Meningoencephalitis and systemic infection by Acanthamoeba sp. in cattle in Brazil.

Abstract

Free-living amebas such as Acanthamoeba spp., Balamuthia mandrillaris, and Naegleria fowleri can cause infections in humans and animals. Here, we describe 2 cases of meningoencephalitis and an outbreak of multisystemic disease caused by Acanthamoeba sp. in cattle from Central-Western Brazil. Within 3 d of onset, 2 adult cattle from 2 different herds developed acute neurologic signs, including incoordination progressing to flaccid paralysis, opisthotonos, recumbency, and spontaneous death (case 1), and blindness, behavioral alterations, and flaccid paralysis leading to euthanasia (case 2). In a separate herd, 2 of 11 calves died within 5 d of developing lethargy and incoordination and were autopsied (cases 3, 4). On gross examination, the brains of all 4 cases and the cervicothoracic spinal cord of case 3 had red-brown areas of malacia and cavitation. Case 3 also had myriad firm, white, spherical nodules in the kidneys; case 4 had numerous firm, white lung nodules. Histologically, all animals had multifocal necrosis with granulomatous inflammation and numerous amebic trophozoites and cysts in the CNS. Lesions also included pyogranulomatous pneumonia, nephritis, myocarditis, and splenitis. Immunohistochemistry and PCR, followed by sequencing, confirmed Acanthamoeba spp. infection in all 4 cases. To our knowledge, Acanthamoeba sp.-associated encephalitis and multisystemic disease have not been reported previously in cattle.