Veterinary Handbook Disease Finder

Stephanofilariasis

Species

Other Names

  • Buffalo Fly Bite
  • Filarial Dermatitis

Syndromes

Description

Stephanofilariasis refers to skin lesions 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.

Lesions are unsightly, resemble ringworm, and may cause rejection from export consignments. The lesions reduce the value of hides for leather, and rubbing to relieve irritation may cause damage to infrastructure.

Clinical Signs and Diagnosis

Lesions are circumscribed, hairless, slightly raised, dry, and hyperkeratotic. They can be 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.

Treatment

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

Prevention relies on controlling buffalo fly on farm and treatment with macrocyclic lactones well ahead of time of export.