Summary
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.
Keywords
Amblyomma,
Geographic information system, Heartwater, Italy, Land use, Survival,
Temperature, Ticks.
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