Canadian physicians help fight RVF in Kenya

Canadians can stake a claim in helping contain a major outbreak of a virulent new strain of Rift Valley Fever (RVF) that recently killed 150 Kenyans and 40 Somalis.

The virus is a mosquito-born pathogen that primarily affects livestock but humans can get infected through mosquito bites or contact with blood or other secretions from infected livestock, particularly during the slaughtering process. The virus also appears to be transmissable through raw milk.

But its spread was limited during the recent outbreak through a series of measures, such as restricting livestock movement, banning slaughters, wearing mosquito resistant clothing, using mosquito nets, and injecting vaccines in livestock, says Heinz Feldmann, head of the special pathogens program at the Public Health Agency of Canada's National Microbiology Laboratory in Winnipeg.

Feldman was 1 of 3 infectious disease specialists, along with Allen Grolla and Robbin Lindsay, whom PHAC dispatched to Kenya as part of an international effort to arrest the spread of RVF, for which there is no effective human vaccine. Canada also sent a mobile laboratory in aid of the World Health Organization-led initiative.

“We provided support in laboratory diagnostics as well as support in entomology/ecology,” Feldmann told CMAJ. “The support for the outbreak has discontinued but we will establish a presence in Kenya in the future to assist in outbreak and public health questions.”

The RVF virus causes hemorrhagic fever that is similar to Marburg and Ebola but is less virulent. Dr. Kariuki Njenga of the Centers for Disease Prevention and Control in the Kenyan capital of Nairobi, says the virus has not changed since it was first discovered in 1930, but changes in infection patterns are being tracked. The last major RVF outbreak occurred in 1997 during the El Nino rains, and killed more than 300 Kenyans. No outbreak outside sub-Saharan Africa was reported until September 2000, when cases were confirmed in Saudi Arabia and Yemen.

RVF in humans is characterised by fever, headaches and bleeding through the mouth and nose. The WHO says about 1–2% of those infected reach the severe hemorrhagic stage; and about half of those die. Feldmann said ribavirin treatment was used for such clinical cases but efficacy “was not really demonstrated.”