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Micro > Nervous System Diseases > Flashcards

Nervous System Diseases Flashcards

1
Q

microbial diseases of the NS

A
  • central and peripheral NS
  • CNS= brain and spinal cord
  • PNS = all nerves that branch off of the CNS; cranial and peripheral nerves
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2
Q

3 important functions of the NS

A
  1. sensory
  2. integrative
  3. motor
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3
Q

Defenses of the NS

A
  • mainly structural
  • bony casings
  • cushion of CSF
  • Blood-brain barrier
  • immunologically privileged site
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4
Q

Normal Biota of the NS

A
  • no normal biota

- any microorganisms in the PNS or CNS are a deviation from the healthy state

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5
Q

Meningitis
Encephalitis
Meningoencephalitis

A
  • inflammation of meninges
  • inflammation of the brain
  • inflammation of both
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6
Q

Most common Bacterial Meningitis

A
  • Neisseria meningitis
  • Streptococcus pneumoniae
  • Haemophilus influenzae
  • worldwide incidence
  • 3 types of bacteria cause 70% of bacterial meningitis
  • all 3 possess a capsule that protects them from phagocytosis
  • other bacteria may cause meningitis
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7
Q

Meningitis caused by Microorganisms

A
  • inflammation of the meninges
  • many different microorganisms can cause an infection
  • more serious forms caused by bacteria
  • Typical symptoms: headache, painful or stiff neck, fever and usually an increased number of WBC in the CSF
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8
Q

Diagnosis of meningitis

A
  • perform a spinal tap (lumbar puncture) to obtain cerebrospinal fluid
  • gram stain for morphology
  • Latex agglutination tests on CSF
  • prompt chemotherapy a must because of fast progress of disease
  • start w/ broad spectrum 3rd generation cephalosporins and adjust treatment as learn more about the isolate
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9
Q

meningitis

A
  • many different species of bacteria
    • Neisseria meningitis
    • Streptococcus pneumoniae
    • Haemophilus influenzae
    • Listeria monocytogenes

Fungi:

  • Cryptococcus neoformans
  • Coccidiodes immitis
  • Co or previous viral infections can facilitate meningitis
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10
Q

Hemophilus influenzae

A
  • gm neg. rod, aerobic
  • endotoxins; capsule
  • Hib vaccine caused decrease in occurrence
  • ear infections
  • respiratory route
  • sporadic cases
  • 6% mortality
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11
Q

Neisseria meningitdis

A
  • gm neg. coccus
  • endotoxins: released into circulation
    • activates WBC
    • cytokines released
    • damage to blood vessels
    • Petechiae develop
  • vascular collapse; hemorrhage; petechiae

-vaccine used in military and colleges
-epidemics
-death in a few hrs in severe cases
mortality 10%
-respiratory route

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12
Q

Petechiae

A

-pinpoint, round spots that appear on the skin as a result of bleeding under the skin

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13
Q

Streptococcus pneumoniae

A
  • gm pos. cocci
  • respiratory route
  • 26% mortality
  • vaccines have reduced incidence
  • common flora in nasopharyngeal region
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14
Q

Clostridium tetani

A
  • gm pos. rod, anaerobe, produces exotoxin
  • Neurotoxin which blocks the relaxation pathway of muscles; very potent toxin
  • tetanus called lockjaw
  • toxoid vaccine, booster every 10yrs
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15
Q

Tetanus

A
  • “rusty nail” tho to be the cause before bacteria discovered but now know that the spores of the organism can be found in the soil
  • newborns in developing countries contract tetanus when umbilical cord stump is exposed to spore
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16
Q

rabies virus

A
  • fatal encephalitis
  • long incubation period of weeks to months gives time for post-exposure immunization
  • bite, inhalation of saliva from injected skunk, bat, fox, raccoon
  • treat w/ antibodies and/or human diploid cell vaccine
  • identify infected animal w/ immunofluorescent study of the brain
  • look for negri bodies
  • Great Britain. Australia, New Zealand and Hawaii are free of rabies
  • Only strict vaccination policies keep countries rabies-free
17
Q

pathology of rabies infection

A
  1. virus enters tissue from saliva of biting animal
  2. virus replicates in muscle near bite
  3. virus moves up PNS to CNS
  4. virus ascends SC
  5. virus reaches brain and causes fatal encephalitis
  6. virus enters salivary glands and other organs of victim
18
Q

Leprosy (Hansen’s Disease)

A
  • Mycobacterium leprae
  • Acid-fast rod that grows best at 30C
    • very long generation time= 12days
    • cannot be grown on laboratory media. have not been able to provide the organism all the growth factors that it needs
    • grow organism in armadillos or in the footpads of nude mice
19
Q

