Chapter 17: Infections of the Nervous System and Sensory Structures

The chapter then explores neurotoxin-mediated diseases that cause severe neurological dysfunction through distinct mechanisms: tetanus results from Clostridium tetani producing tetanospasmin, which blocks inhibitory neurotransmitter release and causes rigid, generalized muscle contractions, while botulism from Clostridium botulinum toxin prevents acetylcholine release at the neuromuscular junction, producing flaccid paralysis. Viral infections are covered extensively, including poliomyelitis, which selectively damages motor neurons and leads to paralysis, and rabies, an acute encephalitis requiring immediate postexposure prophylaxis following zoonotic exposure. Arboviral encephalitides transmitted by arthropod vectors, particularly mosquitoes, are detailed with examples such as West Nile virus and Eastern Equine Encephalitis. The chapter addresses chronic peripheral nervous system involvement in leprosy, caused by Mycobacterium leprae, which progressively damages nerves and causes sensory loss. Infections in immunocompromised hosts receive dedicated attention, including opportunistic fungal infections such as cryptococcosis, protozoan infections including African and American trypanosomiasis, and prion diseases or transmissible spongiform encephalopathies exemplified by Creutzfeldt-Jakob disease, characterized by misfolded proteins that cause progressive neurodegenerative damage.