Histopathologic spectrum and immunohistochemical diagnosis of amebic meningoencephalitis.

Traditionally, Naegleria fowleri infections are labeled primary amebic meningoencephalitis because of prominent meningeal neutrophilic inflammation. Acanthamoeba spp. and Balamuthia mandrillaris are labeled granulomatous amebic encephalitis because of parenchymal granulomatous inflammation. We compared histopathologic and immunohistochemical features of 18 cases with central nervous system free-living ameba infections. Immunohistochemical assays using polyclonal antibodies that reacted specifically against each genus identified 11 patients with Balamuthia infection, four with N. fowleri, and three with Acanthamoeba. Immunohistochemical assays highlighted the presence of trophozoites that were difficult to identify with hematoxylin and eosin stains in areas of necrosis or where macrophages were abundant. Immunohistochemical assays also demonstrated the presence of granular antigens inside macrophages and blood vessel walls. Amebic cysts were observed in three patients with Acanthamoeba infection and in three with Balamuthia. Patients with Acanthamoeba infection showed granulomatous inflammation. Patients with Naegleria infection had neutrophilic inflammation. Balamuthia infections showed a spectrum of inflammation that ranged from primarily neutrophils to granulomas. Meningitis was present in 88% of cases. Immunohistochemical assays were useful to demonstrate the presence of granular antigens and confirmed the genus of the ameba. The spectrum of inflammation in cases of Balamuthia meningoencephalitis is broader than previously described. The term amebic meningoencephalitis describes better the histopathologic findings than the currently used classification of primary amebic meningoencephalitis and granulomatous amebic encephalitis.

Clinical description of encephalopathic syndromes and risk factors for their occurrence and outcome during melarsoprol treatment of human African trypanosomiasis.

Encephalopathies are the most feared complications of sleeping sickness treatment with melarsoprol. To investigate the existence of risk factors, the incidence of encephalopathic syndromes and the relationship between the development of different types of encephalopathies and the clinical outcome was studied in a clinical trial with 588 patients under treatment with melarsoprol. The 38 encephalopathy cases were classified into three types according to the leading clinical picture: coma type, convulsion type and psychotic reactions. Nine patients were attributed to the convulsion type, defined as a transient event of short duration with convulsions followed by a post-ictal phase, without signs of a generalized disease. None of these patients died from the reaction. Febrile reactions in the 48 h preceding the reaction were generally not observed in this group. Twenty-five patients were attributed to the coma type, which is a progredient coma lasting several days. Those patients often had signs of a generalized disease such as fever (84%), headache (72%) or bullous skin (8%) reactions. The risk of mortality was high in this group (52%). About 14/16 patients with encephalopathic syndrome of the coma type were infected with malaria. Patients with psychotic reactions or abnormal psychiatric behaviour (3/38) and one patient who died after alcohol intake were excluded from the analysis. The overall rate of encephalopathic syndromes in the cases analysed (n=34) was 5.8%, of which 38.2% died. We did not find any parameters of predictive value for the risk of developing an encephalopathic syndrome based on the symptoms and signs before treatment initiation. The appearance during treatment of febrile reactions (RR 11.5), headache (RR 2.5), bullous eruptions (RR 4.5) and systolic hypotension (RR 2.6) were associated with an increased risk for the occurrence of encephalopathic syndromes especially of the coma type.