Dengue and post-infection fatigue: findings from a prospective cohort-the Colombo Dengue Study

BACKGROUND

Previous studies on post-infection fatigue in dengue are few but suggest that up to 25% of dengue patients may suffer from fatigue. This study aimed to evaluate the prevalence and associations of post-infection fatigue in dengue patients compared with non-dengue fever patients.

METHODS

Post-infection fatigue and its demographic and clinical associations were assessed in adult dengue and non-dengue fever patients 2 months after the acute infection in a prospective cohort study in Sri Lanka. Fatigue at 2 months (primary endpoint) was assessed with the fatigue questionnaire as a dichotomous outcome based on a pre-recommended cut-off (score ≥4) and as the total score from the questionnaire (higher score indicates more fatigue).

RESULTS

Of 260 patients, 158 had dengue and, of these, 51 (32%) had fatigue at 2 months. Risk was higher in dengue patients (vs non-dengue; relative risk [RR] 4.93 [95% confidence interval {CI} 2.3 to 10.4]) and more so in female dengue patients (vs male dengue patients; RR 2.45 [95% CI 1.24 to 4.86]). Severe dengue patients had a higher mean fatigue score (p=0.024).

CONCLUSIONS

Post-infection fatigue is an underappreciated burden of this widely prevalent infection. Our findings are useful to triage patients at risk of fatigue for follow-up.

Severe Dengue Epidemic, Sri Lanka, 2017

In 2017, a dengue epidemic of unexpected magnitude occurred in Sri Lanka. A total of 186,101 suspected cases and 440 dengue-related deaths occurred. We conducted a comprehensive analysis of this epidemic by comparing national surveillance data for 2017 with data from the preceding 5 years. In all Sri Lanka districts, dengue incidence in 2017 increased significantly over incidence during the previous 5 years. Older schoolchildren and young adults were more clinically symptomatic than those at extremes of age. Limited virologic surveillance showed the dominant circulating variant was dengue virus type 2 cosmopolitan genotype in the most affected district. One quarter of total annual cases were reported 5 weeks after the southwest monsoon started. Changes in vector abundance were not predictive of the increased incidence. Direct government expenditures on dengue control activities in 2017 were US $12.7 million. The lessons learned from this outbreak are useful for other tropical nations facing increasing dengue incidence.

Success of malaria chemoprophylaxis for outbound civil and military travellers in prevention of reintroduction of malaria in Sri Lanka

BACKGROUND

Sri Lanka was certified as malaria-free in September 2016. However, the continuous presence of the malaria vector poses serious risks of reintroduction of the disease. Chemoprophylaxis and advice on malaria preventive behaviour for international travellers is a key strategy adopted to reduce the risk of imported malaria.

METHODS

We conducted an efficiency study of malaria chemoprophylaxis for civilian and military travellers who requested travel advice from the Anti Malaria Campaign (AMC) prior to departure. The AMC is the only agency that can issue malaria chemoprophylaxis to travellers and hence this sample is representative of all such individuals seeking travel advice in Sri Lanka.

RESULTS

A total of 544 (400 civilians and 144 military) travellers were interviewed prior to departure and after return. The majority travelled to African destinations (516/544 [94.8%]) and were prescribed mefloquine (517/544 [95%]). Chemoprophylaxis was well tolerated and discontinuation due to adverse events was minimal. Regular chemoprophylaxis was reported by 505 (92.8%) participants while overseas. The protective efficacy of chemoprophylaxis was 100% among those who complied with the full course.

CONCLUSIONS

The compliance with chemoprophylaxis and its protective efficacy were satisfactory in this study. It is an effective tool in preventing imported malaria to post-elimination Sri Lanka.

Clinical evidence for repurposing chloroquine and hydroxychloroquine as antiviral agents: a systematic review

BACKGROUND

Repurposing hydroxychloroquine (HCQ) and chloroquine (CQ) as antiviral agents is a re-emerging topic with the advent of new viral epidemics.

AIMS

To summarize evidence from human clinical studies for using HCQ or CQ as antiviral agents for any viral infection.

SOURCES

PubMed, EMBASE, Scopus, Web of Science for published studies without time or language restrictions; Cochrane Clinical Trial Registry and Chinese Clinical Trials Registry for trials registered after 2015; MedRxiv for preprints within the last 12 months.