Mycobacterium leprae

A
  • acid fast, slow grower in PNS (12 d gen time)
  • prefer cooler parts of body
  • not very contagious
  • grows in PNS and skin cells
  • transmission requires prolonged contact w/ an infected person
  • historically patients w/ leprosy were isolates but today they are treated at outpatients clinics w/ antibiotics which make them noncontagious
  • Tuberculoid (neural form): loss of sensation in ski areas; positive lepromin test
  • -lepromatous (progressive) form: disfiguring nodules over body, negative lepromin test
20
Q

Leprosy cases

A
  • 100-250 new cases in the US annually; most imported from tropical areas
  • half a million new cases worldwide
  • millions of ongoing cases worldwide: Asia, Africa, Brazil
  • combination of drugs used for 6-12 months depending on the stage of the disease: dapsone, rifampin and clofazimine
21
Q

Polio

A
  • highly infectious disease. invades the NS and can cause irreversible paralysis in a matter of hours
  • caused by the poliovirus
  • most people (90%) have no or mild symptoms
  • those w/ symptoms-include fever, fatigue, headache, vomiting, stiffness in the neck and pain in the limbs
22
Q

Spread of Polio

A
  • Direct person to person contact
  • contact w/ infected mucus from the nose or mouth
  • contact with infected feces
  • enters thru the mouth and nose, multiplies in the throat and intestinal tract, and absorbed and spread thru the blood and lymph system
  • develop symptoms of disease (5-35 days) *average 7-14 days)
23
Q

how does the virus infect the nerve cell?

A
  • Virus enters the central nervous system (the spinal cord and brain) either by traveling along peripheral nerves or via the circulatory system.
  • Virus shows attraction for nerve cells that control muscles
  • Poliovirus infects and destroys motor neurons, leaving virtually untouched adjacent nerve cells that control sensation, bowel movement, bladder function, and even sexual arousal.
24
Q

Polio: Acute flaccid paralysis (AFP)

A
  • one in 200 infections leads to irreversible paralysis, usually in legs
    • virus entering the blood stream and invading the CNS
    • virus destroys the nerve cells that activate muscles
    • affected muscles are no longer functional and the limb becomes floppy and lifeless- a condition known as acute flaccid paralysis (AFP)
25
Q

Polio: Bulbar polio

A
  • more extensive paralysis, involving the truck and muscles of the thorax and abdomen
  • most serious type, poliovirus attacks the nerve cells of the brain stem, reducing breathing capacity and causing difficulty in swallowing and speaking
  • among those paralyzed, 5-10% die when their breathing muscles become immobilized
26
Q

Post-polio syndrome

A
  • Around 40% of people who survive paralytic polio may develop additional symptoms 15–40 years after the original illness.
    • post-polio syndrome – include new progressive muscle weakness, severe fatigue and pain in the muscles and joints
    • Could be because the nerve pathways that took over after polio are now less active
27
Q

transmission of polio

A
  • An infected child passes live virus in the feces
  • Polio is spread through person-to-person contact, food and water
  • Poor hygiene, poor sewage treatment or poor latrines lead to transmission
  • Herd immunity prevents transmission
28
Q

Polio Vaccine: Salk vaccine: IPV

A
  • inactivated polio vaccine
  • not “live”; very safe
  • good protection from paralytic polio
  • does not provide strong protection in the gut
    • poliovirus can multiply in gut
    • excreted in feces and spread to other people
  • more expensive
  • used in developed countries where polio has been eliminated: cost benefit analysis
29
Q

Polio Vaccine: Sabin Vaccine: OPV

A
  • oral polio vaccine
  • easy to administer
  • inexpensive
  • good protection
  • multiples in gut and released in feces- “immunizes” others in contact
  • rarely causes paralytic polio in people
  • rarely mutates and become more like the wild type
  • not used in countries where polio has been eliminated
30
Q

endemic countries

A

Polio-endemic countries have never stopped transmission of wild poliovirus.

Afghanistan
Nigeria
Pakistan
India removed 2011

31
Q

countries with reestablished transmission of polio

A

Countries with re-established transmission have active and persistent poliovirus transmission of more than 12 months following an importation.
Angola
Chad
Democratic Republic of the Congo

32
Q

countries with imported poliovirus

A
  • Countries with imported poliovirus are experiencing ongoing outbreaks following an importation.
  • Congo, Liberia, Mali, Niger, Uganda, Kenya, Guinea, Gabon, Côte d’Ivoire, Central African Republic, China
33
Q

Polio virus types

A

Three types: Type 1, 2, 3

Type 2 poliovirus has been eliminated in the wild – the last wild type 2 poliovirus was detected in India in 1999.
-In this final stage of polio eradication, only type 1 and type 3 wild poliovirus continue to circulate in endemic areas. Both are highly infectious and both cause paralytic polio. Type 1 is the most pervasive strain of poliovirus, with type 3 highly localized in northern India, northern Nigeria, Pakistan and Afghanistan.

Micro (18 decks)

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