The historical background and global importance of heartwater.

The first written record of what probably could have been heartwater originates from South Africa and dates back to 1838. Since then, the disease was described from almost all the African countries south of the Sahara as well as from Madagascar, São Tome, Reunion, Mauritius and a number of islands in the Caribbean. Most research on the disease, at least until recently, was conducted in South Africa. Progress in research was slow but a few outstanding findings are mentioned in this paper. Despite inadequate information on its actual economic impact on livestock production, it is generally accepted that heartwater is either the most or second most important tick-borne disease in Africa. Depending on the area, heartwater ranks either second or third amongst diseases such as East Coast fever, tsetse-transmitted trypanosomiasis, rinderpest and perhaps also schistosomiasis. Heartwater is a major obstacle with regard to the introduction of highly producing animals intended for the upgrading of local breeds. Furthermore, it remains a major threat to areas such as the American mainland, where potential vectors are present but where the disease does not occur.