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Investigation of a Dengue Fever Outbreak Among Workers in a Construction Mega-project in Jeddah, November 2019.


Dengue Fever (DF) is a mosquito-borne viral infection. In areas known endemic of DF, such as Jeddah city, construction sites provide favorable environments for mosquitoes breeding due to lower hygiene, poorer sanitation, and insufficient cleaning and vector control; and hence the potential for outbreaks. Objectives: We aimed to investigate a cluster of DF cases that occurred among workers of a large-scale construction site in Southern Jeddah during September - November 2019, as well as to identify the factors associated with contracting DF in the project site so that similar outbreaks could be prevented in the future.


We conducted a field investigation between 17 and 21 November 2019. Identified 53 cases through active cases finding in the construction site using probable & confirmed case definitions of DF in the construction site. A case-control study was performed; Therefore, the projects were shut down for three days.


All cases included in this study were individuals living in Makkah & Jeddah. The mean age was 34.5 years (SD ± 9.8) and all were male workers in the project. The predominant symptoms were fever (41.5 %), headache (34 %), skin rash (33.5 %) and muscles & joints pain (15 %). Factors significantly associated with contracting DF included previous history of DF (OR: 1.97, p < 0.0001) and exposure to mosquito bites (OR: 1.95, p < 0.0001). Protection against mosquito bite was significantly protective (OR: 0.51, p value <0.0001). In environmental investigation, the construction project was affected by a pile-up of waste, formation of pools of stagnant water and proliferation of heavy A. aegypti mosquitoes in adult, pupal and larval forms.


This outbreak happened due to increase of stagnant waters in unattended containers, as these could not be checked regularly to remove stagnant water. This may have led to an increase in habitation and potential breeding sites for mosquitoes.