HuangLongBing (HLB) originated in the 1900's in Asia where it is transmitted by the psyllid Diaphorina citri. In South Africa another form of HLB, transmitted by Trioza erytreae was described in the 1960's. The "African" and "Asian" forms may occasionally occur in a same area (Peninsula Arabia), where both species of the psyllids vectors are present, and each psyllid can carry both forms of the bacteria associated with HLB - Ca. L. asiaticus and Ca.L africanus. In the 2000's the arrival of HLB on the American continent re-boosted research on HLB. In Africa, after South Africa, HLB has caused severe damages in East Africa, mainly Kenya and Tanzania. Recently Ca. L asiaticus was identified in Ethiopia (1).On the west side, in Cameroon, syndrome of HLB was described and T. eythreae was present. This psyllid also invaded Madeira and the Canary Islands ten years ago. The Mediterranean basin produces around 18 million tons of citrus yearly. Because of the importance of movements, trade, tourism, pilgrims, Citrus production is in danger. The threat could come from the East (Saudi Arabia, Iran, Yemen) the South (Ethiopia, Somalia) and the West (Cameroon, Canarias). Cirad in collaboration with Embrapa -Brazil, Cameroon and partners in Morocco, Tunisia, Egypt and Turkey will start actions for a prevention strategy. A training curse on symptoms, psyllids identification and molecular diagnosis is scheduled on early 2011 and will be the foundation of an epidemio-surveillance network in the South Mediterranean basin. (Texte intégral)