On January 09, 2024, a suspected case of Rift Valley Fever (RVF) was detected in a 38-year-old female in Saku Sub-county, Marsabit County. The case was identified through the Acute Febrile Illness (AFI) surveillance system supported by the Centers for Disease Control and Prevention (CDC). The case, which was confirmed positive for RVF on January 18, 2024, and the additional reports of animal deaths in Marsabit and Wajir counties supported the likelihood of an outbreak. This triggered the county into an investigation into a potential outbreak. The Marsabit County Directorate of Veterinary Services dispatched a team to investigate the reported animal deaths in Saku Sub-county, where cases of animal deaths were also reported in North Horr Sub-county (towns of Mubisa, Karacha, Surr), along the route to Moyale subcounty, primarily affecting camels. Additionally, Eldas Sub-county in Marsabit reported camel and other animal deaths. These reports suggested a contiguous geographic area over which RVF cases might be occurring in Marsabit and Wajir counties.

Later in January 2024, the county of Marsabit Department of Health escalated their request for additional support to the Ministry of Health (national level) through the Division of Disease Surveillance and Response (DDSR). This prompted the Ministry of Health to deploy a multidisciplinary field investigation team comprising of Kenya Field Epidemiology and Laboratory Training Program (FELTP), the Division of Disease Surveillance and Response (DDSR) and CDC- Kenya to conduct an investigation in Marsabit and neighbouring Wajir County, to confirm and determine the magnitude of the outbreak, describe the epidemiology and clinical characteristics of the outbreak.

Additionally, the CDC-Kenya, in collaboration with the Kenyan Ministry of Health (MOH), is actively supporting the enhancement of the country's Integrated Disease Surveillance and Response (eIDSR) strategy through a data modernization initiative funded by the United States. As part of this initiative, CDC-Kenya is partnering with ICAP-Global Health, an implementing partner, to develop various digital solutions for the Division of Disease Surveillance and Response (DDSR). One of the key digital solutions developed under this initiative is the All Disease Outbreak Module (ADAM), designed to support DDSR as an outbreak management tool. ADAM facilitates the collection, analysis, and visualization of outbreak data, enabling rapid response and decision-making during disease outbreaks. The outbreak investigation in Marsabit County presented an opportunity to pilot the newly developed ADAM tool, demonstrating its effectiveness in supporting outbreak response efforts.

The investigation objectives included:

• Determine the magnitude and characterize the RVF outbreak in Wajir and Marsabit Counties.
• Characterize reported RVF-like syndromes in livestock in Wajir and Marsabit Counties.
• Conduct RVF joint risk assessment to evaluate national and county preparedness guided by the Contingency Plan.
• Identify potential risk factors associated with Rift Valley Fever in Wajir and Marsabit Counties.
• Institute prevention and control measures for RVF in affected areas.
• Pilot the All Disease Outbreak Module (ADAM) tool in Marsabit County.

The investigation confirmed the presence of an RVF outbreak in Wajir and Marsabit Counties. Other findings and recommendations from the investigation were disseminated to various stakeholders including the the Ministry of Health at both the county and national levels, and other stakeholders.

The investigation was carried out between January 24 – February 16, 2024.