Dengue Fever Emerges in Egyptian Resort City, Raising Global Health Concerns
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researchers documented four confirmed cases of dengue fever in travelers returning too Israel between April and June 2024, all after visiting Sharm El-Sheikh, a popular desert resort city in South Sinai, Egypt. This location had not previously been identified as a dengue transmission area, and the arid environment of the Sinai Peninsula was thought to be unsuitable for the Aedes mosquitoes that carry the virus.
The cases were unrelated, with differing travel dates and accommodations spread across 3-25 kilometers. All patients experienced typical dengue symptoms – fever, headache, muscle pain (myalgia), and rash – and required hospitalization for supportive care. One patient experienced meningeal irritation,but cerebrospinal fluid testing was unremarkable,although DENV-2 RNA was detected. Serum testing confirmed DENV-2 infection, with some cases also showing evidence of nonstructural protein 1 antigen and IgM/IgG antibodies.
Genomic Analysis Points to Pakistan Origin
To understand the origin of the infections, researchers performed whole-genome sequencing of the virus. Analysis revealed that the DENV-2 strains clustered within the Cosmopolitan genotype, forming a distinct group differing by 32 mutations from the nearest known global strain. Notably, the closest related sequences were identified in Pakistan.
“The genetic data strongly suggests a single outbreak, with the virus likely originating from Pakistan,” explained a senior researcher involved in the study. The only publicly available sequence from a geographically close location – the United Arab Emirates in 2023 – clustered separately, highlighting the lack of regional surveillance data.
Red Sea as a Potential Transmission Corridor
The findings align with reports of DENV-2 spread along the Red Sea and recent cases identified in Florence, Italy. Over the past two decades,populations of Ae. aegypti mosquitoes have expanded along the Egyptian Red Sea coast, correlating with dengue outbreaks. While no entomological data currently exists for the Sinai Peninsula, the clustering of cases in Sharm El-Sheikh suggests potential local adaptation within urban microhabitats.
Maritime and air travel are likely contributing to the introduction of both mosquitoes and the virus into the Red Sea region.The pattern of outbreaks in Red Sea port cities suggests that maritime transport plays a key role in the spread. Specifically, daily ferry services from Hurghada, where dengue has recently emerged, to Sharm El-Sheikh may be facilitating transmission.
Genetic data from outbreaks in Jizan, Saudi Arabia (2019) and strains collected between 1992-2014 further indicate multiple introductions linked to a DENV-2 variant similar to strains found in Malaysia, Singapore, Korea, and China. Analyses of Saudi Arabian strains reveal a strong connection to viruses from countries contributing large numbers of Hajj and Umrah pilgrims,including Indonesia,Pakistan,and India.
Urgent Need for Enhanced Surveillance
This report of four cases within a three-month period in different locations within Sharm El-Sheikh suggests sustained DENV-2 transmission. Researchers emphasize the critical need for enhanced vector surveillance and control measures, and also increased public health awareness. The genetic data generated in this study can help address gaps in regional DENV sequence reporting and improve understanding of the virus’s molecular epidemiology and origins.
Dr. Zuckerman leads the Bioinformatics and Genomics Center at Israel’s Central Virology Laboratory, Ministry of Health, and is affiliated with Tel Aviv University’s School of Public Health. Her work focuses on genomic surveillance, molecular epidemiology, and bioinformatics applications in the study of viral pathogens.
