Exam 4 - Measles

Question 1

measles was initially more dreaded than __________

Answer 1

smallpox

Question 2

measles caused by

Answer 2

infectious agent in blood

Question 3

measles virus (MV) also called

Answer 3

rubeola, 10-day measles, red measles

Question 4

measles clinical features

Answer 4

• 7-14 day incubation period
• prodromal period (2-4 days) - high fever, barky cough, runny nose, conjunctivitis, Koplik spots
• flat red blotchy rash (face to body)

Question 5

Measles complications

Answer 5

common - ear infections, diarrhea
children - respiratory or neurological complications (pneumonia, encephalitis)

Question 6

Subacute Sclerosing Panencephalitis (SSPE)

Answer 6

• develops 7-10 years after infection
• deterioration of the CNS progressing to vegetative state and death
• higher risk with initial infection before 2 years old

Question 7

measles transmission

Answer 7

• person to person by large respiratory droplets
• airborne for 2 hours
• direct contact with secretions
• highly contagious - 4 days before rash to 4 days after rash starts

Question 8

measles cellular pathogenesis

Answer 8

• infects alveolar macrophages & dendritic cells
• spreads to regional lymph nodes
• systemic infection
• second virimmia - 5-7 days after initial infection
• virus transmitted to epithelial cells –> rash
• virus released into respiratory tract –> contagious

Question 9

encephalitis is caused by

Answer 9

virus crossing blood-brain barrier

Question 10

measles immune amnesia

Answer 10

• immune suppression during acute infection
• infects memory B and T cells - destroyed by immune system
• new immune memory cells are MeV specific
• increased vulnerability to all other pathogens
• 2-3 years for immune system to be restored

Question 11

measles family and genus

Answer 11

paramyxoviridae family, morbillivirus genus

Question 12

measles structure

Answer 12

• pleiomorphic
• enveloped, helical capsid
• -ssRNA genome (24 genotypes, 1 serotype)

Question 13

measles is rapidly inactivated by

Answer 13

heat, sunlight, acidic pH, ether, trypsin

Question 14

measles virion and genome proteins

Answer 14

N protein - helical capsid, binds 6 ntds
F protein - fusion (on envelope)
H protein - hemagglutinin (on envelope)
P, V, C proteins - immune evasion

Question 15

measles replication

Answer 15

1. Binding to SLAMF1/CD150 and Nectin-4 receptors at cell surface
2. Fusion at memb - H (binds to receptor) and F protein (triggers fusion
3. Transcription - L and P RNAP
4. Translation
5. Genome replication - N and P
6. Genome associates w/ N, P, and L
7. Assembly - M protein
8. Budding - M protein

Question 16

Laboratory diagnosis of measles

Answer 16

• RT-PCR of throat swabs, nasopharyngeal aspirates, or urine
• Igm in serum sample

Question 17

measles treatment

Answer 17

Symptomatic - rest, fluids
- medication for aches, pains, fever
- nutrition, vitA supplementation
- no antivirals

Question 18

measles vaccines

Answer 18

• live, attenuated
• combination vaccine
• 2 doses
• revaccination recommended under certain circumstances

Question 19

measles epidemiology

Answer 19

• no animal reservoir
• eradicated from US in 2000
• occasional outbreaks

Question 20

why are there measles outbreaks

Answer 20

• declining vaccination rate
• local variation in vaccination rate
• global measles activity increasing

Question 21

current measles outbreak

Answer 21

• 11 outbreaks
• 11% hospitalization
• 3 deaths - young, healthy children