Antemortem diagnosis of Borna disease (BD) in equids

Die Intra-vitam-Diagnose der Bornaschen Krankheit (BD) bei Equiden

Grabner A, Herzog S, Lange-Herbst H, Frese K

DOI: 10.21836/PEM20020612
Year: 2002
Volume: 18
Issue: 6
Pages: 579-586

In a retrospective study during a 14-year period (88-02) equids with Borna disease (n = 113) were evaluated. The goal of the study was to find the most reliable method for diagnosing BD by comparing antemortem and postmortem results. Serum, cerebrospinal fluid (CSF) and brain tissue were taken from horses (n = 97) and ponies (n = 12) of different breeds and age (between 6 months and 28 years). Furthermore, 3 donkeys and 1 mule were afflicted with BD. The animals lived in endemic areas mainly in Bavaria and other federal states of Germany (Baden-Württemberg, Hessen, Niedersachsen). Clinically, BD can be suspected with appropriate neurological signs and CSF results (nonsuppurative meningoencephalitis with mononuclear pleocytosis). In 86 out of 98 cases a diagnosis was based on the detection of BDV specific antibodies both in serum and CSF by indirect immunofluorescence assay (IFA). In all cases the diagnosis was confirmed by the detection of antigen and RNA in brain tissue. Therefore the sensitivity of the IFA method was 88 percent. False negative results (12 percent) occurred in peracute disease (n = 10) and in one horse at the beginning of an acute form of BD. Another horse was pretreated with corticosteroids. In these cases there might have been no production of antibodies mainly in the CSF but also in the serum or the antibody titer was to low for detection. In horses with inapparent BDV infection (n = 20) and with neurologic disease without BDV infection (n = 20) no false positive results were obtained. Therefore the specifity of the IFA method was 100 percent. The detection of RNA in peripheral blood mononuclear cells (PBMCs) by RT-PCR was not useful, since the results were negative in equids with BD (n = 27), in horses with inapparent BDV infections (n = 53) or in horses with neurological diseases without BDV infections (n = 95).