A horse with Halicephalobus deletrix encephalitis in Italy.

A ninetee-year-old Belgian saddle-horse gelding was presented with a multifocal neurological syndrome. The horse showed a mild ataxia, circling to the right, inability to take food from the left side, left blindness, alternating hyperexcitability and depression, neck stiffness and profuse sweating. The history also reported a recurrent epistaxis. Rectal temperature was normal and no significant changes were indicated by haematological examinations. The horse was euthanized after 3 days of ill-ness. Results of gross necropsy revealed only a moderate interstitial nephritis and a progressive ethmoid haematoma. Histological examination of the brain revealed the presence of a disseminated meningo-encephalitis involving thalamus, mid-brain, right geniculate nucleus, pons and cerebelum. The lesions consisted in focal perivascular granulomatous inflammation with presence of nematodes with rhabditiform oesophagus. In the brain tissue they were always vascular oriented and associated with perivascular cuffing of lymphocytes and eosinophils, malacia, and presence of macrophages and multinucleatedcells. Spheroids in the affected areas were also observed. No parasites were detected in other organs. The histopathological features of the lesions and the morphology of the parasites are consistent with the infection with Halicephalobus (micronema) deletrix. This is the first case of H.deletrix encephalitis in Italy and consequently this infection should be considered in the differential diagnosis of equine encephalitides in our country.