Since 1994, dengue fever (DF) transmission rates have increased significantly in Saudi Arabia (KSA). Climatic, geographic, and demographic conditions make KSA especially suitable for DF’s spread. Still, there are insufficient strategies for controlling the Aedes species that transmit DF virus (DENV). To develop effective management strategies, it is necessary to identify Aedes species and the ecological habitat of larvae in Makkah Al-Mokarramah, KSA. We conducted a longitudinal survey of Aedes mosquitoes in 14 localities from January 2015 to December 2015. World Health Organization (WHO) inspection kits for larvae were used to detect and sample larvae, along with pictorial keys. A total of 42,981 potential Aedes larval breeding sites were surveyed. A total of 5403 (12.6%) sites had at least one water source positive for Aedes aegypti (Linnaeus) mosquitoes. Among the total of 15,133 water sources surveyed within the sampled sites, 1815 (12.0%) were positive for Aedes aegypti. Aedes aegypti was the only Aedes species identified in the course of the survey. The presence of such a large immature population may indicate an imminent outbreak of DF in the near future unless proper implementation of control and elimination of Aedes aegypti are undertaken. Additionally, the adaptation of Aedes aegypti to the arid climate of Makkah needs further investigation.

Dengue fever (DF) is endemic to Makkah and Jeddah, the Kingdom of Saudi Arabia (KSA). However, until recently, the circulation of dengue virus (DENV) in Aedes mosquitoes in these areas was unknown. Serological surveillance of DENV in Ae aegypti is a powerful tool for early detection of dengue outbreaks and essential for developing effective control strategies. Therefore, this research aimed to examine a sample of adult Ae aegypti mosquitoes from Makkah, KSA, to detect DENV. In total, 1295 Ae aegypti mosquitoes were collected from the field from target areas of Makkah with a high incidence and prevalence of DF. The samples were divided into 259 coded pools (five mosquitoes in each) and preserved in 1.5 mL plastic tubes. The tubes were labeled, capped, and stored at−86°C until use. RT-PCR was used to detect DENV in the samples. All positive pools were confirmed by RT-PCR. The RT-PCR products were analyzed by gel electrophoresis (1.5% agarose in Tris-acetate EDTA buffer), stained with ethidium bromide, and visualized. DENV was isolated from six female Ae Aegypti collected from six pools (out of 259 pools). No other viruses were detected. Only five of the nine target localities had positive pools. Samples from the remaining four localities yielded negative results. Four DENV-positive mosquitoes were collected at the aquatic stages, and two were collected at the adult stage. These results show the circulation of DENV in adult mosquitoes and offspring, indicating vertical transmission of DENV. In conclusion, this study found that, in Makkah, DENV is circulating in dengue vectors with a high significance rate, suggesting the possibility of a dengue outbreak in the future; therefore, a sensitive surveillance system is vital to predict the outbreak and for early intervention and control.