The disease which was detected since May 1 this year is caused by a virus spread by mosquitoes, affecting mainly ruminants (cows, goats, sheep) and other wild animals, as well as human beings, the official statement said.
Cattle in the four affected districts including Ngoma, Kirehe, Kayonza and Rwamagana have been quarantined to prevent possible spread of the disease as efforts to control it are underway, veterinary reports said.
Meanwhile, teams of veterinary doctors have been deployed in the region to follow up in each of the affected districts where by some 1638 cows have so far received appropriate treatment.
The disease primarily infects livestock, but humans can catch the virus that causes it from mosquito bites or exposure to blood, raw milk or other fluids from infected animals.
Official reports indicate that no human cases has been reported so far in Rwanda, yet the number of affected livestock is thought to be much higher.
According to the Director General of Rwanda Agriculture Board (RAB), Dr Patrick Karangwa, the cause of the outbreak is unusually heavy rains, which have created ponds and lakes where mosquitoes can breed, in this region which is normally dry, reports said.
Rift Valley Fever is a viral zoonosis that can also infect humans.
"Most human infections result from contact with the blood or organs of infected animals”, Dr Karangwa said.