CONTENT

Study eligibility criteria were interventional and prospective observational studies (with or without a control group). Participants were adults and children with a confirmed viral infection. Interventions included the use of CQ or HCQ as antiviral agent in one or more groups of the study. Two authors independently screened abstracts, and all authors agreed on eligible studies. A meta-analysis was planned if studies were available which were similar in terms of participants, intervention, comparator and outcomes. Nineteen studies (including two preprints) were eligible (HIV 8, HCV 2, dengue 2, chikungunya 1, COVID-19 6). Nine and ten studies assessed CQ and HCQ respectively. Benefits of either drug for viral load suppression in HIV are inconsistent. CQ is ineffective in curing dengue (high-certainty evidence) and may have little or no benefit in curing chikungunya (low-certainty evidence). The evidence for COVID-19 infection is rapidly evolving but at this stage we are unsure whether either CQ or HCQ has any benefit in clearing viraemia (very-low-certainty evidence).

IMPLICATIONS

Using HCQ or CQ for HIV/HCV infections is now clinically irrelevant as other effective antivirals are available for viral load suppression (HIV) and cure (HCV). There is no benefit of CQ in dengue, and the same conclusion is likely for chikungunya. More evidence is needed to confirm whether either HCQ or CQ is beneficial in COVID-19 infection.

Risk prediction for severe disease and better diagnostic accuracy in early dengue infection; the Colombo dengue study

Background

A major challenge in dengue management in resource limited settings is the confirmation of diagnosis. Clinical features of dengue often overlap with other infections and molecular diagnostic tools are not readily accessible to clinicians at hospitals. In addition, the prediction of plasma leakage in dengue is also difficult. Hematocrit level and ultrasound scans (combined with clinical parameters) are helpful to detect plasma leakage once it has happened, not before.

Methods

Colombo Dengue Study (CDS) is a prospective cohort study of clinically suspected adult dengue patients recruited from the National hospital of Sri Lanka (within the first 3 days of fever) that aimed to a) identify clinical and basic laboratory test parameters to differentiate dengue from non-dengue fever, b) evaluate the comparative efficacy of loop-mediated isothermal amplification (LAMP) for dengue diagnosis (vs. NS1 antigen test and RT-qPCR) and c) identify early associations that are predictive of plasma leakage or severe dengue. The basic laboratory tests considered here included hematological parameters, serum biochemistry and inflammatory markers.

Results

Only 70% of clinically suspected patients were confirmed as having dengue by either the NS1 antigen test or RT-qPCR. On a Bayesian latent class model which assumes no “gold standard”, LAMP performed equally or better than RT-qPCR and NS1 antigen test respectively. When confirmed dengue patients were compared with others, the earlier group had significantly lower lymphocyte counts and higher aspartate aminotransferase levels (AST) within the first 3 days of fever. Confirmed dengue patients with plasma leakage had a lower mean age and a higher median baseline AST level compared to those without plasma leakage (p < 0.05).

Conclusion

Clinical suspicion overestimates the true number of dengue patients. RT-LAMP is a potentially useful low-cost diagnostic tool for dengue diagnosis. Confirmed dengue patients had significantly higher AST levels and lower lymphocyte counts in early disease compared to others. In confirmed dengue patients, younger age and a higher AST level in early infection were associated with subsequent plasma leakage.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-4304-9) contains supplementary material, which is available to authorized users.

Use of Bacillus thuringiensis israelensis in integrated vector control of Aedes sp. in Sri Lanka: a prospective controlled effectiveness study

OBJECTIVES

The annual incidence of dengue has been increasing over the last few years in Sri Lanka with seasonal epidemics. Biological control of the vector has not been part of the integrated vector control implemented by the public health authorities of Sri Lanka so far. This pilot study assessed the effectiveness of using Bacillus thuringiensis israelensis (Bti) spray to control the Aedes mosquito vector population density.

METHODS

Prospective controlled effectiveness study in three administrative divisions of Colombo. Study areas were selected from urban, semiurban and rural administrative divisions within the district, and they were compared with two matching controls from the same division. Test areas received three cycles of Bti spraying 1 month apart. Control areas were not sprayed with Bti. Ovitrap and larval indices were calculated at baseline and 2 weeks after each spray cycle.

