Chapter 2 - The history of bluetongue

Abstract

Research on bluetongue (BT) and more particularly on BT virus (BTV) has made spectacular progress in recent years. Bluetongue had already been known to sheep farmers in South Africa during the early part of the nineteenth century, most likely soon after the introduction of Merino sheep. However, the first detailed scientific descriptions of the disease in sheep were given by Hutcheon and Spreull. Bluetongue is historically an African disease, and although it has not been reported from all African countries, it is probably enzootic throughout the entire continent. Clinical recognition of the disease depends largely on the presence of highly susceptible European sheep breeds, which invariably act as indicators. It can be hypothesized that, historically, the primary epizootiological cycle of BTV involved species of African antelope and Culicoides midges. With the agricultural development of large parts of Africa, which led to wild ruminants being replaced by large numbers of domestic ruminants, the traditional epizootiological role of wild animals has largely been taken over by cattle. In regions such as southern Africa, the infection seems to progress in the cattle–midge cycle during spring and early summer, and once a certain level of infection is reached, it spills over to sheep. The continuous development of very powerful techniques will certainly contribute to novel approaches regarding diagnostic aids and vaccine development in the near future, which should greatly facilitate the control of BT.