Ch. 18

Question 1

how does the blood-brain barrier protect the CNS?

Answer 1

• viruses invade easier than bacteria bc they are smaller
• blood vessel cells are sealed much more tightly in the areas around our CNS than they are in other areas of the body, the BBB allows only a few types of molecules to pass from capillaries into the CNS.

Question 2

listeria meningitis (listeriosis)

Answer 2

• listeria monocytogenes: gram-positive rods
• transmission: foodborne illness
  
  • healthy individuals: acute but short-lived
    gastrointestinal problems
  • elderly patients, immunocompromised
    individuals, neonates, and pregnant
    women – more serious
• bacterial meningitis

Question 3

what virus is considered an arbovirus?

Answer 3

• arboviral encephalitis and meningitis
• transmitted by arthropods

Question 4

clostridium botulinum

Answer 4

• anaerobe, produces neurotoxins, endospore
• transmission: found globally in soils and honey
  > endospores survive harsh conditions
  > canned vegetables
• botulinum toxin causes flaccid paralysis
  > infant botulism: children under 1 =
  immune system not matured. can move
  thru GI tract v easily
  > foodborne botulism: severe constipation=
  paralysis of GI tract
• prevention: children under 1 year old should not be fed honey. avoid improperly canned food
• treatment: administer antitoxins, breathing support, penicillin, clear out GI tract

Question 5

meningococcal meningitis

Answer 5

• neisseria meningitides: gram-negative aerobe, capsule (virulence factor for bact)
• 10% of population harbor this on their naval cavity
• symptom similar to those of other types:
  > rapid onset: fever, headache, stiff neck,
  vomiting
  > characteristic rash: bleeding, bruising
• treatment: abx; no treatment = fatal within hrs
• prevention: vax

Question 6

what is the cause of pneumococcal meningitis?

Answer 6

streptococcus pneumonia bacteria

Question 7

polio

Answer 7

• small, non-enveloped RNA virus
• transmission: fecal-oral
• signs and symptoms: flulike symptoms (few = paralysis phase)
• mechanism of disease: viral capsid protected from stomach acid
  > invades intestines
  > travel skeletal muscles
  > motor neurons to CNS
• complications: some experience paralysis (decreased w/ vaccines)
• recovery: 25% who recover will develop post-polio syndrome w/ deterioration of muscle fxn 10-40 years later

Question 8

prevention of polio

Answer 8

• salk (1957) – inactivated polio vax (IPV)
  > several boosters, used in US
• sabin (1963) – oral polio vax (OPV)
  > live, attenuated
  > not for immunocompromised; not used in US

Question 9

rabies

Answer 9

• characteristics: kill ~ 55,000 ppl worldwide every year
• transmission: classic zoonosis (animal bite)
• virus: ssRNA, RNA genome encodes 5 proteins=faster mutations
• progression: slowly replicate in muscle cells
• incubation period: 2-12 months
  > initial symptoms: fever, nausea, and paraesthesia around the wound (lasts 2-10 days)
• once neurological symptoms appear, it’s almost always fatal

Question 10

how do we treat rabies?

Answer 10

• rabies post-exposure prophylaxis
  > antirabies abys
  > inactivated (killed-virus) vaccine for rabies

Question 11

gut-brain axis

Answer 11

• describes the complex, back-and-forth communication that occurs between the endocrine, immune, and nervous systems and the gastrointestinal tract
• microbiome of human gut has some effect on the nervous system
• no natural microbiome in NS
• any disruption can lead to disease

Question 12

leprosy

Answer 12

• mycobacterium leprae: acid-fast bacillus
• transmission: resp. route
  > does not spread easily
  > armadillos: natural carriers

Question 13

2 forms of leprosy

Answer 13

• tuberculoid form: not as harmful; skin plaques associated w/ infected nerves and can cause local sensory loss
• lepromatous form: harmful bc it can spread to others and cause irreversible tissue damage and can be fatal if untreated

Question 14

Do viruses or bacteria more commonly invade the nervous system?

Answer 14

viruses bc they are smaller

Question 15

meninges

Answer 15

• three layers of tissue that surround the brain and spinal cord
• these layers support and care for the CNS by supplying nutrients, removing waste, and protecting the CNS from physical shocks

Question 16

What disease is considered nationally notifiable in all forms

Answer 16

• botulism