Spatial analysis of tuberculosis in Douala, Cameroon: clustering and links with socio-economic status

SETTING: Douala, the economic capital of Cameroon, with a network of 20 diagnostic and treatment centres for tuberculosis (TB).OBJECTIVE: To describe the spatial distribution of smear-positive pulmonary tuberculosis (PTB) cases in Douala, Cameroon, and to evaluate links between PTB incidence and patients' socio-economic status (SES).DESIGN: Between May 2011 and April 2012, demographic clinical characteristics and global positioning system coordinates for the residence of each consenting PTB case were collected. Spatial scan statistic was used to identify spatial clusters of tuberculosis. SES data were collected by interview during home visits. PTB patients' SES data were compared with those available for the whole urban population from a recent demographic and health survey. The correlation between PTB incidence and the mean SES of the PTB patients was examined by health area (HA).RESULTS: In total, 2132 (84%) diagnosed PTB cases were identified and interviewed. Three statistically significant spatial clusters were identified. High PTB incidence was predominantly found in HAs characterised by low SES.CONCLUSION: There is evidence of clustering of PTB cases in Douala. Clusters are mainly found in neighbourhoods of low SES. Systematic use of cluster detection techniques for regular TB surveillance in Cameroon might aid in the effective deployment of National TB Programme resources.