•Certain occupational groups such as herders, farmers, slaughterhouse workers, and veterinarians are therefore at higher risk of infection
•As most human cases of RVF are relatively mild and of short duration, no specific treatment is required for these patients
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Health experts have explained why a human vaccine against Rift Valley Fever is yet to be found several years later.
The World Health Organisation says the virus was first identified in 1931 during an investigation into an epidemic among sheep on a farm in the Rift Valley.
It is a viral disease that primarily affects animals but can also infect humans, with Kenya having issued an alert after one case was reported in a human this month.
An inactivated vaccine has been developed for human use but is not licensed hence not commercially available.
Inactivated vaccines usually don’t provide immunity (protection) that’s as strong as live vaccines.
So you may need several doses over time (booster shots) to get ongoing immunity against diseases.
Benard Bett has noted that just like any other virus, it is very difficult to find treatment for RVF even though there are drugs which can be used on other viruses.
“There are few drugs which can be used for other viruses but I have not seen any drug that is used for RVF mainly because we know the biology of viruses; it mainly takes over the host cells so you can’t really target it passé,” Bett said.
Bett is an infectious disease epidemiologist at the International Livestock Research Institute (ILRI).
According to WHO, outbreaks of RVF in animals can be prevented by a sustained programme of animal vaccination.
Professor of virology at KAVI Institute of Clinical Research, University of Nairobi Omu Anzala explained that introducing any product into the market requires a rigorous process to ascertain its safety and efficacy.
"In 2001, when we started HIV vaccine work we actually thought by 2005, we would have a vaccine. 25 years later we don’t have a vaccine for HIV," Anzala said.
"Pathogens like these seem easy but when you get into the biology of understanding how they interact with the host and how they interact with the cells within the host that is where the challenge is," he added.
The virologist noted that even though there are products in the pipeline under development pathogens are not easy to study.
The WHO says the majority of human infections result from direct or indirect contact with the blood or organs of infected animals.
The virus can be transmitted to humans through the handling of animal tissue during slaughtering or butchering, assisting with animal births, conducting veterinary procedures, or from the disposal of carcasses or fetuses.
Human infections have also resulted from the bites of infected mosquitoes.
Certain occupational groups such as herders, farmers, slaughterhouse workers, and veterinarians are therefore at higher risk of infection.
As most human cases of RVF are relatively mild and of short duration, no specific treatment is required for these patients.
For the more severe cases, the predominant treatment is general supportive therapy.