Chronic Arsenic Exposure and Risk of Post Kala-azar Dermal Leishmaniasis Development in India: A Retrospective Cohort Study.

BACKGROUND:Visceral leishmaniasis (VL), with the squeal of Post-kala-azar dermal leishmaniasis (PKDL), is a global threat for health. Studies have shown sodium stibogluconate (SSG) resistance in VL patients with chronic arsenic exposure. Here, we assessed the association between arsenic exposure and risk of developing PKDL in treated VL patients. METHODS:In this retrospective study, PKDL patients (n = 139), earlier treated with SSG or any other drug during VL, were selected from the study cohort. Trained physicians, unaware of arsenic exposure, interviewed them and collected relevant data in a questionnaire format. All probable water sources were identified around the patient's house and water was collected for evaluation of arsenic concentration. A GIS-based village-level digital database of PKDL cases and arsenic concentration in groundwater was developed and individual point location of PKDL cases were overlaid on an integrated GIS map. We used multivariate logistic regression analysis to assess odds ratios (ORs) for association between arsenic exposure and PKDL development. RESULTS:Out of the 429 water samples tested, 403 had arsenic content of over 10 μg/L, with highest level of 432 μg/L among the seven study villages. Multivariate adjusted ORs for risk of PKDL development in comparison of arsenic concentrations of 10.1-200 μg/L and 200.1-432.0 μg/L were 1.85 (1.13-3.03) and 2.31 (1.39-3.8) respectively. Interestingly, similar results were found for daily dose of arsenic and total arsenic concentration in urine sample of the individual. The multivariate-adjusted OR for comparison of high baseline arsenic exposure to low baseline arsenic exposure of the individuals in the study cohort was 1.66 (95% CI 1.02-2.7; p = 0.04). CONCLUSION:Our findings indicate the need to consider environmental factors, like long time arsenic exposure, as an additional influence on treated VL patients towards risk of PKDL development in Bihar

Snowball Vs. House-to-House Technique for Measuring Annual Incidence of Kala-azar in the Higher Endemic Blocks of Bihar, India: A Comparison.

Visceral Leishmaniasis, commonly known as kala-azar, is widely prevalent in Bihar. The National Kala-azar Control Program has applied house-to-house survey approach several times for estimating Kala-azar incidence in the past. However, this approach includes huge logistics and operational cost, as occurrence of kala-azar is clustered in nature. The present study aims to compare efficiency, cost and feasibility of snowball sampling approach to house-to-house survey approach in capturing kala-azar cases in two endemic districts of Bihar, India.A community based cross-sectional study was conducted in two highly endemic Primary Health Centre (PHC) areas, each from two endemic districts of Bihar, India. Snowball technique (used to locate potential subjects with help of key informants where subjects are hard to locate) and house-to-house survey technique were applied to detect all the new cases of Kala-azar during a defined reference period of one year i.e. June, 2010 to May, 2011. The study covered a total of 105,035 households with 537,153 populations. Out of total 561 cases and 17 deaths probably due to kala-azar, identified by the study, snowball sampling approach captured only 221 cases and 13 deaths, whereas 489 cases and 17 deaths were detected by house-to-house survey approach. Higher value of McNemar's χ² statistics (64; p1) indicates that most of the kala-azar cases missed by snowball sampling were captured by house-to-house approach with 13% of omission.Snowball sampling was not found sensitive enough as it captured only about 50% of VL cases. However, it captured about 77% of the deaths probably due to kala-azar and was found more cost-effective than house-to-house approach. Standardization of snowball approach with improved procedure, training and logistics may enhance the sensitivity of snowball sampling and its application in national Kala-azar elimination programme as cost-effective approach for estimation of kala-azar burden

Distribution of PKDL cases in respect to variable arsenic concentrations in the study cohort.

<p>Distribution of PKDL cases in respect to variable arsenic concentrations in the study cohort.</p

Distribution of arsenic contamination in groundwater and PKDL cases in the study cohort.

<p>A: Map of Raghopur block showing spatial distribution of inhabitants, B. Distribution of arsenic in groundwater in seven villages of the study cohort, C. Overlap of location of PKDL cases with distribution of arsenic in groundwater in seven villages of the study cohort.</p

Selected confounders in the cohort.

<p>Selected confounders in the cohort.</p

Village-wise PKDL case distribution.

<p>Village-wise PKDL case distribution in the study cohort of Raghopur block, Vaishali district, Bihar, India.</p

Odds ratios (ORs) for risk of PKDL development in the study participants in association to arsenic exposure.

<p>Odds ratios (ORs) for risk of PKDL development in the study participants in association to arsenic exposure.</p

Map of the study cohort.

<p>A. Map of Bihar state, India with the boxed study cohort. B. Detailed map of Raghopur block showing the study cohort with seven villages of interest; details of water bodies, land and inhabitant distribution.</p

Comparative status for history of VL episode of the PKDL cases in the study cohort.

<p>Comparative status for history of VL episode of the PKDL cases in the study cohort.</p