Role of <i>Leishmania infantum</i> in Meningoencephalitis of Unknown Origin in Dogs from a Canine Leishmaniosis Endemic Area

Abstract

The main hypothesis for the aetiology of meningoencephalitis of unknown origin (MUO) in dogs is an autoimmune or genetic cause that is associated with a triggering event (environmental factors/infectious agents). The aim of this ambispective cohort study was to test for <i>Leishmania infantum</i> infection in the blood and cerebrospinal fluid (CSF) of dogs with MUO in an endemic area of canine leishmaniosis. Dogs with MUO were selected amongst all dogs undergoing blood anti-<i>L. infantum</i> antibody testing (control group). The blood plasma or serum samples from all dogs were analysed for anti- <i>L. infantum</i> antibodies by a quantitative indirect fluorescent assay (IFAT). In dogs with MUO, CSF samples were obtained for analysed by PCR detection of <i>L. infantum</i> DNA. Forty-four percent and 22% of the dogs in the MUO group featured magnetic resonance imaging (MRI) findings and CSF cytology respectively, consistent with <i>L. infantum</i> infection. IFAT, PCR, and histological findings were negative for <i>L. infantum.</i> A significant difference in <i>L. infantum</i> infection prevalence was found between the control and MUO group (<i>p</i> = 0.0022). While it seems unlikely that <i>L. infantum</i> plays a role in the aetiology of MUO, in endemic areas, this pathogen should be included in the differential diagnosis of this neurological disorder.