The Sero-epidemiology of Coxiella burnetii in Humans and Cattle, Western Kenya: Evidence from a Cross-Sectional Study

Abstract

Evidence suggests that the intracellular bacterial pathogen Coxiella burnetii (which causes Q fever) is widespread, with a near global distribution. While there has been increasing attention to Q fever epidemiology in high-income settings, a recent systematic review highlighted significant gaps in our understanding of the prevalence, spatial distribution and risk factors for Q fever infection across Africa. This research aimed to provide a One Health assessment of Q fever epidemiology in parts of Western and Nyanza Provinces, Western Kenya, in cattle and humans. A cross-sectional survey was conducted: serum samples from 2049 humans and 955 cattle in 416 homesteads were analysed for C. burnetii antibodies. Questionnaires covering demographic, socio-economic and husbandry information were also administered. These data were linked to environmental datasets based on geographical locations (e.g., land cover). Correlation and spatial-cross correlation analyses were applied to assess the potential link between cattle and human seroprevalence. Multilevel regression analysis was used to assess the relationships between a range of socio-economic, demographic and environmental factors and sero-positivity in both humans and animals. The overall sero-prevalence of C. burnetii was 2.5% in humans and 10.5% in cattle, but we found no evidence of correlation between cattle and human seroprevalence either within households, or when incorporating spatial proximity to other households in the survey. Multilevel modelling indicated the importance of several factors for exposure to the organism. Cattle obtained from market (as opposed to those bred in their homestead) and those residing in areas with lower precipitation levels had the highest sero-prevalence. For humans, the youngest age group had the highest odds of seropositivity, variations were observed between ethnic groups, and frequent livestock contact (specifically grazing and dealing with abortion material) was also a risk factor. These results illustrate endemicity of C. burnetii in western Kenya, although prevalence is relatively low. The analysis indicates that while environmental factors may play a role in cattle exposure patterns, human exposure patterns are likely to be driven more strongly by livestock contacts. The implication of livestock markets in cattle exposure risks suggests these may be a suitable target for interventions.

The sero‐epidemiology of Coxiella burnetii (Q fever) across livestock species and herding contexts in Laikipia County, Kenya

“…For example, in West Africa looking at Fulani cattle herds (Adesiyun, Jagun, Kwaga, & Tekdek, ; Adesiyun, Jagun, & Tekdek, ), in the Adamawa region of Cameroon (Scolamacchia et al, ), in southeastern Ethiopia (Gumi et al, ), and in the Central African Republic (Nakouné et al, ) reported 32%–55%, 31%, 32% and 14% C. burnetii seroprevalence values, respectively. Within Kenya, two studies of cattle reported C. burnetii seroprevalence values of 28% and 11% (Knobel et al, ; Wardrop et al, ), but both of these studies were done in western Kenya in an area ecologically and economically very different from Laikipia.…”

“…Studies of cattle have found that proximity to water is a risk for C. burnetii infection and that seroprevalence in cattle correlates with precipitation levels (Czaplicki et al, ); (Ellen et al, ; Wardrop et al, ). West African sites reported higher antibody seroprevalence values than drier Sahelian regions (Adesiyun et al, ; Schelling et al, ), while wetter western Kenyan sites reported higher antibody seroprevalence values than Laikipia (Knobel et al, ; Wardrop et al, ).…”

“…Within Kenya, two studies of cattle reported C. burnetii seroprevalence values of 28% and 11% (Knobel et al, 2013;Wardrop et al, 2016), but both of these studies were done in western Kenya in an area ecologically and economically very different from Laikipia.…”

“…We found that animals in areas of mixed wildlife and livestock herding and in smallholder operations were the most likely to have been infected in the past. Contact with wildlife has been shown to be a determinant of similar infections in livestock in other contexts (Dahl & Hjort, 1976 Studies of cattle have found that proximity to water is a risk for C. burnetii infection and that seroprevalence in cattle correlates with precipitation levels (Czaplicki et al, 2012); (Ellen et al, 2009;Wardrop et al, 2016). West African sites reported higher antibody seroprevalence values than drier Sahelian regions (Adesiyun et al, 1985(Adesiyun et al, , 1984Schelling et al, 2003), while wetter western Kenyan sites reported higher antibody seroprevalence values than Laikipia (Knobel et al, 2013;Wardrop et al, 2016).…”

Seroprevalence and Factors Associated with Coxiella burnetii Infection in Small Ruminants in Baringo County, Kenya

“…A study in Laikipia County showed a distinct seroprevalence gradient, with seroprevalence ranging from 0% to 4% in cattle, 13% to 20% in sheep, 31% to 40% in goats and 5% to 46% in camels (DePuy et al., ). A recent linked human–cattle population survey in western Kenya detected prevalence of 2.5% in humans and 10.5% in cattle (Wardrop et al., ).…”