Rabies

What are the specific cytoplasmic inclusions in neurons that serve as a diagnostic criterion for rabies called?

Specific cytoplasmic inclusions in neurons, which are a crucial diagnostic criterion for rabies, are called Babes-Negri bodies (or Negri bodies). They are intracytoplasmic oxyphilic (eosinophilic) rounded inclusions with basophilic granules about 10 nm in size. These structures are sites of production and accumulation of rabies virions in affected cells.

In which specific structures of the brain are Negri bodies predominantly localized?

Negri bodies are predominantly localized in the neurons of the cornu ammonis (hippocampus). In addition, for their detection during microscopic examination, material is sampled from the following brain structures:

• Pyramidal cells — located in the cerebral cortex.
• Purkinje cells — located in the cerebellar cortex.

What are the specific focal inflammatory infiltrates in rabies called, and what cells do they consist of?

Specific focal inflammatory infiltrates in rabies are called rabies nodules. They are lymphocytic infiltrates appearing around areas of affected cells.

Infiltration of perivascular spaces by lymphocytes and plasma cells with the formation of lymphoid "cuffs" around the brain venules is also described.

What is the pathogenesis of the hydrophobia symptom in rabies?

The pathogenesis of hydrophobia is due to increased reflex excitability, marked sympathicotonia, and damage to the neurons of the vegetative nuclei of the vagus (n. vagus) and glossopharyngeal (n. glossopharyngeus) nerves. Increased excitability of the higher autonomic centers creates a dominant focus that suppresses other stimuli. As a result, painful spastic contractions of the swallowing muscles and accessory respiratory muscles occur upon attempts to drink. As intensity increases, pharyngeal and laryngeal muscle spasms are triggered even by the mention of water or the sound of running liquid.

What macroscopic changes are found in the brain and its meninges during the autopsy of someone who died from rabies?

During the autopsy of a person who died from rabies, macroscopic changes in the brain and its meninges are characterized by scarcity. Edema and swelling of the brain tissue, as well as hyperemia, are detected. Moderate inflammation and mild neuronal destruction are observed. The stark contrast between severe neurological clinical presentation and sparse pathomorphology is explained by the fact that the virus causes functional impairments rather than neuronal death.

To which family and genus does the rabies causative agent belong?

The rabies causative agent (Neuroryctes rabid) belongs to the family Rhabdoviridae (rhabdoviruses) and the genus Lyssavirus (lyssaviruses). It is a neurotropic RNA-containing virus that causes an acute zoonotic transmissible disease with severe central nervous system involvement. This genus also includes related bat viruses that cause clinically indistinguishable diseases.