Mapping disease incidence in suburban areas using remotely sensed data.

A method using remotely sensed data was developed to map the incidence of Q fever in the vicinity of Cayenne, French Guiana. A satellite image was processed to map land cover and generate a population density index, which was used to determine areas of high disease incidence during the 1996-2000 period. A comparison with results obtained using population census data showed strong concordance between the two incidence maps. All high-incidence areas identified using population census data were also detected using remotely sensed data. This demonstrates the potential of remote sensing as a new tool for rapid mapping of disease incidence in epidemiologic surveys.

Dengue spatial and temporal patterns, French Guiana, 2001.

To study a 2001 dengue fever outbreak in Iracoubo, French Guiana, we recorded the location of all patients' homes and the date when symptoms were first observed. A geographic information system (GIS) was used to integrate the patient-related information. The Knox test, a classic space-time analysis technique, was used to detect spatiotemporal clustering. Analysis of the relative-risk (RR) variations when space and time distances vary, highlighted the maximum space and time extent of a dengue transmission focus. The results show that heterogeneity in the RR variations in space and time corresponds to known entomologic and epidemiologic factors, such as the mosquito feeding cycle and host-seeking behavior. This finding demonstrates the relevance and potential of the use of GIS and spatial statistics for elaborating a dengue fever surveillance strategy.