Dengue remains a major health problem in Jeddah, Saudi Arabia. An active surveillance system was initiated on daily basis to detect any new case, and during the period from 2006 to 2008, 2,357 cases were reported. The main aim of this study was to analyze these data for detection of space time clustering and thus identifying risk areas and risk periods where control should be targeted.
Methodology
A cross sectional descriptive study conducted in Jeddah that included all confirmed dengue cases by either PCR and/or IgM antibodies and who were residents of Jeddah and had a defined addresses through the surveillance system in the primary health care preventive department during the period from 2006-2008. Cases were first geo-coded at the district level, and then they were analyzed by ArcGIS 9.3 for geographical distribution and by SatScan 8.1 using the space-time permutation model for detection of spatiotemporal clusters of reported cases.
Results
This study showed that dengue infections occurred in a seasonal pattern especially during the first half of the year, affecting mainly males (70.8%) and of 15-44 year age group (67.3%). Fever was the main complaint (51.4%) of cases followed by myalgia (37.3%), retroocular pain (31.4%), headache (29.3%), nausea (25.3%) and backache (22.0%). Skin rash was found in 12.1%. Descriptive spatial analysis showed that the infection has a bipolar pattern, mainly in the south and in the north. Based on the permutation model, space-time permutation scan statistics demonstrated the existence of five spatiotemporal clusters of dengue cases in Jeddah with no variations in risk and clustering by age groups, gender and nationality.
Conclusion
The study has demonstrated that during the period from 2006-2008, dengue was not randomly distributed in Jeddah, and using the existing health data, the spatial scan statistic and GIS can provide public health officials with necessary feedback about the prevalence of statistically significant clusters of dengue.