RESULTS

There was a significant improvement in the adult vector population (ovitrap index) in the test areas after three spray cycles, but this effect had disappeared after 8 weeks (no residual effect). There was no consistent positive impact on larval indices (premise, container and Breteau indices) after each spray cycle.

CONCLUSION

Bti might have a moderate impact on adult vector populations mediated via transient reductions in larval populations. However, this effect is not sustained probably due to rapid re-infestation. Bti spray, if implemented, can only play a supplementary role to other vector control methods.

Association of HLA class I and II genes with cutaneous leishmaniasis: a case control study from Sri Lanka and a systematic review

Background

The outcome of leishmaniasis is an interplay between Leishamania and the host. Identifying contributory host genetic factors is complicated by the variability in phenotype, ethnicity and parasite species. Leishmaniasis is caused exclusively by L. donovani in Sri Lanka with localized cutaneous leishmaniasis (LCL) being the predominant form. We report here an association study of human leucocyte antigen (HLA) class I and II genes with LCL in Sri Lanka, the first on HLA associations in cutaneous leishmaniasis in a South Asian population.

Methods

An existing DNA repository of 200 each of patients and controls was typed for HLA-DQ by PCR-SSP. Next generation sequencing-based typing for HLA-A, HLA-B and HLA-DRB1 alleles was done in a subset of 280 samples. Association tests were performed on 28,489 genotyped and imputed SNPs spanning a region of 1.4 Mb across the HLA genes. To compare our results with similar studies, we carried out a systematic review to document all HLA associations reported to-date for cutaneous and muco-cutaneous leishmaniasis.

Results

DRB1*04 DQB1*02 (P = 0.03; Pc = 0.09), DRB1*07 DQB1*02 (P = 0.03; Pc = 0.09) haplotypes were absent in patients. B*07 (P = 0.007; Pc = 0.13; OR = 0.36; 95 % CI = 0.17–0.77) allele and DRB1*15 DQB1*06 (P = 0.00; Pc < 0.01; OR = 0.3; 95 % CI = 0.2–.0.6) haplotype were over represented in controls and DRB1*15 (P = 0.002; Pc = 0.01) allele was over represented in patients. Two SNPs (rs281864595/rs1050517) in the antigen recognition region of HLA-B, comprised a haplotype more frequent in controls (P = 0.04). The alleles identified by the systematic review to predispose or to protect from cutaneous/mucocutaneous leishmaniasis remained highly heterogeneous in different populations studied.

Conclusions

Our preliminary findings suggest a role for some class I and class II HLA genes in determining predisposition to LCL in this population which should be corroborated with further studies. The systematic review reiterates this need, as the purported susceptibility or protection gained by certain HLA alleles or haplotypes has rarely been independently verified.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1626-8) contains supplementary material, which is available to authorized users.

Effects of modifying the World Health Organization standard operating procedures for malaria microscopy to improve surveillance in resource poor settings

BACKGROUND

Individuals with fever are screened for malaria in specially-established malaria diagnostic laboratories set up in rural hospitals in the Northern and Eastern Provinces of Sri Lanka. Large numbers of blood smears negative for malaria parasites are being screened daily. Good quality smears are essential to maintain a high diagnostic competency among the technical staff. The modifications made to the World Health Organization (WHO) standard operating procedures to improve the quality of smears have been studied.

METHODS

A blinded, controlled, interventional study was conducted in 22 intervention and 21 control malaria diagnostic laboratories. Changes were made to the WHO standard operating procedure protocols to prepare, stain and examine blood smears for malaria parasite detection which were implemented in intervention laboratories. These included wipe-cleaning slides, preparing both thick and thin smears on the same slide, reversing the order of collecting blood for thick and thin smears, dry fixing thick smear for 20-25 minutes under table lamp, polishing the edge of spreader slide with sand paper and fixing the thin smear with methanol if not stained within four hours. Parameters with respect to quality of the smear as per WHO criteria were studied using randomly selected slides, and time taken for the report to be issued was recorded in both groups before and after the intervention.

RESULTS

There were no significant differences observed in the parameters studied at baseline between the two groups or pre and post intervention in the control group. In the intervention group streak formation in thin smears was reduced from 29.4% to 5.0%. The average fixing time of thick smears was reduced from 2.4 hours to 20 minutes. Inappropriate thickness of thick smears reduced from 18.3% to 1.5%. Overall quality of thick smears and thin smears increased from 76.1% to 98.0% and 81.7% to 87.0%, respectively. The quality of slides bearing both thick and thin smears increased from 60.0% to 87.0%.

