Primary amebic meningoencephalomyelitis caused by in a south-central black rhinoceros ().

A 20-year-old female south-central black rhinoceros () was evaluated because of an acute onset of CNS deficits. The rhinoceros had no history of illness. Clinical signs included acute lethargy, ataxia, and decreased appetite. Hematologic abnormalities included leukocytosis with neutrophilia and a profound left shift. Results of serum biochemical analysis revealed hypophosphatemia but no other abnormalities. Results of a quantitative PCR assay for West Nile virus and an assay for anti- antibodies in serum were negative; the patient was seropositive for multiple serovars. Antimicrobials and anti-inflammatory agents were administered, but the condition of the rhinoceros worsened overnight; despite treatment with additional anti-inflammatory and antimicrobial agents, IV fluids, and thiamine, it became obtunded and died of respiratory arrest ≤ 24 hours later. Necropsy revealed severe, diffuse, suppurative, and histiocytic meningo-encephalomyelitis involving the cerebrum, cerebellum, and spinal cord. Amebic trophozoites were observed on histologic examination of affected tissue. Infection with was confirmed by results of immuno-histochemical analysis and a multiplex real-time PCR assay. Findings suggested that south-central black rhinoceros are susceptible to the free-living ameba . Ameba-induced meningoencephalomyelitis should be considered as a differential diagnosis for rhinoceros that have an acute onset of neurologic signs. Diagnosis of infection in an animal has a profound public health impact because of potential human exposure from the environment and the high fatality rate in people with infection.