Amblyomma tick feeding in relation to host health.

The tick Amblyomma variegatum has been shown by field and controlled laboratory experiments to have a direct causal relationship with severe clinical dermatophilosis. The tick does not transmit the pathogen in the usual sense, either biologically or mechanically. The tick suppresses the immune system of the host, for unknown reasons, and this appears to enable the existing dermatophilosis to become a severe disease. There are other factors involved with the progression of dermatophilosis to clinical disease, such as malnutrition. However, the role of ticks is so distinct that it is likely that appropriate tick control using acaricide, when combined with other measures to improve the husbandry of the cattle, will reduce the incidence and severity of dermatophilosis.