With the AGID, cross reactions with EHDV antibodies are common. For the detection of type-specific antibodies virus neutralisation tests are used. The adoption of International standard reference sera or the carrying out of interlaboratory comparisons is recommended in order to standardise laboratory results. EHDVs are a group of related and widely distributed orbiviruses, with at least eight serotypes. Domestic and wild ruminants can be infected, although clinical disease was originally described in deer.
Subclinical infections are common in infected areas.
EHDV-2 which have been shown to cause lesions in some species of domestic and wild ruminants are known to occur in America, Africa, Australia and Japan. For the detection of virus the methods recommended for BTV are used except that cell culture is more sensitive than intravenous inoculation of embryonated hens eggs. Certain AGID tests have been shown to lack complete group specificity and cross reactions with BTV antibodies may also occur. The northern and southern boundaries of BTV and EHDV infection around the world are determined by the presence of vector species of Culicoides, the distribution of which is controlled by climate. A distinct borderline between endemic, epidemic and free areas cannot always be drawn with certainty due to the movement of known vectors in response to climatic fluctuations and other environmental factors, and to the existence of less efficient potential vectors.