Post anti-rabies vaccine encephalitis presenting as acute psychosis: Case reports

Abstract

Rabies, an invariably fatal zoonotic disease, remains a major public health concern in resource-limited settings, where access to cell culture-derived vaccines constrained hampers comprehensive immunization programs and compromises effective disease control and prevention efforts. As a result, several countries, including Ethiopia, continue to utilize nerve tissue-derived vaccines (NTVs)-notably phenolized sheep brain formulations-despite their well-documented neurotoxicity and the global recommendation to transition to safer, cell culture-based alternatives. This report describes two clinically significant cases of severe neuroinflammatory syndromes temporally associated with the administration of nerve tissue-derived phenolized sheep brain rabies vaccine. The first involves a 50-year-old male who developed acute neuropsychiatric symptoms including agitation, confusion, hallucinations, ataxia, and profound sleep disturbances approximately two weeks after completing a full course of the nerve tissue anti-rabies vaccine. Magnetic resonance imaging (MRI) of the brain demonstrated bilateral, asymmetric hyperintensities on T2-weighted and FLAIR sequences involving the cingulate gyrus, basal ganglia, medial thalami, hypothalamus, and fornix, findings that are radiologically consistent with limbic encephalitis. The second case describes a previously healthy 4-year-old boy who experienced rapidly progressive quadriplegia, encephalopathy, and seizures following vaccination, with MRI findings characteristic of acute disseminated encephalomyelitis (ADEM), showing diffuse, symmetrical involvement of deep grey matter structures, brainstem, and cerebellar hemispheres. These cases show rare but serious central nervous system complications from nerve tissue rabies vaccines and highlight the urgent need to replace them with safer, WHO-recommended cell culture vaccines.

Keywords: Encephalitis; Nerve tissue vaccine; Psychosis; Rabies virus.

Fig. 1

Case −1 MRI axial fluid attenuated inversion recovery (FLAIR) image and (d) sagittal FLAIR images performed in February 2024 about one month post-rabies vaccination showing involvement of central gray matter, including the left pons, the centromedial thalami, and the right and left globus pallidus with possible limbic encephalitis.

Fig. 2

Case −2 the MRI with IV contrast, which showed diffuse and symmetrical bilateral basal ganglia, thalami, anterior temporofrontal lobe, midbrain, dorsal pones, and bilateral cerebellar hemispheric T1 hypo, T2, and FLAIR hyperintense signal changes that have no restrictions on DWI and no enhancement on post contrast with conclusion of the MRI finding was suggestive of acute demyelinating encephalomyelitis (ADEM).