Eosinophil-associated inflammation and elaboration of eosinophil-derived proteins in 2 children with raccoon roundworm (Baylisascaris procyonis) encephalitis.

OBJECTIVE Eosinophil-associated proteins, especially eosinophil-derived neurotoxin, may be important contributors to the neurologic pathology and symptoms caused by Baylisascaris procyonis infection. METHODS Two cases of severe B procyonis encephalitis with evidence of marked eosinophil degranulation in the central nervous system are presented. Serial cerebrospinal fluid (CSF) specimens were collected from each patient during the course of their illness. Antibodies against B procyonis were measured in the patients' serum and CSF. Levels of the eosinophilopoietin interleukin-5 (IL-5) and 2 important eosinophil proteins, eosinophil-derived neurotoxin and major basic protein, were assayed in the CSF. RESULTS Both patients had rapidly progressive central nervous system disease with evidence of eosinophilic meningoencephalitis. Both tested positive for antibodies to B procyonis in serum and CSF and had progressively worsening deep white matter changes on magnetic resonance images of the brain. CSF levels of IL-5, eosinophil-derived neurotoxin, and major basic protein were markedly elevated over controls. CONCLUSIONS This is the first report of the measurement of IL-5, eosinophil-derived neurotoxin, and major basic protein in human CSF. In addition to traumatic damage and necrosis caused by migrating larvae, eosinophil-derived neurotoxin from associated eosinophilic inflammation may be an important contributory factor in the pathogenesis of B procyonis encephalitis. parasite, eosinophil-derived-neurotoxin, major basic protein, eosinophilia, hypereosinophilia, interleukin-5, encephalitis, child.