Amoebic meningoencephalitis caused by Balamuthia mandrillaris in an orang utan.

摘要

The case of a 20-year-old male orang utan (Pongo pygmaeus) who developed acute onset depression, lethargy, inappetance and apparent head pain is reported. The animal was considered to have a systemic manifestation of an ongoing respiratory disease (Pseudomonas spp. including P. aeruginosa were cultured from a mild air sac discharge) and was treated with enrofloxacin (5 mg/kg orally, once daily). The treatment was changed 4 days later to a syrup preparation of 1000 mg amoxycillin and 250 mg clavulanate (twice daily). By the 7th day the animal had become ataxic and disorientated and he died on the 9th day of the illness. Although a brain abscess was suspected as the cause of death, necropsy and brain sectioning revealed the presence of multiple circular, soft, white-grey brown areas of varying size. The largest areas were in the left temporal (3.5 cm diameter) and right occipital (2.5 cm diameter) regions of the cerebrum. Histological sections stained with haematoxylin and eosin revealed many amoebic trophozoites and occasional cysts associated with areas of haemorrhage and inflammatory necrosis. The trophozoites were packed in perivascular spaces and their nuclei often contained 2 or more prominent nucleoli. Amoebae were not detected in sectionsof the air sac and lung. The cytological features of the trophozoites and cysts were characteristic of both Acanthamoeba spp. and Balamuthia mandrillaris. Indirect immunofluorescent labelling of histological sections suggested that the agent was B. mandrillaris. It is concluded that B. mandrillaris should be considered amongst the causes of acute onset meningoencephalitis in animals.