, in addition to control of physical disability, should target the psychosocial consequences.

Evaluation of the effectiveness of the national vitamin A supplementation programme among school children in Sri Lanka

The Ministry of Health in Sri Lanka commenced a vitamin A supplementation programme of school children with a megadose of 105 micromol (100,000 IU) vitamin A in school years 1, 4 and 7 (approximately 5-, 9- and 12-year-olds, respectively) in 2001. We evaluated the vitamin A supplementation programme of school children in a rural area of Sri Lanka. A cross-sectional study was conducted among children supplemented with an oral megadose of vitamin A (105 micromol; n 452) and children not supplemented (controls; n 294) in Grades 1-5. Children were clinically examined and a sample of blood was taken for serum vitamin A concentration estimation by HPLC. Socio-demographic information was obtained from children or mothers. Supplemented children had a higher proportion of males and stunted children, were younger and lived under poorer conditions as compared to controls. There was no difference in the prevalences of eye signs and symptoms of vitamin A deficiency in the two groups. Supplemented children had higher serum vitamin A concentrations than controls (1.4 (SD 0.49) micromol/l v. 1.2 (SD 0.52) micromol/l). The serum vitamin A concentrations were 1.6 (SD 0.45), 1.4 (SD 0.50), 1.3 (SD 0.44) and 1.1 (SD 0.43) micromol/l in children supplemented within 1, 1-6, 7-12 and 13-18 months of supplementation, respectively. Vitamin A concentrations were significantly greater than controls if supplementation was carried out within 6 months after adjustment. The oral megadose of 105 micromol vitamin A maintained serum vitamin A concentrations for 6 months in school children.

Toxicity due to organophosphorus compounds: what about chronic exposure?

The inappropriate use of toxic chemicals is common in developing countries, where it leads to excessive exposure and high risks of unintentional poisoning. The risks are particularly high with the pesticides used in agriculture, where poor rural populations live and work in close proximity to these compounds, which are often stored in and around the home. It is estimated that 99% of all deaths from pesticide poisoning occur in developing countries. Whilst the acute toxicity of pesticides has been well documented, there is still relatively little known of the effects on health of chronic pesticide exposure. Organophosphate insecticides have been extensively used in agriculture in developing countries, with little protection for the communities and individuals thus exposed. Given the indisputable chronic exposure of vulnerable groups to organophosphate compounds, including pregnant women, the fetus and young children, the potential for widespread adverse effects is considerable. Thus, whilst there is some evidence that chronic exposure may have adverse effects on health, there is an urgent need for high-quality observational and interventional studies of both occupational and environmental exposure to these compounds.