Exposure patterns and the risk factors of zoonotic Crimean Congo hemorrhagic fever virus amongst pastoralists, livestock and selected wild animals species at the human/livestock/wildlife interface in Isiolo County, upper eastern Kenya

Crimean Congo hemorrhagic fever (CCHF) is a tick-borne zoonotic disease caused by CCHF virus (CCHFV), and has a complex transmission cycle that involves a wide range of hosts including mammalian and some species of birds. We implemented a seroepidemiological study in Isiolo County, Kenya, to determine relative seroprevalences of CCHFV in pastoralists, livestock and in wild animals' species. In addition, we identified subject and environment level factors that influence exposure to CCHFV. Pastoralists (n = 580) and livestock (n = 2,137) were recruited into the study through a multistage random sampling technique, and addition, various species of wild animals (n = 87) were also sampled conveniently. Serum samples from all recruited subjects were collected and screened for CCHFV antibodies using ID.vet multispecies, double-antigen IgG enzyme-linked immunosorbent assay (ELISA). The overall anti-CCHFV IgG seroprevalences in pastoralists, cattle, goats, sheep and camels were 7.2% [95% CI: 3.1–15.8%], 53.9% [95% CI: 30.7–50.9%], 11.6% [95% CI: 7.2–22.5%], 8.6% [95% CI: 3–14%] and 89.7% [95% CI: 78–94%], respectively. On average, wild animals' hosts had CCHFV seroprevalence of 41.0% [95% CI: 29.1–49.4%], and giraffes had the highest seroprevalence of 75.0% [95% CI: 63.2–79.3%]. Analysis using mixed effects logistic regression models showed that CCHFV exposure in pastoralists was significantly associated with male gender, being over 30 years and belonging to a household with a seropositive herd. In livestock, mature animals, high normalized difference vegetation indices and high vapour pressure deficit were significantly associated with CCHFV exposure. Age, sex and species of wild animals were considered as the risk factors in the analysis, but none of these variables was significant (P-value = 0.891, 0.401 and 0.664 respectively). A look at the risk factors suggests that the environmental factors such as the NDVI (P-value = 0.032) and the vapour pressure deficit (P-value = 0.004) significantly influences CCHFV exposure in livestock, while the presence of infected animals in a household significantly influences pastoralists exposure (P-value = 0.041). CCHF control in livestock, for example by applying acaricides, could minimize the risk of CCHFV exposure to pastoralists. The key findings of this study will guide policymakers in disease control, and emphasize the need for regular surveillance of zoonotic diseases for emergency preparedness, and also contributes to knowledge on One-Health approach for improved health. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This research was generously supported by the Defense Threat Reduction Agency under Grant No. HDTRA11910031. It is imperative to emphasize that any opinions or findings presented here do not necessarily reflect the stance or policy of the federal government, and no official endorsement should be inferred. In addition, we would like to express our appreciation to the donors of the CGIAR Fund (https://www.cgiar.org/funders), whose contributions have been instrumental in advancing agricultural research worldwide. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study received ethical approval from the Institutional Research Ethics Committee of the International Livestock Research Institute (Reference number: ILRI-IREC2020-07) to collect samples from both livestock and humans I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data is completely available without any restrictions. Kindly contact the corresponding author at euginemukhaye17@gmail.com for all data requests.