CONCLUSIONS

New protocols with amendments to the WHO standard technical procedures ensure that good quality blood smears are prepared rapidly to diagnose malaria and the time required to issue the reports was reduced.

Diagnosis and treatment of malaria by health care providers: findings from a post conflict district in Sri Lanka

This study determines whether 72 health care providers in a previously conflict-affected district in Sri Lanka adhere to the recommendations of the Anti Malaria Campaign with regard to diagnosis, prescribing antimalarials and reporting of a positive case. All patients suspected of clinically having malaria are being referred for laboratory confirmation, indicating that presumptive treatment is not practiced. The knowledge amongst health care providers regarding accurate management and reporting of a malaria positive case needs to be improved.

Imported malaria: a possible threat to the elimination of malaria from Sri Lanka?

OBJECTIVE

To discuss epidemiological aspects of imported malaria and the potential impact of imported malaria cases reported in Sri Lanka 2008-2011 in terms of a possible resurgence of the disease.

METHODS

The national malaria database was used to assess details regarding country where the infection was possibly acquired, species of Plasmodium, number of days lapsed between disembarkation in Sri Lanka and diagnosis, compliance with national treatment guidelines including percentage of patients followed up as per the national guidelines.

RESULTS

After the strengthening of malaria surveillance, during the 4-year period, 152 imported malaria cases were recorded: an increase of 176% in the number of cases. Most of the imported malaria infections were acquired by Sri Lankan Nationals mainly from South Asia, especially India. Plasmodium vivax accounted for 64% of the infections. Approximately 50% of the cases were diagnosed in the Western Province. The average period from disembarkation in Sri Lanka to malaria diagnosis was 3.6 days. Patients were managed and treated according to the national guidelines. 82% of the patients were followed up for 28 days to ensure parasite clearance.

CONCLUSIONS

There is a possible increasing risk of re-introduction of malaria to the country from imported cases. Enhanced surveillance activities and the increase in international travel have contributed to an increase in recorded case numbers. There is a need to further strengthen surveillance, especially for monitoring and timely addressing of imported malaria, if the country is to prevent the re-establishment of transmission within. The importance of having an efficient response mechanism to deal with imported malaria is also highlighted.

Genetic polymorphisms associated with anti-malarial antibody levels in a low and unstable malaria transmission area in southern Sri Lanka

Background

The incidence of malaria in Sri Lanka has significantly declined in recent years. Similar trends were seen in Kataragama, a known malaria endemic location within the southern province of the country, over the past five years. This is a descriptive study of anti-malarial antibody levels and selected host genetic mutations in residents of Kataragama, under low malaria transmission conditions.

Methods

Sera were collected from 1,011 individuals residing in Kataragama and anti-malarial antibodies and total IgE levels were measured by a standardized ELISA technique. Host DNA was extracted and used for genotyping of selected SNPs in known genes associated with malaria. The antibody levels were analysed in relation to the past history of malaria (during past 10 years), age, sex, the location of residence within Kataragama and selected host genetic markers.

Results

A significant increase in antibodies against Plasmodium falciparum antigens AMA1, MSP2, NANP and Plasmodium vivax antigen MSP1 in individuals with past history of malaria were observed when compared to those who did not. A marked increase of anti-MSP1(Pf) and anti-AMA1(Pv) was also evident in individuals between 45–59 years (when compared to other age groups). Allele frequencies for two SNPs in genes that code for IL-13 and TRIM-5 were found to be significantly different between those who have experienced one or more malaria attacks within past 10 years and those who did not. When antibody levels were classified into a low-high binary trait, significant associations were found with four SNPs for anti-AMA1(Pf); two SNPs for anti-MSP1(Pf); eight SNPs for anti-NANP(Pf); three SNPs for anti-AMA1(Pv); seven SNPs for anti-MSP1(Pv); and nine SNPs for total IgE. Eleven of these SNPs with significant associations with anti-malarial antibody levels were found to be non–synonymous.

