Use of geographical information system and ecological niche model to analyse potential exposure of small ruminants to Coxiella burnetii infection in central Greece

Abstract

Seroprevalence of Coxiella burnetii in sheep and goats in central Greece was investigated. Objectives were: (i) to describe spatial distribution of sheep and goat exposure to C. burnetii in the study area, (ii) to identify environmental parametres related to C. burnetii exposure and (iii) to recognise high risk areas for sheep and goat exposure to C. burnetii. Blood samples were collected from sheep (n = 320) or goats (n = 80) in 20 farms, i.e. from 20 animals in each farm. Samples were examined for presence of antibodies against C. burnetii by using a commercial iELISA kit. Data on farms were located in the field using hand-held Global Positioning System Garmin units. Collected data were analysed by an Ecological Niche Model under the framework of a geographic information system. Nine sheep flocks and 2 goat herds were found to be ‘C. burnetii positive’ (55%) with C. burnetii antibodies detected in total in 46 sheep and 12 goats (14.5%). ‘C. burnetii positive’ farms were located in mean altitude of 282 m and mean distance from settlements of 919 m. The environmental variable with highest gain when used alone was animal density; the variable that decreased gain the most when omitted, was distance from farms. As areas with probability of >70% for exposure to C. burnetii according to the MaxEnt model, were recognised the central plain of Karditsa and Trikala regional units, located in low altitude zones and in irrigated and cultivated agricultural areas and pastures; in total, 37 human settlements are located in high-risk areas. © 2016 Elsevier B.V.