Chapter 22: Microbial diseases of the nervous system (Clostridium species, rabies, poliovirus)

Vocabulary-style flashcards covering Clostridium botulinum and tetani, endospores/vegetative form, rabies (capsid, transmission, incubation, symptoms), and poliovirus (transmission, iron lung, eradication progress, and related controversy).

Clostridium botulinum

Gram-positive, anaerobic bacillus that produces a highly potent neurotoxin causing botulism by inhibiting acetylcholine release at neuromuscular junctions, leading to flaccid paralysis; toxins can contaminate improperly canned foods; infantile botulism can result from honey exposure.

Botulinum toxin

One of the most potent toxins known; blocks acetylcholine release at neuromuscular junctions, causing flaccid paralysis; used medically for cosmetic and therapeutic purposes (e.g., Botox); effects last months requiring repeated injections.

Endospore

Dormant, highly resistant form produced by Clostridium; found in soil and released from the vegetative cell after germination; enables survival in harsh environments.

Vegetative cell

Metabolically active form of Clostridium that replicates inside the host and produces toxins after endospore germination.

Clostridium tetani

Gram-positive, anaerobic bacillus that causes tetanus; produces a neurotoxin leading to widespread muscle contractions (spastic paralysis), often with lockjaw; non-communicable.

Tetanus

Non-communicable disease caused by a neurotoxin that induces sustained muscle contractions; can be life-threatening and may fracture bones; preventable by vaccination.

Rabies

Lyssavirus with a distinct bullet-shaped capsid; transmitted mainly via bites from infected animals; travels to the CNS and then to the salivary glands for transmission; hydrophobia and CNS symptoms; almost always fatal once symptoms appear.

Bullet-shaped capsid

Distinct rabies virus morphology used for classification.

Incubation period (rabies)

Time from exposure to onset of symptoms; varies with bite location (shorter if bitten near the head/neck).

Hydrophobia

Fear of water due to painful swallowing in rabies infection, a common clinical feature.

Poliovirus

Picornavirus that causes poliomyelitis; acquired by ingesting contaminated water; can lead to irreversible paralysis and respiratory failure if respiratory muscles are affected.

Iron lung

Negative-pressure ventilator used to support breathing in poliomyelitis patients with respiratory paralysis; bulky but effective and historically common.

Poliomyelitis

Illness caused by poliovirus; range from asymptomatic to paralytic disease with possible death from respiratory failure.

Polio eradication progress

Number of polio cases has fallen by about 95% worldwide since 1988; many regions are polio-free, but complete eradication has not yet been achieved.

Poliovirus debate

Controversy over publishing methods to synthesize infectious polio virus and concerns about bioterrorism and public access to such information.