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.

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.