Use of geographic information systems to identify areas at risk of introducing Amblyomma variegatum and A. hebraeum to Italy

Abstract

Tick-borne diseases are one of the most important obstacles to the development of livestock breeding in Africa. Among these diseases, heartwater is of significant importance, second in rank to East Coast fever. Heartwater affects wild and domestic ruminants and is caused by a micro-organism belonging to the order Rickettsiales, previously called Cowdria ruminantium and recently renamed Ehrlichia ruminantium. The disease is transmitted solely by ticks. Although the aetiology and the clinical signs have been known for a long time, epidemiology presents many aspects that have yet to be understood. Among these, the biology of the vectors, ticks of the genus Amblyomma, present many features linked to environmental conditions that affect the likelihood of disease occurrence in free countries. Sporadic reports of the presence of Amblyomma variegatum in the Mediterranean are probably due to the introduction of these ticks by migratory birds. A predictive geographic information systems (GIS) model was built using temperature and land use as predictors that influence the risk of survival in Italy of infected Amblyomma ticks possibly carried by migratory birds. The model predicts Sardinia, Sicily and the south-western part of the Italian peninsula as being the most suitable areas for the presence of A. variegatum and A. hebraeum presence. The use of GIS could be an effective tool to estimate the risk of introduction and establishment of infected Amblyomma ticks.