Virus 5 (RNA): Measles

Question 1

How has the incidence of measles changed over the last century and how have vaccines influenced this?

Answer 1

Still about 145,700 deaths every year. 85% of the world covered with vaccine.

Question 2

What kind of virus is measles?

Answer 2

paramyxovirus that grows in cytoplasm of cells

• Paramyxovirus. Transmitted through air and direct contact: highly infectious at onset of symptoms – from 4 days prior to rash to 4 days post-rash. R0 = 12–18.
• About 5 million cases/year. 100,000 measles deaths/year

Question 3

How is measles transmitted?

Answer 3

From resp tract -> blood -> lymph -> back to skin -> shedded from skin -> symptoms appear

Question 4

How does herd immunity work?

Answer 4

“the reduction of infection or disease in the unimmunised segment as a result of immunising a proportion of the population”

Question 5

Who is at risk from measles?

Answer 5

Severe measles is more likely among malnourished children, especially those with insufficient vitamin A, or whose immune systems have been weakened by HIV/AIDS or other diseases. Women infected while pregnant are also at risk of severe complications (WHO).

Question 6

What are the symptoms of measles?

Answer 6

• Very high fever, cough, red/watery eyes, koplik’s spots inside checks
• Day 4 widespread macular rash starting behind ears/face, spreads and then fades
• Superimposed bacterial infection [pneumonia, diarrhoea, etc.] causes deaths: children malnourished, coinfected, pregnant, young, etc.
• Can also cause acute encephalitis and encephalomyelitis [acute demyelination]

Question 7

What are the adverse effects of measles infection?

Answer 7

• stillbirth
• blindness
• mental retardation
• abortion

Question 8

How do we confirm a clinical diagnosis of measles?

Answer 8

• WHO case definition: fever, rash + 1 of: cough, coryza, conjunctivitis
• Serology often not indicated but can check measles IgM [ELISA]
• PCR for measles of throat/nose swabs/urine samples

Question 9

How do we manage a measles infection?

Answer 9

• Supportive Care
• Vitamin A supplementation x2 doses 24-hours apart for children
• Treat superimposed bacterial infections
• Avoid corneal damage/ulceration with Vitamin A supplementation

Question 10

How do you prevent a measles outbreak?

Answer 10

Question 11

When is the MMR vaccine given?

Answer 11

• For anti-vaxxers:
  
  • THERE IS NO SCIENTIFIC EVIDENCE TO SHOW THAT MMR VACCINE IS HARMFUL
• measles vaccine produces seroconversion in over 90% of recipients if given at the age of 9 months

Question 12

What are the benefits since the push for immunising everyone against measles?

Answer 12

Question 13

Is measles a seasonal disease?

Answer 13

• Measles is a winter disease

Question 14

MCQ tips

Answer 14

• Ophthalmology pictures showing the spectrum of Vitamin A deficiency disease
• In a refugee setting, mass immunisation + vit A is a priority
• Any case of fever + consider measle

Question 15

Preventive medicine sample question: You are a doctor in a refugee camp that has just been established. No health assessments of interventions have taken place yet. You suspect a measles outbreak: how would you implement a treatment and control programme (20)

Answer 15

Question 16

Preventive medicine sample question: What are the top ten priorities in setting up a refugee camp? Provide a brief outline for each priority. (20)

Answer 16