Pathomorphology and pathogenesis of bacterial meningoventriculitis of neonatal ungulates.

The research investigates the origins and progression of bacterial meningoventriculitis, an inflammation of the nervous system and the brain tissue mainly occurring in newborn animals, particularly neonatal ungulates such as lambs or calves.

Study and Findings

• Bacterial meningoventriculitis was studied in 26 newborn ungulates (hoofed mammals) including species like calves and lambs.
• The researchers discovered that the disease often begins with a significant bacteremia, that is, bacteria presence in the bloodstream. The bacteria are usually of the Escherichia coli (E. coli) type.
• The subsequent inflammation, termed fibrinopurulent inflammation, primarily affects the leptomeninges (two inner layers of the brain covering), choroid plexuses (network of blood vessels in the brain), and walls of the ventricles (cavities in the brain), while, importantly, leaving the neuraxial parenchyma (brain tissue) largely untouched.

Proposed Explanation

• The researchers believe the particular pattern of disease progression, that is, the surface-relatedness of the symptoms is due to the transport of bacteria by specialized cells called monocytes having low bactericidal power. Meniginodentriculitis thus exhibits an unusual progression compared to other bacterial diseases.
• Monocytes, in their normal function, travel along established pathways supporting significant populations of macrophages (large white blood cells that absorb foreign particles) on our body surfaces, including the surfaces of the structures within our brains.
• The brain tissue or neuraxial parenchyma is typically spared of these damaging processes as it normally lacks a macrophage population. This explains why the inflammation does not spread to the brain tissues.

Further Implications

• The researchers hypothesize that a similar mechanism might be in place for the often concurrent appearance of serositis (inflammatory disease affecting the serous membranes), and synovitis (inflammation of the synovial membrane). Both conditions tend to occur alongside meningoventriculitis in newborn ungulates.