Alkhumra haemorrhagic fever virus (AHFV) is an emerging zoonotic pathogen which was first observed in 1995 in the blood of human patients in the Kingdom of Saudi Arabia.
Although the transmission of AHFV is not very well understood, the virus is believed to be transmitted to humans through tick bites, specifically from the Ornithodoros savignyi, Hyalomma dromedarii and Hyalomma rufipes species of tick. AHFV cases in humans have been epidemiologically linked to direct and indirect contact with the bodily fluids of livestock, namely cattle, sheep, goats, and camels, or through the consumption of raw infected milk. No human-to-human transmission of AHFV has been reported.
Since the first reported cases in 1995, several hundred cases of AHF have been documented in western and southern Kingdom of Saudi Arabia, as well as among tourists in Egypt, Djibouti and extending to India and parts of Europe. Cases appear to peak in the spring and summer months. However, due to the underreporting of human cases and the movement of animals it is possible the disease may have a wider geographical distribution than initially reported.
Clinical signs
After an incubation period of 2-4 days, patients infected with AHFV typically develop non-specific acute flu-like symptoms and in some case the disease may progress to a second, more severe, phase where patients can develop haemorrhagic and/or neurological symptoms. The case fatality rate of Alkhumra haemorrhagic fever (AHF) is reported to be up to 25% but it could be considerably lower due to underreporting of mild or asymptomatic cases in the few recorded outbreaks.
Symptoms include:
- Fever
- Severe headache
- Pain behind the eyes
- Muscle and joint pain
- Nausea/vomiting
- Abdominal pain
- Loss of appetite
- Diarrhoea
Severe haemorrhagic symptoms of AHF include:
- Nosebleed
- Bleeding from the gums
- Vomiting blood
- Black faeces and/or bleeding from the rectum
- Red or purple spots on the skin
- Bruising on the skin
Severe neurological symptoms of AHF include:
- Inability to think clearly
- Confusion/disorientation
- Dizziness
- Hallucination
- Stiffness in the neck
- Convulsions
- Sensitivity to light
Virology
It is a member of the Flavivirus genus and Flaviviridae family of viruses and contains a genome composed of single stranded positive-sense RNA within a capsid and a lipid envelope. To date, the virus has not been well documented in the scientific literature and there are no antiviral treatments or vaccines available.
Pirbright's research on Alkhumra haemorrhagic fever virus
We are carrying out research to investigate what mechanisms AHFV uses to cause disease, which could help in the development of antiviral treatments and vaccines against AHFV.
We are also studying what livestock species may be involved in transmitting and maintaining the virus to gain a better understanding of the risk of exposure.
Furthermore, we are combining this knowledge within a mathematical model to better understand what drives AHFV outbreaks so that preventative and control measures can be implemented during future outbreaks.
