Bovine herpesvirus meningoencephalitis in the State of Tocantins, Brazil

Three outbreaks of herpesvirus meningoencephalitis in cattle have been reported in three municipalities in the northern region of the State of Tocantins, Brazil. In one outbreak, 41 predominantly young bovines were affected, with 2-3 deaths in some cases. The animals showed neurological signs of incoordination, blindness, and recumbency, with death occurring within approximately 4-5 d. At necropsy, hyperemia and leptomeningeal hemorrhages were observed in the brain. Histology revealed more intense lesions in the rostral portions of the brain, mainly affecting the frontoparietal cerebral cortex, with nonsuppurative encephalitis and meningitis, glial nodules, neuronophagia, and eosinophilic intranuclear inclusion bodies in the astrocytes and neurons. This study shows the presence of bovine herpesvirus in Tocantins, probably the highly neurotropic type 5 strain, and emphasizes its importance in the differential diagnosis of bovine neuropathies.

An early clinical phenotype of necrotizing meningoencephalitis in the Pug reveals similarities to multiple sclerosis in humans

Necrotizing meningoencephalitis (NME) is a fatal neuroinflammatory disease that previously carried a uniformly grave prognosis. Our recent identification of a novel early form of NME in Pugs suggests that disease onset and progression are likely more insidious than previously recognized and provides new hope that early therapeutic intervention may halt disease progression and ultimately prevent or cure NME. This novel perspective also sheds new light on the clinical similarities to multiple sclerosis (MS) in humans and provides a rationale for cross-species translation. The history of recent scientific discoveries in NME and new parallels between MS and NME will be reviewed.

Application of metagenomic next-generation sequencing technique for diagnosing a specific case of necrotizing meningoencephalitis caused by human herpesvirus 2

Reactivation of latent human herpesvirus 2 (HHV-2) can cause spontaneous recovering aseptic meningitis and recurrent meningitis in adults, but it rarely affects the brain parenchyma to cause encephalitis. Here, we report the case of a 37-year-old male patient admitted to our hospital due to fever with a progressive headache for 3 days and paroxysmal episodes of unconsciousness for 1 day. Brain magnetic resonance imaging (MRI) revealed viral meningoencephalitis. Then, metagenomics next-generation sequencing (mNGS) was applied, which detected 12,024 unique sequences of HHV-2 in cerebrospinal fluid (2022), indicating HHV-2 encephalitis. After antiviral treatment, the patient’s symptoms improved, and he was discharged. During the 1-month follow-up, the patient recovered without any new symptoms, but a brain MRI revealed significant atrophy of the original foci. The patient was finally diagnosed with HHV-2 necrotizing meningoencephalitis, which is extremely rare. mNGS helped with the clinical diagnosis and strengthened our understanding of HHV-2 infections in the central nervous system.

Leukocyte and cytokine variables in asymptomatic Pugs at genetic risk of necrotizing meningoencephalitis

BACKGROUND

Necrotizing meningoencephalitis (NME, aka Pug dog encephalitis) is an inflammatory brain condition associated with advanced disease at initial presentation, rapid progression, and poor response to conventional immunomodulatory therapy.

HYPOTHESIS/OBJECTIVES

That genetic risk for NME, defined by a common germline DNA haplotype located on chromosome 12, is associated with altered blood cytokine concentrations and leukocyte subsets in asymptomatic Pugs.

ANIMALS

Forty Pug dogs asymptomatic for NME from a hospital sample.

METHODS

Prospective observational cohort study, including germline genome-wide genotyping, plasma cytokine determination by multiplexed profiling, and leukocyte subset characterization by flow cytometric analysis.

RESULTS

Seven (18%) dogs were high risk, 10 (25%) medium risk, and 23 (58%) low risk for NME, giving a risk haplotype frequency of 30%. High and medium risk Pugs had significantly lower proportion of CD4+ T cells (median 22% [range, 7.3%-38%] vs 29% [range, 16%-41%], P = .03) and higher plasma IL-10 concentrations than low-risk Pugs (median 14.11 pg/mL [range, 9.66-344.19 pg/mL] vs 12.21 pg/mL [range, 2.59-18.53 pg/mL], P = .001). No other variables were significantly associated with the NME haplotype-based risk.

CONCLUSIONS AND CLINICAL IMPORTANCE

These data suggest an immunological underpinning to NME and a biologic rationale for future clinical trials that investigate novel diagnostic, preventative, and therapeutic strategies for this disease.

Immune-Mediated Central Nervous System Disease-Current Knowledge and Recommendations

Immune-mediated inflammation is responsible for about 25% of central nervous system disease in dogs. The disease can affect all ages and breeds, but young to middle-aged small breed dogs are over-represented for most forms. Diagnosis consists of advanced imaging (MRI), cerebrospinal fluid analysis, and infectious disease testing, but biopsy is required for definitive diagnosis and classification of the disease into one of the many subtypes. Treatment consists of immunosuppressive medication with the goal being to control and/or improve clinical signs. Current literature shows that prognosis is variable.

Breed-Specific Magnetic Resonance Imaging Characteristics of Necrotizing Encephalitis in Dogs

Diagnosing necrotizing encephalitis, with its subcategories of necrotizing leukoencephalitis and necrotizing meningoencephalitis, based on magnetic resonance imaging alone can be challenging. However, there are breed-specific imaging characteristics in both subcategories that allow establishing a clinical diagnosis with a relatively high degree of certainty. Typical breed specific imaging features, such as lesion distribution, signal intensity, contrast enhancement, and gross changes of brain structure (midline shift, ventriculomegaly, and brain herniation) are summarized here, using current literature, for the most commonly affected canine breeds: Yorkshire Terrier, French Bulldog, Pug, and Chihuahua.

A study of experimental autoimmune encephalomyelitis in dogs as a disease model for canine necrotizing encephalitis

In the present study, the use of dogs with experimental autoimmune encephalomyelitis (EAE) as a disease model for necrotizing encephalitis (NE) was assessed. Twelve healthy dogs were included in this study. Canine forebrain tissues (8 g), including white and grey matter, were homogenized with 4 mL of phosphate-buffered saline for 5 min in an ice bath. The suspension was emulsified with the same volume of Freund's complete adjuvant containing 1 mg/mL of killed Mycobacterium tuberculosis H37Ra. Under sedation, each dog was injected subcutaneously with canine brain homogenate at four sites: two in the inguinal and two in the axillary regions. A second injection (booster) was administered to all the dogs using the same procedure 7 days after the first injection. Clinical assessment, magnetic resonance imaging, cerebrospinal fluid analyses, necropsies, and histopathological and immunohistochemical examinations were performed for the dogs with EAE. Out of the 12 animals, seven (58%) developed clinically manifest EAE at various times after immunization. Characteristics of canine EAE models were very similar to canine NE, suggesting that canine EAE can be a disease model for NE in dogs.