Members of this family of biting midges can be severe nuisances; they are also the vectors of two important animal diseases in Europe, bluetongue virus and African horse sickness. Culicoides biting midges are among the most abundant of haematophagous insects, and occur throughout most of the inhabited world. Across this broad range they transmit a great number of assorted pathogens of humans and domestic and wild animals, but it is as vectors of arboviruses, and particularly arboviruses of domestic livestock, that they achieve their prime importance. To date, more than 50 such viruses have been isolated from Culicoides species and some of these cause important diseases, particularly in animals (Mellor et al., 2000). As regards human infections in Europe, there has only been a single isolation of Tahyna virus from Culicoides species in Czechoslovakia (Halouzka et al., 1991). The group has no apparent importance as vectors of human disease in Europe; however, Culicoides are vectors of human diseases such as Oropouche virus in Brazil and vesicular stomatitis in the Americas, and surveillance of the activity of this group is necessary in Europe.

Haemoglobins in the midge family Chironomidae are potent human allergens and have been identified as causative allergens in asthmatic patients. Eriksson et al. (1989) concluded that Chironomidae might be allergens of clinical importance in asthma and rhinitis, in that cross-allergy exists between chironomids and shrimp and that cross-allergy also might occur among chironomids, crustaceans and molluscs.