The systemic effect of adult and immature Amblyomma variegatum ticks on the pathogenesis of dermatophilosis.

The systemic effect of adult and nymphal Amblyomma variegatum on the pathogenesis of experimental infections of Dermatophilus congolensis was investigated. Three groups of four sheep were used with all 12 sheep being infected with identical titrated doses of D. congolensis One group of sheep was simultaneously infested with adult A. variegatum the second with nymphal A. variegatum and the third group were the controls, with no exposure to ticks. Assessment of the resulting infections indicate that the systemic effect of this tick is confined to the adults. Skin and serological tests using foreign antigens showed significantly reduced cell mediated and humoral immune response only in the sheep infested with adult A. variegatum.