Conclusions

Evidence is suggestive of an age–acquired immunity in this study population in spite of low malaria transmission levels. Several SNPs were in linkage disequilibrium and had a significant association with elevated antibody levels, suggesting that these host genetic mutations might have an individual or collective effect on inducing or/and maintaining high anti–malarial antibody levels.

Improving diagnosis of trichomonas vaginalis infection in resource limited health care settings in sri lanka

OBJECTIVE

This study was designed to compare diagnosis of trichomoniasis by culture, wet smear examination, and Giemsa stain. A modified technique was used to transport and prepare the specimen to ensure parasite viability prior to Giemsa staining.

MATERIALS AND METHODS

A clinic-based prospective study was carried out in association with the National STD/AIDS Control Programme over a period of 18 months. Three swabs were collected from the posterior fornix of 346 newly registered female patients for diagnosis of trichomoniasis. A wet smear was prepared using the first swab. The second swab was placed in 5 mL of 0.9% saline with three drops of 5% glucose at room temperature and centrifuged twice at a low speed prior to preparation of a Giemsa stained smear. The third swab was for culture. The three tests were performed independently. The specificity and sensitivity of the wet smear and Giemsa stain were compared to culture.

RESULTS

With culture, the prevalence of trichomoniasis was 6.9% (95% CI: 4.1-9.3%). The Giemsa-stained smear was found to be highly sensitive (100%, 95% CI: 86.2-100%) and specific (99.69%, 95% CI: 98.26-99.95%) compared to culture. The wet smear was less sensitive (95.83%, 95% CI: 79.76-99.26%) but equally specific (100%, 95% CI: 98.82-100%).

CONCLUSION

In developing countries, facilities for using culture are limited and wet smear examination in the field is also difficult due to the immediate need for laboratory facilities. Our study demonstrated that, in this setting, using a transport medium prior to Giemsa staining is a feasible alternative, with a high-diagnostic yield.

Clinical features and sociodemographic factors affecting Trichomonas vaginalis infection in women attending a central sexually transmitted diseases clinic in Sri Lanka

Introduction:

Trichomoniasis is a relatively neglected area of research in Sri Lanka. Given the number of infections observed, an analysis of sociodemographic characteristics of patients would be valuable in prevention.

Materials and Methods:

Data were collected from 359 newly registered women at a tertiary level sexually transmitted diseases clinic over a period of 18 months. Trichomoniasis was diagnosed by culture of vaginal swabs collected from the posterior fornix.

Results:

The prevalence of trichomoniasis in the sample was 7.2%. Of those who tested positive for trichomoniasis, 76% were in the age group of 21-45 years, 68% were married and living with a spouse and 60% were unemployed. A diagnosis of Trichomoniasis was associated with being married (OR, 1.6; CI, 0.56-4.41), age over 33 years (OR=1.3, CI, 0.55-2.9), being employed (OR, 1.3; CI, 0.56 – 2.94), having an education of less than ten years at school (OR, 3.0; CI 1.28-7.26) and not using condoms during the last sexual act (OR 2.0, CI 0.84-4.86). The risk was less among commercial sex workers (OR, 0.3, CI: 0.14-0.85), those with multiple sexual partners (OR, 0.2; CI; 0.073-0.408) and women reporting extramarital sexual relationships (OR, 0.3; CI, 0.128-0.733).

Conclusions:

Education on safe sex and recognition of symptoms is currently targeted at high risk groups such as commercial sex workers. Extending these programmes to the rest of the community will further reduce the risk of transmission of trichomonas.

Malaria is an important differential diagnosis in visitors returning from Sri Lankan National Safari Parks

Diagnostic confusion may occur between dengue and malaria when febrile patients with thrombocytopenia return from travel to previous malaria endemic areas. Laboratory tests should include blood smear examination for malaria parasites even though current malaria endemicity in Sri Lanka is low.

The 'hidden' burden of malaria: cognitive impairment following infection

BACKGROUND

The burden of post-malaria cognitive impairment is often overlooked. Given the large number of infections occurring worldwide, the magnitude of the problem is likely to be substantial. The objectives of this paper are; (i) to assess the evidence on post malarial cognitive impairment or impact on school education; (ii) to assess the possible positive impact of malaria drug prophylaxis on cognition; and (iii) to suggest recommendations on minimizing the burden of post-malarial cognitive impairment.

