Bluetongue and related orbiviruses: overview of the world situation

BT is silently spreading in tropical and subtropical countries in the world. Serological surveys on BT in developing countries should be intensified and expanded. Research is needed to develop simplified virus typing techniques, to develop safe and effective vaccines and to establish procedures for differentiating BTV which produces clinical disease from that of low-virulency. It is considered necessary to develop a new disease reporting system which can accommodate both clinical and sub-clinical forms of BT. Knowledge on Ibaraki disease and EHD is limited. There is a need to intensify serological surveys in different parts of the world in order to grasp the global situation of these diseases and to plan strategies for them. To confine AHS in the south of the Sahara, the disease surveillance should be intensified in the Near East and northern Africa regions, and a stock of AHS vaccines for emergency use should be established.