NEWS Significant ecological variables of outbreaks of Risk Valley fever (RVF) in Kenya can be used to map risk zones of infectious disease both on a local and global scale as well as predict future outbreaks of the disease. This according to researchers at Umeå University among others in a study published in the International Journal of Infectious Diseases.
Researchers at Umeå University have, together with colleagues from the International Centre of Insect Physiology and Ecology in Nairobi, Kenya among others, identified the ecological factors increasing the risk of Rift Valley fever outbreaks in Kenya. The disease is mosquito-borne but can also be transmitted in direct contact between animals and humans or through direct contact with sick animals.
RVF causes huge outbreaks among humans and livestock in Africa and on the Arabian Peninsula, but there is also a risk of global spread, just like other mosquito-borne viral infections. RVF and similar infections can cause symptoms such as fever and muscle pains, and severe symptoms may include infections of the brain, haemorrhagic fever and liver problems. The mortality rate is estimated at approximately one per cent, but among the patients admitted to hospitals, up to 30 per cent can die as a result of the disease.
Livestock such as sheep, goats and cows are also heavily affected; mortality is high among young animals and the majority of infected pregnancies leads to abortions. The infectious disease has a very negative effect on economy in the affected areas as it often result in trade embargos.
In Kenya, outbreaks of Rift Valley fever has occurred several times. The research team from Umeå and Kenya can now show the ecological factors explaining the risk of an outbreak of the infectious disease. The results have led to a risk map of Rift Valley fever where certain Kenyan regions are at high risk of an outbreak.
The researchers studied how seven ecological variables affected the risk of an RVF outbreak for instance by analyzing satellite data observations, altitude above sea level, livestock statistics and soil ratio. The results showed that evapotranspiration, green vegetation and the livestock density were the factors that best explained the occurrence of RVF. This is probably directly connected with where the type of mosquitos spreading the virus likes to breed, as well as the closeness to large amounts of cattle that the mosquitos can bite and infect.
“Since we are now able to identify ecological variables important to the occurrence of RVF outbreaks, we can now map risk zones of the disease both on a local and global scale. The variables can also be used to predict and prevent future outbreaks and can hopefully be integrated in the system that is being established to warn about RVF outbreaks,” says Magnus Evander, Professor of Virology at the Department of Clinical Microbiology at Umeå University, and one of those in charge of the study.
Read the article in the International Journal of Infectious Diseases
Magnus Evander, Professor of Virology, Umeå UniversityPhone: +46 90-785 17 90
Email: magnus.evander@umu.se
The research in Umeå group consists of:
The research group in Kenya at the International Centre for Insect Physiology and Ecology (icipe) consists of:
Their research is a collaboration between Umeå and Kenya and has been funded by the Swedish Research Council and the Swedish International Development Cooperation (Sida).
Mosomtai G, M Evander, P Sandström, C Ahlm, R Sang, OA Hassan, H Affognon, T Landmann. Association of ecological factors with Rift Valley fever occurrence and mapping of risk zones in Kenya. International Journal of Infectious Diseases 2016 46: 49-55
Editor: Anna Lawrence