METHODS

PUBMED and SCOPUS were searched for all articles with the key word 'Malaria' in the title field and 'cognitive impairment' in any field. Google Scholar was searched for the same keywords anywhere in the article. The search was restricted to articles published in English within the last 15 years (1995-2010). After filtering of abstracts from the initial search, 44 papers had research evidence on this topic.

RESULTS & DISCUSSION

Cognitive abilities and school performance were shown to be impaired in sub-groups of patients (with either cerebral malaria or uncomplicated malaria) when compared with healthy controls. Studies comparing cognitive functions before and after treatment for acute malarial illness continued to show significantly impaired school performance and cognitive abilities even after recovery. Malaria prophylaxis was shown to improve cognitive function and school performance in clinical trials when compared to placebo groups. The implications of these findings are discussed.

Candidate gene study of susceptibility to cutaneous leishmaniasis in Sri Lanka

OBJECTIVES

To investigate the association between selected single nucleotide polymorphisms (SNPs) in TNF, LTA and SLC11A1 genes and risk of endemic cutaneous leishmaniasis (CL) in Sri Lanka through a case-control disease association study.

METHODS

An anonymized DNA resource representative of the Sri Lankan population was genotyped initially to establish baseline parameters. This was followed up by genotyping 200 patients and 200 matched controls. Published or modified PCR/RFLP methods were employed for genotyping.

RESULTS

Comparison of the different ethnic groups showed the distribution of alleles of LTA +252 A>G to differ significantly in Tamils and Moors when compared with Sinhalese. The differences seen at allele level were also reflected in the haplotypes defined by these SNPs at the TNF locus. The case-control analysis did not show an association between the SNPs or the haplotypes investigated and CL. The distribution of these variant alleles in other populations, where they are positively associated with leishmaniasis, differed significantly from the Sri Lankan study cohort.

CONCLUSIONS

The selected polymorphisms do not predispose to CL in the Sri Lankan population. The study of extended haplotypes at these loci using a sufficiently powered sample collection would elaborate the findings of this study. In the face of an evolving disease pattern in the country with other forms of leishmaniasis now being reported, prevalence of polymorphisms predisposing to these forms calls for heightened surveillance and preparedness.

Anthelmintic prescribing patterns of a sample of general practitioners from selected areas in the Colombo district of Sri Lanka

General Practitioners (GPs) provide first contact care of children and pregnant mothers in the community. This study ascertained the prescribing pattern of anthelmintics to children and pregnant women by a sample of GPs from the district of Colombo. Two hundred medical practitioners engaged in full-time General Practice (100 urban and 100 rural), were selected randomly. A pre-tested interviewer-administered questionnaire was used to collect data. A total of 183 GPs aged between 26 and 72 years (median 38) participated with 94 coming from urban areas. Seventy percent of the GPs were male. Almost 13% of GPs from urban areas had a Postgraduate degree in comparison to 4.5% from the rural areas (P < 0.05). Over 50% of GPs had 6-20 years of service and over 30% treated 16-30 patients daily. Seventy-three percent of GPs from rural areas accessed health-related reading material either daily or weekly in contrast to only 40% from urban areas (P < 0.001). All GPs prescribed anthelmintics to children. Pyrantel pamoate was the preferred anthelmintic used for children by both groups. Approximately 55% and 64% of GPs from urban and rural areas, respectively, prescribed anthelmintics during pregnancy. A majority of GPs prescribed drugs after the first trimester. However, 25% from urban areas gave drugs during any trimester (P < 0.001). Regression analysis revealed that GPs with postgraduate qualifications, those having frequent access to health-related material and those seeing more than 30 patients daily, prescribed anthelmintics to pregnant women more often. Although routine de-worming of pregnant women and children should occur through government antenatal and well-baby clinics, and through the schools de-worming programme, it may not happen due to various reasons. Thus, GPs play a vital role in achieving good coverage of anthelmintics among children and pregnant women. Making available clear national guidelines on prescribing anthelmintics in Sri Lanka would improve the prescribing patterns of anthelmintics among GPs.

