Occurrence of Q Fever at the Wildlife-livestock Interface of Amboseli Ecosystem, Kenya.

Abstract

Q fever is an important zoonotic disease caused by Coxiella burnetii which is an obligate intracellular bacterium. Domestic ruminants, mainly goats and sheep, are the main source of Q fever outbreaks in humans. Very scant data is available on the role and status of Q fever in wildlife in Kenya. Direct risks of Q fever include infection of humans and animals while indirect risks include loss of income from livestock due to reduced production and reproduction. This sero-epidemiological survey was conducted to investigate the proportion of animals with Q fever antibodies and associated factors of the disease in impalas, sheep and goats at the wildlife-livestock interface of Amboseli ecosystem in Loitokitok sub-county of Kajiado County, Kenya. Manyattas closest to the park were selected purposively since they would offer the best opportunity for wildlife-livestock interaction. A semi-structured questionnaire was also administered in all the households in selected Manyattas to gather general household data, owner/household head data, livestock production data and data on knowledge on Q fever and other zoonotic diseases in the study area. From twenty Manyattas, 200 sheep and 300goats (10 sheep and 15 goats in each Manyatta) were selected randomly. In addition, 20 impalas were conveniently captured through darting and net capture from inside the National Park. From each of the animals selected, 5ml of blood was collected through jugular venepuncture into plain vacutainer tubes for preparation of the sera. The blood was then left to stand for 1 hour in a cool box so as to clot slowly to form clear sera which was then transferred into well labelled cryo vials and stored in a refrigerator at -5°C before transport to the laboratory where it was stored at -20°C awaiting analysis. In the laboratory, the sera were tested for antibodies against Q fever using ELISA CHEKIT Q fever test kit (IDEXX, Westbrook, Maine, USA). Both optical density and percent positivity values were generated for sera antibodies.The association between serum antibody titres and the set of independent risk factors were tested through Fishers Exact Test and Mixed Logistic Regression. Data gathered in the study area using questionnaires showed that the knowledge on Q fever in the pastoral communities was very poor as all the interviewed animal owners had never heard of Q fever. However, other diseases such as foot and mouth disease, rabies, poxvirus and tuberculosis among others were well understood (71%) and the pastoralists took preventive measures such as boiling milk before drinking (100%), avoiding sharing sleeping quarters with animals (100%)and up to date animal vaccinations (86%). The sero-proportion of animals that tested positive for Q fever antibodies in impalas was 25% [95% confidence interval: 6%, 44%]. In sheep the sero-proportion was 6% [95% confidence interval: 2.7%, 9.3%] while goats sero-proportion was 21.7% [95% confidence interval: 17%, 26.4%]. Based on the results of Mixed Logistic Regression analysis, there was statistically significant association between species (p=0.007) and sero-positivity. There was no indication of confounding or interaction in any of the factors. This study showed the presence of Q fever antibodies in impalas, sheep and goats at the wildlife- livestock interface of Amboseli ecosystem which is rich in wildlife biodiversity that interacts with livestock, their owners and visitors, this interaction may result in zoonotic disease transmission.