North Africa: a regional overview of bluetongue virus, vectors, surveillance and unique features.

Bluetongue virus serotype 2 (BTV-2) appeared in North Africa in December 1999 and caused a total of 14 775 clinical cases and 1 286 deaths in sheep. This arthropod-borne viral disease was first reported by the Tunisian veterinary services in 1999 followed by the Algerian authorities in 2000 and has been described in adult sheep only. The overall morbidity and mortality rates were 9% and 3.5%, respectively. Following the initial incursion of BTV-2 in December 1999, Tunisia reported an epidemic in 2000 and a few outbreaks in 2002. Neither Morocco nor Libya has reported any clinical cases of bluetongue in recent years, despite surveillance programmes being carried out. In Tunisia, the control strategy was based on mass vaccination of sheep using a live-attenuated monovalent type 2 vaccine, while in Algeria, it was based on vector control. Vector surveillance has proven the presence of Culicoides imicola in Morocco but there are no data available for either Tunisia or Algeria.