Epidemiological aspects and risk factors of toxocariasis in a pediatric population in Sri Lanka

This cross-sectional study, carried out over a period of 11 months, investigated the relationship between Toxocara seropositivity, socio-demographic and environmental variables in a pediatric population. Risk factors for Toxocara infection were assessed by direct interview of parent or guardian using a structured pre-tested questionnaire. Eosinophilia and presence of helminth eggs or protozoan cysts in a fecal smear were recorded. Diagnosis of Toxocara seropositivity in children was based on IgG Toxocara Microwell Serum Elisa Kits. The ELISA test was regarded as positive if the optical density was 0.3 units or above. Unadjusted and adjusted odds ratios were calculated to determine risk factors for disease. The proportion of children who were positive for Toxocara antibodies in the study population was 20%. Children being exposed to a puppy of less than 3 months at home, visiting a playground frequently, living in a poorly constructed house and dogs having access to playgrounds were significant risk factors on univariate analysis. Of these four variables, only the first three variables (OR 19, OR 4 and OR 3, respectively) remained significant risk factors on the multivariate model. Presence of eosinophilia in seropositive children was significantly higher than the seronegative group (77% vs 40%; p < 0.001). This study indicates that dogs contribute significantly to children being seropositive for toxocariasis in Sri Lanka. Implementation of public health programs specifically focused on anti-parasitic treatment of dogs is recommended.

Evaluation of a rapid whole blood immunochromatographic assay for the diagnosis of Plasmodium falciparum and Plasmodium vivax malaria

OBJECTIVE

Microscopic examination of blood smears is the 'gold standard' for malaria diagnosis, but is labour intensive and requires skilled operators. Plasmodium vivax malaria accounts for up to 70% of infections in Sri Lanka. The objective of this study was to determine the effectiveness of an immunochromatographic test which can detect both the species of Plasmodium, P. vivax and P. falciparum, present in Sri Lanka.

DESIGN

Prospective study from May 2001 to March 2002.

SETTING AND METHODS

All persons above 5 years of age who presented to the Malaria Research Station, Kataragama or the Anti-malaria Clinic, Kurunegala, with a history of fever were recruited to the study. Thick and thin blood smears were examined for malarial parasites. The rapid diagnostic test (RDT), ICT Malaria P.f/P.v (AMRAD ICT, Australia) was performed simultaneously by an independent investigator. The severity of clinical disease of all patients was evaluated.

RESULTS

The study sample comprised 328 individuals of whom 126 (38%) were infected, 102 with P. vivax (31.1%) and 24 with P. falciparum (7.3%). The RDT was found to be highly sensitive (100%) and specific (100%) for the diagnosis of P. falciparum when compared with field microscopy. The sensitivity for the diagnosis of P. vivax malaria was only 70%. When P. vivax parasitaemia was greater than 5000 parasites/microL the RDT was 96.2% sensitive. A significant association was noted between the band intensity on the dipstick and both peripheral blood parasitaemia (p < 0.001) and clinical severity of disease with P. vivax (p = 0.011).

CONCLUSIONS

The ICT Malaria P.f/P.v test can be used in Sri Lanka in the absence of microscopists.

A cost analysis of the use of the rapid, whole-blood, immunochromatographic P.f/P.v assay for the diagnosis of Plasmodium vivax malaria in a rural area of Sri Lanka

Between May 2001 and March 2002, a prospective study was conducted in a malaria-endemic area of Sri Lanka, to determine the cost implications of using the immunochromatographic P.f/P.v test to detect Plasmodium vivax infection. All consecutive subjects aged >5 years who presented with a history of fever were recruited. Each was checked for P. vivax infection by the standard microscopical examination of bloodsmears and by the immunochromatographic test (ICT). The costs of diagnosis using each method and the sensitivity, specificity and predictive values of the ICT (with bloodsmear examination used as the 'gold standard') were estimated, the costs/case detected being simulated for different slide positivity 'rates' and ICT sensitivities. In the detection of P. vivax, the ICT had a sensitivity of 70% and a specificity of 99%. The costs of the ICT per subject investigated and per case detected were, respectively, approximately 14 and 20 times more than those of bloodsmear examination. The costs of the ICT per case detected would fall as the sensitivity of the test increased. The ICT gave relatively few false-positive results. The current, relatively high cost of the ICT is the most important barrier to its routine operational use in the diagnosis of malaria. The test is already useful, however, in specific situations.

