Alkhurma haemorrhagic fever virus, an emerging tick-borne flavivirus with high fatality rate in Saudi Arabia

Abstract number: r2102

Charrel  R.N., Fagbo  S., Temmam  S., Zaki  A.M., de Lamballerie  X.

Alkhurma haemorrhagic fever virus (AHFV) has been first isolated in 1995 (reported in 1997) from patients presenting with either hemorrhagic fever or central nervous system manifestations. We present here a review of most of the cases reported to date in patients with emphasizing the clinical, biological and epidemiological data. Fatality rate is 25% which represents the most deadly flavivirus recognized at this time.

Objectives: 

To investigate the transmission routes of AHFV; to better understand the microevolution of AHFV in Saudi Arabia.

Methods: 

Ticks were collected in different regions of Saudi Arabia, identified using morphological keys and sequencing, and tested with Flavivirus generic primers. Biological material found to be positive by PCR amplification was sequenced for final identification, and used to attempt viral isolation onto Vero cells and/or via intracerebral inoculation to suckling mice.

Results: 

One tick (Ornithodoros savignyi) collected from a camel-resting place near the city of Jeddah was found to be positive for AHFV RNA. Full coding sequence of one isolate of AHFV (the first one to be detected in ticks) was determined and sequence analysis was performed for comparison with sequences derived from human specimens aiming at a better understanding of AHFV phylogeny and evolution. Different aspects of the potential transmission routes for AHFV will also be addressed. Field evidence for the tick-borne transmission of AHFV will be presented; Additional results provided by tick collection campaigns that are currently organized will be performed. Additional investigation of the microevolution will be presented based on human sequences determined in samples collected over the last 7 years.

Conclusions: 

Although AHFV is the most deadly flavivirus to circulate in the world, few investigation have been performed to date. In these times of surveillance of viruses candidate for bioterrorism use, a better knowledge of AHFV natural history and epidemiology is required, as well as a development of collaborative studies intending to field investigation of the medical, veterinary and entomological aspects.