Difference between lambs with chronic and mild dermatophilosis in frequency of alleles of CD3 gamma

Dermatophilosis (lumpy wool) in sheep: a review of pathogenesis, aetiology, resistance and vaccines

Lumpy wool (dermatophilosis) develops following prolonged wetting of sheep when bacterial proliferation in wool and on skin induce an exudative dermatitis, causing a superficial skin lesion and damage to wool follicles and fibres. The incidence of dermatophilosis is strongly dependent on wet and warm weather and, hence, infection is sporadic. While older animals are less at risk than are lambs, it is unclear whether this reflects naturally acquired immune resistance or the maturation of skin and wool fibres. Dermatophilosis directly causes wool production losses and it also is a risk factor for blowfly strike, which has a substantial economic impact and increasing challenges associated with current control procedures. This review assessed research on the bacterial causes of lumpy wool, the characteristics of the resulting immune defence reactions in sheep, current control strategies, and limitations of previous attempts to control lumpy wool by sheep vaccination.

Immune responses to Dermatophilus congolensis infections

Complex mechanisms underly the establishment of dermatophilosis, an exudative and proliferative skin disease of ruminants. This multicomponent system involves the bacterium Dermatophilus congolensis, transmission by various routes including flies, host genetic factors and immunosuppression by Amblyomma variegatum ticks. Here, Nick Ambrose and colleagues summarize recent evidence for an association between A. variegatum and severe chronic dermatophilosis in cattle. Breed-based differences in resistance to dermatophilosis are probably related to immunity to ticks or resistance to the immunosuppressive effects of ticks. Immunity to dermatophilosis might involve non-classic responses mediated by CD1 antigen presentation and gammadelta T cells. Progress towards vaccination is further complicated by strain-specific acquired immunity to D. congolensis.