The impact of repeated malaria attacks on the school performance of children

The impact of repeated malarial infections on the school performance of children was investigated in 571 school children 6-14 years of age in a malaria-endemic area in southern Sri Lanka where both Plasmodium falciparum and P. vivax infections are prevalent. Malaria infections confirmed by microscopy were monitored over a six-year period. School performance was assessed by two specially designed, school grade-specific, test papers for Sinhala language and mathematics. The scores for Sinhala language and mathematics for each school term test for the year 1997 were obtained. Malarial infections were a major predictor of children's performance in language and mathematics after controlling for parent's education, monthly family income, and house type. The education of the father predicted language scores but not mathematics scores. A child who experienced more than five attacks of malaria scored approximately 15% less than a child who experienced less than three attacks of malaria. The data suggest that repeated attacks of malaria have an adverse impact on the school performance of children.

Antibodies to hepatitis C virus in patients who have had multiple transfusions in Sri Lanka

OBJECTIVE

To determine the prevalence of antibodies to hepatitis C virus (HCV) in patients who have had multiple transfusions in Sri Lanka.

SETTING

University Medical Unit at the National Hospital, Colombo, the Cancer Institute, Maharagama, and the Lady Ridgeway Children's Hospital, Colombo.

PATIENTS

One to 5 ml of blood for serology was collected from 200 multiply transfused patients (those who have received five or more blood transfusions).

METHOD

The sera were tested for HCV specific antibodies using a third generation anti-HCV enzyme immuno-assay (EIA) kit. All sera giving positive or intermediate EIA results were re-tested by a commercial HCV Western blot confirmatory test.

RESULTS

Of the 200 patients, 10 (5%) were repeatedly positive and confirmed by the Western blot. 33% (7/21) of haemophiliacs and 10% (3/31) of thalassaemics were positive for antibodies to HCV. Antibodies were not detected in other groups of multiply transfused patients (haemolytic disease, aplastic anemias, chronic renal failure, haematological and other malignancies). Of the 200 patients, those who have had more than 80 blood transfusions had a significantly higher prevalence of antibodies to HCV. The frequency of HCV infection was also higher among those who had received factor concentrates.

CONCLUSION

33% of haemophiliacs and 10% of thalassaemics who have received multiple transfusions were infected with HCV. These findings warrant a larger study among blood donors, and justify screening and decontamination of blood and blood products given to haemophiliacs and thalassaemics in Sri Lanka.

Geo-helminth infections in a rural area of Sri Lanka

School children carry the heaviest burden of morbidity due to intestinal helminth infection. The objective of this investigation was to study geo-helminth infections in 349 school children aged 6 to 13 years living in a rural area of Sri Lanka. Stool samples were examined by direct saline smear in an initial survey to determine the prevalence of intestinal parasitic infections and thereafter the children were followed up over a two year period with cross sectional surveys of stool samples being carried out at yearly intervals. Following collection of a stool sample, all the subjects were treated with mebendazole 500 mg as a single dose. Weights and heights were measured using standardized procedures. 2 ml of venous blood were collected from each subject under aseptic conditions to determine hematological indices. The prevalence of geo-helminth infections was low, and the prevalence declined during the two-year period from 5.4% in 1997 to 2.2% in 1998 and 2.0% in 1999 following yearly mass anti-helminth treatment. The incidence density was 0.021 cases per child year. The reduction in the prevalence from the baseline to the second survey is probably due to the reduction of the reservoir of infection among children as a result of mass treatment at baseline. The prevalence of infection during the second and third surveys were almost the same probably due to infections originating from other segments of the untreated population.

The health and nutritional status of school children in two rural communities in Sri Lanka

There is growing evidence of considerable burden of morbidity and mortality due to infectious diseases and undernutrition in school children. This study describes the nutritional status and parasitic infections of school children in two areas of rural Sri Lanka. All children in four primary schools in the Moneragala district of Sri Lanka were included in the study. The height and weight of children were measured and anthropometric indices calculated. Stool and blood samples were examined for evidence of intestinal helminthiasis, malaria and anaemia. A greater proportion of boys than girls were underweight, wasted and stunted. Over 80% of the children were anaemic but did not apparently have iron deficiency anaemia according to their blood picture. The prevalence of parasitic infections such as hookworm and Plasmodium spp that may contribute to anaemia was low.

A histochemical study of adenosine triphosphatase in neuroglia

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