In early 2024, a farmer's alarming arrival at the Marsabit County Referral Hospital marked the onset of a new outbreak of Rift Valley fever (RVF) in Kenya. He became the first confirmed human case in this latest surge of the zoonotic viral disease threatening not only human life but also the stability of livestock, particularly in pastoralist communities.

The RVF outbreak, particularly severe in Marsabit County near the Ethiopian border, is causing desperation among pastoralists. One such individual, Ali Hassan, recalled the catastrophic outbreak of 2006-2007 that forced him to evacuate his family from Garissa County after losing countless sheep, goats, and camels. “It’s a haunting memory,” he confessed, recalling the distress of affected pregnant animals bleeding and aborting. After witnessing RWF's resurgence in Garbatulla during 2020–2021, he had to relocate again to ensure his family's safety and livelihood.

What is Rift Valley Fever?

First identified during an investigation of an epidemic among sheep in Kenya's Rift Valley region back in 1930, RVF is a virus notorious for wreaking havoc among cattle, camels, and goats. Mosquitoes transmit the disease among animals but humans can contract it through direct or indirect contact with the blood or organs of infected livestock, often during veterinary care or butchering.

Over the decades, the reach of RVF has expanded significantly, with outbreaks reported in countries like Uganda, Sudan, Mauritania, and even as far as Saudi Arabia and Yemen. According to a 2021 review, RVF has been spreading not only in terms of geographical range but also in frequency—highlighting climate factors such as heavy rains and flooding that contribute to its recurrence.

Human and Animal Health Implications

Most human cases of RVF present mild flu-like symptoms; however, severe cases can lead to life-threatening conditions. The World Health Organization estimates that while fewer than 1% develop severe hemorrhagic fever, a significant minority can experience lasting neurological issues. Further complicating matters, RVF poses a severe risk to pregnant women, with Dr. Ibrahim K. Guyo of Isiolo County reporting that they are nearly five times more likely to suffer miscarriages compared to those uninfected.

“There’s also the risk of mother-to-child transmission of the virus,” emphasizes Dr. Guyo, who advises monitoring pregnant women closely in endemic areas.

Indirect Threats to Families and Communities

The repercussions of RVF are not limited to those directly infected. In pastoralist societies where livestock is vital for economic survival, outbreaks can decimate herds. Mortality among pregnant sheep can reach as high as 100%, significantly impacting families reliant on their livestock. “When RVF struck during the last outbreak from November 2020 to February 2021, we recorded 32 human cases and 11 deaths, heavily affecting male herders aged between 13 and 70,” a local vet recounted.

Edward Murimi, a veterinary extension officer in Isiolo, noted a concerning trend: “Outbreak cycles have shortened from ten years to every two or three years.” This trend aligns with climate indications that suggest worsening conditions will only increase the likelihood of future RVF resurgences.

Solutions and Preventive Measures

While vaccines for livestock exist, low awareness and nomadic lifestyles among pastoralists result in poor vaccination rates. A recent study highlighted that only 3.5% of surveyed farmers had vaccinated their animals against RVF despite the high mortality rates among livestock.

As for humans, a significant breakthrough may be on the horizon. A promising vaccine candidate has entered Phase II clinical trials in Kenya, the furthest stage any RVF vaccine has reached. This trial, involving 240 healthy adults, is a collaborative effort between the University of Oxford and the Kenya Medical Research Institute (KEMRI)-Wellcome Trust Research Programme.

Meanwhile, health officials are spearheading initiatives to raise awareness about RVF and available interventions, like recommending the use of gloves when handling sick livestock and promoting the clearing of potential mosquito breeding sites.

Conclusion: A Call for Vigilance

The growing threat of Rift Valley fever is a clarion call for immediate action. Both the public health system and pastoralist communities need to bolster their responses to this neglected tropical disease. With climate change accelerating the frequency of outbreaks, proactive measures are essential to protect both human and animal populations from future crises. Are we ready to confront the looming dangers of RVF, or will it catch us off guard once more?