20. a. Measles

Question 1

Which characteristic best describes an infection, such as measles, that can be eradicated globally?

Answer 1

The reservoir is confined to humans

Question 2

How frequent is encephalitis following measles

Answer 2

1/1000

Question 3

What is the best description of Koplik spots?

Answer 3

Red spots with whitish/bluey centres on the buccal mucosa

Question 4

What should be administered to contacts of patients with acute measles, who themselves are susceptible, to reduce the likelihood of acquiring measles?

Answer 4

Human immunoglobulin

Question 5

Is measles a DNA or RNA virus?

Answer 5

RNA

Question 6

What is the genus of the measles virus?

Answer 6

Morbillivirus

Question 7

What isolation precautions are taken for measles?

Answer 7

Airborne

Question 8

What is the incubation period for measles?

Answer 8

10-12 days

Question 9

When is measles infectious?

Answer 9

From 4 days before until 4 days after the rash appears

Question 10

Why is measles so infectious?

Answer 10

Low infecting dose

Many virus particles are shed at once

Question 11

What are the virulence factors of measles?

Answer 11

Haemaglutinin allows adhesion

Fusion protein allows fusion of the virus and the host cell membrane

Question 12

How does measles get into the body?

Answer 12

Large or small droplets inhaled or deposited on eyes, nose, mouth

Question 13

What cells does the measles virus bind to?

Answer 13

Dendritic cells in alveolar spaces and submucosa of the respiratory tract

Question 14

Where does the measles virus migrate to after binding to DCs?

Answer 14

BALT and draining lymph node where it causes massive replication of B and T cells

Question 15

What happens 2-3 days after replication in the respiratory tract and regional lymph nodes?

Answer 15

Primary viraemia

Infection of the reticuloendothelial system

Question 16

What cells are involved in the reticuloendothelial system?

Answer 16

Monocytes
Macrophages
Lymphoid organs
Bone
Liver
Lungs

Question 17

What happens during the secondary viraemia?

Answer 17

5-7 days after the initial infection

Infection of the respiratory tract and other organs

Question 18

What are the signs of acute measles?

Answer 18

Fever
Cough, runny nose, conjunctivitis
Koplik's spots and maculopapular rash
Anorexia
Generalised lymphadenopathy
Diarrhoea

Question 19

Describe the maculopapular rash associated with measles

Answer 19

Initially maculopapular but can join up
Begins at hairline towards feet and disappears in the same order
Initially blanch but don’t by day 3-4

Question 20

What is the brown staining on the skin after the measles rash caused by?

Answer 20

Capillary leakage

Question 21

How long does the measles rash last for?

Answer 21

5-6 days

Question 22

Which groups of people are more likely to have complications of the measles?

Answer 22

Very young
Adults
Immunocompromised

Question 23

What are the most common causes of death from measles?

Answer 23

Pneumonia
Diarrhoea
Encephalitis

Question 24

What are other causes of morbidity?

Answer 24

Otitis media
Respiratory infection
Convulsions
SSPE
Reactivation of HSV

Question 25

How can measles cause blindness?

Answer 25

Retinitis

Corneal ulceration in vitamin A deficiency

Question 26

What are the neuro complications associated with measles?

Answer 26

Measles inclusion body encephalitis
Acute disseminated encephalomyelitis
Subacute sclerosing panencephalitis

Question 27

How long after the onset of the rash does each neuro complication occur?

Answer 27

MIBE: few days
ADEM: 1-2 weeks
SSPE: 7 years

Question 28

How is SSPE diagnosed?

Answer 28

IgM to measles in CSF

Question 29

What lab tests can be done for measles?

Answer 29

IgM on blood and oral fluid

PCR on oral fluid to detect virus

Question 30

How can measles be prevented?

Answer 30

Live vaccine given at 1 year and age 4/5

PEP within 72 hours