TB and prions (exam 2)

Question 1

what is the leading cause of death worldwide?

Answer 1

tuberculosis (global emergency)

Question 2

how much of the worlds population is infected with latent TB?

Answer 2

1/4

Question 3

what is the issue with antibiotics for TB?

Answer 3

6-9 month drug course => issue with compliance, affordability, access

Question 4

Mycobacterium tuberculosis

Answer 4

• aerobic
• gram-positive
• non-motile
• no outer cell membrane (have to acid-fast stain)
• cell wall is thicker than most (hydrophobic)

Question 5

why is mycobacterium tuberculosis difficult to culture?

Answer 5

it is slow growing (24 hours)

Question 6

mycobacterium tuberculosis complex

Answer 6

8 (sub)species form complex and cause human disease

Question 7

what protects the bacilli of TB?

Answer 7

waxy outer coat

Question 8

what are the two front line antibiotics used for primary infection of TB?

Answer 8

isoniazid (INH) and rifampin (RIF)

Question 9

what is the antibiotic therapy recommended for primary active TB disease?

Answer 9

antibiotic combination for 6 to 9 months

rest, good diet

Question 10

why is TB re-emerging?

Answer 10

• TB and HIV co-infection (HIV victims are 800 times more likely to develop active TB)
• Multiple Drug-Resistant (MDR) and Extremely Drug-Resistant (XDR) TB
  MDR are resistant to INH and RIF (rifampin); XDR resistant to multiple treatments
• complacency
• travel and immigration

Question 11

what is the vaccine for TB?

Answer 11

BCG (bacillus Calmette-Guerin) vaccine

• attenuated (weakened)
• protection rate is 80% for children and <50% for adults
• protection is not life long (5-15 years)

Question 12

why do we not vaccinate for TB in the U.S.?

Answer 12

• not that effective

- TB skin test will always test positive = ineffective surveillance tool

Question 13

Ways to prevent TB

Answer 13

• improve DOTS implementation
• improve social conditions (poverty, water, nutrition, housing)
• improve public health care systems

Question 14

what are some examples of prion diseases?

Answer 14

• scrapie (sheep)
• kuru (humans)
• mad cow disease
• Creutzfeldt-Jakob disease (CJD) in humans

Question 15

PrP^c

Answer 15

normal, “non-virulent” protein
unknown function
protein found in brain

Question 16

PrP^sc

Answer 16

infectious prion (abnormal, misfolded)

Question 17

why are prions infectious?

Answer 17

normal prion proteins are converted to prion proteins -> neurons die and vacuolar areas form in gray matter (ultimately neurological deteriation)

Question 18

what kind of disease are prion diseases?

Answer 18

transmissible spongiform encephalopathies (TSEs)

Question 19

what are the symptoms of prion disease?

Answer 19

loss of motor coordination, dementia, other neurological symptoms, death (autopsy reveals “sponge-like” brain full of holes)

Question 20

treatment or cure for prion disease

Answer 20

NONE

Question 21

examples of animal TSEs

Answer 21

• mad cow disease (Bovine Spongiform Encephalitis, BSE)
• scrapie
• TSEs in household cats, deer, elk, and mink
• Chronic Wasting Disease (CDW) in mule deer, white-tailed deer

Question 22

what are the three ways Creutzfeldt-Jakob disease (CJD) occurs?

Answer 22

1) sporadic (85% of cases; worldwide but only 1-2 mortality cases per million people)
2) hereditary (gene mutations; 5-15%)
3) iatrogenic (via contaminated surgical equipment, corneal transplants, blood transfusions - rare)

Question 23

what age does CJD affect and what is the prognosis?

Answer 23

age 65; death within 1 year

Question 24

what TSE leads to the cannibalistic eating of brains?

Answer 24

Kuru

Question 25

what prion disease is obtained from ingesting BSE-contaminated beef? Where is this disease commonly found?

Answer 25

vCJD (variant CJD)

found in U.K.

Question 26

what are ways to prevent prion disease?

Answer 26

• ban against animal products in livestock feed
• increased surveillance
• diagnosis (presence of protein in cerebrospinal fluid)