Hypersensitive immune response in the development of buffalo fly lesions in north Australian cattle

Buffalo flies (BF) (Haematobia irritans exigua) are major ectoparasites of cattle causing economic and welfare impacts in north Australian herds. They are extending their range southward. Skin lesions associated with BF feeding are manifested as focal dermatitis or ulcerated areas most commonly on the medial canthus of the eye, along the lateral and ventral neck, and on the abdomen. Lesion pathogenesis has been attributed to a filarial nematode, Stephanofilaria sp., transmitted by BF (Johnson et al. 1981), but recent findings have shown that infection with Stephanofilaria is not necessary for the development of BF lesions, and this together with the observed poor correlation between BF numbers and lesion development, suggests that other factors contribute to development of lesions (Naseem et al, unpubl. data). This study aimed to identify the role of cattle immune response in the pathogenesis of buffalo fly lesions.