INFECTIOUS DISEASES: NERVOUS SYSTEM (Ch. 20)

2 major nervous system divisions

CNS (brain + spinal cord) & PNS (nerves).

Meninges

Protective membranes around CNS — dura, arachnoid, pia.

CSF

Cerebrospinal fluid; normally sterile.

Blood-brain barrier (BBB)

Restricts pathogen entry; makes treatment difficult.

Meningitis definition

Inflammation of meninges.

Meningitis symptoms

Fever, headache, stiff neck, nausea, photophobia.

Serious complication of meningitis

Can be rapidly fatal.

Diagnosis of meningitis

Lumbar puncture → CSF analysis.

Bacterial vs viral meningitis severity

Bacterial = more severe; viral = milder.

Gram stain + shape of Neisseria meningitidis

Gram- diplococci.

Transmission of Neisseria meningitidis

Respiratory droplets.

Key feature of Neisseria meningitidis

Endotoxin → rapid shock.

Symptoms of Neisseria meningitidis

Sudden fever, headache, petechiae.

Is there a vaccine for Neisseria meningitidis?

A: Yes

Streptococcus pneumoniae gram stain + shape

Gram+ diplococci.

Most common cause in adults?

Yes

Capsule importance

Major virulence factor.

Is there a vaccine for Streptococcus pneumoniae?

A: Yes (PCV).

Haemophilus influenzae (type b) Gram stain

Gram- coccobacillus.

Haemophilus influenzae (type b) prevented by?

A: Hib vaccine.

Listeria monocytogenes Transmission

Foodborne — refrigerated foods.

Risk groups of Listeria monocytogenes

Pregnant women, neonates, elderly.

Listeria monocytogenes able to grow at?

Cold temps.

VIRAL MENINGITIS most common cause

Enteroviruses

Severity of viral meningitis

Usually mild; self-limiting.

ENCEPHALITIS

Inflammation of brain tissue.

Symptoms of encephalitis

Behavioral changes, confusion, seizures.

Most common cause of encephalitis

Arboviruses (mosquito-borne). Examples: West Nile virus.

RABIES Causative agent

Rabies virus.

Transmission of rabies

Bite → saliva of infected animal.

Pathogenesis

Virus travels via nerves → brain → fatal.

Pathogenesis Symptoms

Hydrophobia, agitation, paralysis.

Pathogenesis Prevention

Post-exposure vaccine + immune globulin.

TETANUS Causative organism

Clostridium tetani.

Tetanus Gram +, spore-forming rod — location?

Soil; anaerobic.

Tetanus Toxin

Tetanospasmin → blocks inhibitory neurotransmitters.

Tetanus Symptoms

Muscle spasms; lockjaw.

Tetanus Prevention

DTaP/Tdap vaccine.

BOTULISM Causative organism

Clostridium botulinum.

Botulinum Toxin

blocks acetylcholine release.

Botulinum Toxin results in

Flaccid paralysis.

Botulinum Toxin Sources

Improperly canned foods; infant botulism from honey.

POLIO Causative agent

Poliovirus.

Polio Target

Motor neurons

Polio Results

Paralysis

Polio Prevention

Vaccination (IPV).

ARBOVIRUSES Transmission

Arthropods (mosquitoes).

Arboviruses Diseases

Encephalitis; West Nile virus.

Prion

Misfolded protein that causes neurodegeneration.

Prion Diseases

Creutzfeldt-Jakob disease; mad cow disease.

Prion Transmission

Contaminated tissue (brain/spinal).

Prion Treatment

None; fatal.

Rabies reservoir

Bats, raccoons, skunks, foxes.

Tetanus reservoir

Soil

Best diagnostic test for meningitis

Lumbar puncture → CSF.

Bacterial CSF

High neutrophils, high protein, low glucose.

Viral CSF

High lymphocytes, normal glucose.