micro chap 19

-occurs years after an intital measles episode
-seems to be caused by direct viral invasion of neural tissue

-transmissible spongiform encephalopathies (TSEs): neurodegenerative diseases with long incubation periods but rapid progression once they begin
-Human TSEs
*Creutzfeldt-Jakob disease (CJD)
*Gerstmann-Strussler-Scheinker disease
*fatal familial insomnia

-slow, progressive zoonotic disease
-characterized by fatal encephalitis
-average incubation time: 1-2 months or more
-prodromal phase begins with fever, nausea, vomiting, headache, fatigue, and other nonspecific symptoms
-two forms (both forms progress to the coma phase, resulting in death)

-periods of agitation, disorientation, seizures, and twitching
-spasms in the neck and pharyngeal muscles lead to hydrophobia

-patient is not hyperactive but is paralyzed, disoriented and stuporous

-acute enteroviral infection of the spinal cord
-can cause neuromuscular paralysis
-often affects small children
-most infections are contained as short-term, mild viremia
-some develop mild nonspecific symptoms of fever, headache, nausea, sore throat, and myalgia
-then spreads along specific pathways in the spinal cord and brain

poliomyelitis

-the virus infiltrates the motor neurons of the anterior horn of the spinal cord

poliomyelitis

-invasion but not destruction of nervous tissue

poliomyelitis

-various degrees of flaccid paralysis

poliomyelitis

-bulbar poliomyelitis

-also known as lockjaw
-Clostridium tetani
-gram-positive, spore-forming rod
-releases a powerful neurotoxin, tetanospasmin, that binds to target sites on peripheral motor neurons, spinal cord and brain, and in the sympathetic nervous system
-toxin blocks the inhibition of muscle contraction
-results in spastic paralysis
-first symptoms: clenching of the jaw, followed in succession by extreme arching of the back, flexion of the arms, and extension of the legs
-Risus sardonicus

-intoxication associated with eating poorly perserved foods
-can also occur as a true infection
-three major forms
-symptoms: double vision, difficulty in swallowing, dizziness; later symptoms include descending muscular paralysis and respiratory compromise
-Clostridium botulinum (spore forming anaerobe, releases an endotoxin- botox)

ingestion of preformed toxin

entrance of botulinum toxin into the bloodstream

-Trypanosoma brucei
-also called trypanpsomiasis
-affects the lymphatics and areas surrounding blood vessels
-usually a long asymptomatic period precedes onset of symptoms
-symptoms include intermittent fever, enlarged spleen, swollen lymph nodes, and joint pain
-central nervous system is affected with personality and behavioral changes that progress to lassitude and sleep disturbances