Stephanofilariasis refers to lesions of the skin of cattle in northern Australia caused by small filarial nematodes of the genus Stephanofilaria transmitted by the buffalo fly (Haematobia exigua).
The lesions are sometimes misdiagnosed as being solely from direct irritation of biting buffalo flies. Bos indicus are less affected than Bos taurus breeds.
L esions are unsightly, resemble ringworm and may cause rejection from export consignments. The lesions reduce value of hides for leather, and rubbing to relieve irritation may cause damage to infrastructure.
Lesions are circumscribed, hairless, slightly raised, dry and hyperkeratotic. Sometimes they are raw and weeping or cracked and scabby. They occur on the skin most commonly at the medial canthus of the eyes, the neck, sternum and occasionally the thorax and abdomen. The main differential diagnoses include ringworm, warts and dermatophilosis.
Laboratory confirmation requires a skin biopsy in buffered formalin for histology.
Repeated treatment with macrocyclic lactones (ivermectin, moxidectin) may cause significant reduction in size and number of lesions over weeks or months but some scars may be permanent.
Prevention relies on controlling buffalo fly on farm and treatment with macrocyclic lactones well ahead of time of export.