Risk factors for serological evidence of MERS-CoV in camels, Kenya, 2016-2017

Middle East Respiratory Syndrome Coronavirus (MERS-CoV) is an emerging viral disease and dromedary camels are known to be the source of human spill over events. A cross-sectional epidemiological surveillance study was carried out in Kenya in 2017 to, 1) estimate MERS-CoV antibody seropositivity in the camel-dense counties of Turkana, Marsabit, Isiolo, Laikipia and Nakuru to identify, and 2) determine the risk factors associated with seropositivity in camels. Blood samples were collected from a total of 1421 camels selected using a multi-stage sampling method. Data were also collected from camel owners or herders using a pre-tested structured questionnaire. The sera from camel samples were tested for the presence of circulating antibodies to MERS-CoV using the anti-MERS-CoV IgG ELISA test. Univariate and multivariable statistical analysis were used to investigate factors potentially associated with MERS-CoV seropositivity in camels. The overall seropositivity in camel sera was 62.9 %, with the highest seropositivity recorded in Isiolo County (77.7 %), and the lowest seropositivity recorded in Nakuru County (14.0 %). When risk factors for seropositivity were assessed, the "Type of camel production system" {(aOR = 5.40(95 %CI: 1.67-17.49)}, "Age between 1-2 years, 2-3 years and above 3 years" {(aOR = 1.64 (95 %CI: 1.04-2.59}", {(aOR = 3.27 (95 %CI: 3.66-5.61)}" and {(aOR = 6.12 (95 %CI: 4.04-9.30)} respectively and "Sex of camels" {(aOR = 1.75 (95 %CI: 1.27-2.41)} were identified as significant predictors of MERS-CoV seropositivity. Our studies indicate a high level of seropositivity to MERS-CoV in camels in the counties surveyed, and highlights the important risk factors associated with MERS-CoV seropositivity in camels. Given that MERS-CoV is a zoonosis, and Kenya possesses the fourth largest camel population in Africa, these findings are important to inform the development of efficient and risk-based prevention and mitigation strategies against MERS-CoV transmission to humans.