Active surveillance of Hansen's Disease (leprosy): importance for case finding among extra-domiciliary contacts.

Hansen's disease (leprosy) remains an important health problem in Brazil, where 34,894 new cases were diagnosed in 2010, corresponding to 15.3% of the world's new cases detected in that year. The purpose of this study was to use home visits as a tool for surveillance of Hansen's disease in a hyperendemic area in Brazil. A total of 258 residences were visited with 719 individuals examined. Of these, 82 individuals had had a previous history of Hansen's disease, 209 were their household contacts and 428 lived in neighboring residences. Fifteen new Hansen's disease cases were confirmed, yielding a detection rate of 2.0% of people examined. There was no difference in the detection rate between household and neighbor contacts (p = 0.615). The two groups had the same background in relation to education (p = 0.510), household income (p = 0.582), and the number of people living in the residence (p = 0.188). Spatial analysis showed clustering of newly diagnosed cases and association with residential coordinates of previously diagnosed multibacillary cases. Active case finding is an important tool for Hansen's disease control in hyperendemic areas, enabling earlier diagnosis, treatment, decrease in disability from Hansen's disease and potentially less spread of Mycobacterium leprae.

Geographic information systems and applied spatial statistics are efficient tools to study Hansen's disease (leprosy) and to determine areas of greater risk of disease.

Applied Spatial Statistics used in conjunction with geographic information systems (GIS) provide an efficient tool for the surveillance of diseases. Here, using these tools we analyzed the spatial distribution of Hansen's disease in an endemic area in Brazil. A sample of 808 selected from a universe of 1,293 cases was geocoded in Mossoró, Rio Grande do Norte, Brazil. Hansen's disease cases were not distributed randomly within the neighborhoods, with higher detection rates found in more populated districts. Cluster analysis identified two areas of high risk, one with a relative risk of 5.9 (P = 0.001) and the other 6.5 (P = 0.001). A significant relationship between the geographic distribution of disease and the social economic variables indicative of poverty was observed. Our study shows that the combination of GIS and spatial analysis can identify clustering of transmissible disease, such as Hansen's disease, pointing to areas where intervention efforts can be targeted to control disease.

The use of Geographical Information System (GIS) to improve active leprosy case finding campaigns in the municipality of Mossoró, Rio Grande do Norte State, Brazil.

There is a high incidence of leprosy in the municipality of Mossor6, Rio Grande do Norte state, where the detection coefficient has risen from 2.78/10,000 population in 1998 to 5.14 in 2004. While cases have been registered throughout the urban area, the disease is concentrated in select neighbourhoods. This study was undertaken using Geographical Information System (GIS) with the objective of defining low-cost, effective strategies to control leprosy. The land registry map of the city, Ikonos satellite images and the SINAN (National Morbidity Notification Information System) database were used as the cartographical basis for the study. The sample for the leprosy mapping was drawn from the 358 new cases of the disease diagnosed in the municipality between 1998 and 2002. The houses of 281 patients were located (78.5% of the total) and their addresses geo-referenced using a GPS handheld device. Subsequently, geographical analysis was carried out using ArcView 9.0 software showing predominant concentration of cases in the neighbourhoods of Barrocas, Santo Antônio, Bom Jardim and Paredões. This mapping served as the basis for four active case finding campaigns conducted in the most highly concentrated areas between March and September of 2005. Campaigns guided by spatial analysis led to the diagnosis of 104 new cases of the disease (50% of the total number of new cases detected in the municipality in 2005). The use of GIS in leprosy diagnosis has shown to be extremely effective, providing a clear visual understanding of the distribution of the disease in the municipality, which results in targeted interventions and important cost reductions in leprosy control activities.

Distribuição espacial da hanseníase no município de Mossoró/RN, utilizando o Sistema de Informação Geográfica - SIG / Spatial Distribuition of hansen disease in the municipality of Mossoró/RN, using the Geographic Infromation System - (GIS)

FUNDAMENTOS/OBJETIVO: O município de Mossoró, no Estado do Rio Grande do Norte, tem um elevado coeficiente de detecção de hanseníase, que passou de 2,78 em 1998 para 5,08 casos novos por 10.000 habitantes em 2002. O registro de casos vem ocorrendo em toda a zona urbana, porém com maior concentração em alguns bairros. Esse trabalho foi realizado utilizando-se o Sistema de Informações Geográficas (SIG) com o objetivo de determinar a localização espacial da doença, buscando um melhor entendimento da endemia no município. MATERIAL E MÉTODOS/CASUíSTICA: O estudo foi realizado na área urbana de Mossoró e utilizou como bases cartográficas o mapa cadastral da cidade e imagem de satélite Ikonos, além do banco de dados do SINAN (Sistema de Informação de Agravos de Notificação). Foram selecionados 358 casos novos da doença diagnosticados entre 1998 e 2002 para georreferenciamento dos seus endereços usando-se um aparelho GPS (Magellan 320). A análise geográfica foi feita através do ArcView 9.0. RESULTADOS/DISCUSSÃO: Foram localizados os endereços de 281 pacientes (78,5 por cento do total) com grande concentração nos bairros de Barrocas, Santo Antônio, Bom Jardim e Paredões. O mapeamento serviu de base para a realização de campanha para diagnóstico, especialmente direcionada para áreas mais endêmicas, levando ao diagnóstico de 30 casos novos da doença em apenas uma semana (ou 27 por cento de todos os casos novos do município em 2004). CONCLUSÃO: O uso do SIG na hanseníase se mostrou extremamente eficaz, proporcionando o entendimento espacial da distribuição da doença no município e direcionando a execução de ações de controle com importante redução de custos.

BACKGROUND / OBJECTIVES: The Municipality of Mossoró, in Rio Grande do Norte State in Brazil, has a high incidence of Hansen's disease (HD). New case detection rate has increased from 2.78 in 1998 to 5.08 new cases per 10.000 population in 2002. New patients have been registered in all urban zones but there is concentration in some areas. This study used Geographic Information Systems (GIS) to determine the spatial localization of HD cases, trying to get a better understanding of epidemiological aspects at the municipal level. MATERIAL AND METHODS: The study was carried out in the urban area of Mossoró and used as its cartographic base the standard map of the city and images from Ikonos Satellite, and SINAN Database (Sistema de Informação de Agravos de Notificação). The addresses of 358 new cases diagnosed from 1998 to 2002 were selected to be geo-referenced using a GPS hand held device (Magellan 320). Geographic analysis was done using ArcView 9.0. RESULTS: 281 addresses (78.5 percent of the total) were localized showing high concentration of cases in Barrocas, Santo Antônio, Bom Jardim e Paredões neighborhoods. The maps were used to choose an endemic area where a case detection campaign was carried out and had the positive outcome of 30 new cases of HD detected in only one week (equivalent of 27 percent of all new cases detected in 2004). CONCLUSION: The use of GIS in HD proved to be extremely efficient, revealing the spatial pattern of case distribution and guiding the execution of activities with important cost reduction.