Natural Transmission of Heart-water of Sheep by Amblyomma variegatum (Fabricius 1794)

Abstract

The disease “Heart-water” of sheep, cattle and goats has been recognised in South Africa for upwards of 70 years, and as long ago as 1902 Lounsbury demonstrated the part played by the common bont-tick, Amblyomma hebraeum Koch 1844, in its transmission. The virus of the disease does not pass through the egg of the tick, but a tick infected in the larval or the nymphal stages is capable of transmitting the infection when feeding as a nymph or adult respectively. Further, according to Lounsbury, a tick infected as a larva may feed upon an insusceptible host during the nymphal stage, and still remain infective until the final feed as an adult.