Health

Rift Valley fever: a new rapid detection test

Results & impact 8 January 2020

A team from CIRAD has developed the first specific rapid detection test for Rift Valley fever (RVF), which primarily affects ruminants but can also be passed to humans. The possibility of identifying the virus instantly paves the way for more effective prevention of RVF epizootics like the one in Mayotte up to last summer.

The possibility of instantly identifying Rift Valley virus in animal blood samples has paved the way for better disease prevention © R. Carayol, CIRAD
The possibility of instantly identifying Rift Valley virus in animal blood samples has paved the way for better disease prevention © R. Carayol, CIRAD

The test, developed by a team at CIRAD Réunion, involves taking blood samples from sick animals, and it looks very promising. It makes it possible to detect the Rift Valley fever (RVF) virus (see box) in the field, right from the start of an epizootic (epidemic affecting animals).

"This rapid detection test identifies every strain of the RVF virus. It is based on antigen-antibody recognition, and enables early warnings of the disease", Catherine Cêtre-Sossah, one of the CIRAD researchers involved in developing the test, explains. "In December 2018, in Mayotte, the test was used to distinguish immediately between RVF and other diseases potentially responsible for high abortion rates in animals, such as peste des petits ruminants, leptospirosis or salmonella."

Rapid pen-side detection of the RVF virus

This instant diagnostic test can thus detect the virus as soon as it appears. Only level 3 containment laboratories could identify the virus up to now, and they will still be required to confirm the result.

However, along with the existing epidemiosurveillance networks, the test can be used to implement prevention and early warning measures to contain epizootics. Its sensitivity is due to be improved still further before its commercial launch, within the next two years. It could become a vital tool for controlling Rift Valley fever, and a patent application was lodged in France on 13 July 2018.

This study was funded by ERDF INTERREG V TROI 2015-2020 (European Union) and the Réunion Regional Council under the One Health Indian Ocean platform.

Rift Valley fever, a lethal zoonosis found in Africa and the Indian Ocean

Rift Valley fever (RVF) is a zoonotic virus that primarily affects ruminants (sheep, goats, cattle and camels), but can also affect humans. As its name suggests, it originated in the Rift Valley, and is found in West, southern and East Africa and in the Arabian Peninsula (see map). It can be lethal (in 1 to 5% of cases in humans).

The disease is mosquito-borne, and is fostered by outbreaks of the mosquito species concerned. It is a tropical disease, and can cause increased abortion rates in animals and greater mortality among young adults. It was restricted to Africa until the 2000s, but could eventually reach Europe via the spread of mosquito vector species, at least partly linked to global warming.

Key dates in the spread of Rift Valley fever

1930: Rift Valley fever virus described for the first time (Kenya)
1974: Epizootic in southern Africa (Namibia, Zambia and South Africa)
1977: RVF virus (RVFV) causes more than 600 human deaths (Egypt)
1987: First epizootic in West Africa (Senegal and Mauritania)
1997: Major epizootic in the Horn of Africa (Tanzania, Somalia, Kenya, Sudan)
2000: RVFV spreads to the Arabian Peninsula (Yemen and Saudi Arabia)
2006: Major epizootic in East Africa (Kenya, Sudan, Tanzania, Somalia)
2008: Epizootic in the Indian Ocean (Madagascar) and southern Africa (South Africa)
2018: Epizootic in Mayotte