W14 Epidemiology of Measles (MAH)

Question 1

What is epidemiology? (the bmj)

Answer 1

Epidemiology is the study of how often diseases
occur in different groups of people and why.
Epidemiological information is used to plan and
evaluate strategies to prevent illness and as a guide
to the management of patients in whom disease
has already developed.

Epidemiology of a disease is an integral part of its
basic description. The subject has its special
techniques of data collection and interpretation,
and its necessary jargon for technical terms.

Question 2

Pathophysiology including Transmission:
1. How is measles transmitted?

Answer 2

Measles is a highly contagious viral infection caused by the measles virus (MeV; morbillivirus of paramyxovirus family). It is primarily transmitted through respiratory
droplets. The virus can remain infectious in the air or on surfaces for up to two hours.

Question 3

Pathophysiology including Transmission
2. Invasion and replication
How long is the incubation period?

Answer 3

After exposure, the virus enters the body through the respiratory tract and infects immune cells called dendritic cells and macrophages in the respiratory mucosa. The virus then spreads to local lymph nodes and replicates. Incubation period around 10 days

Question 4

Pathophysiology including Transmission
3. Secondary viremia:

Answer 4

MeV infects lymphocytes, particularly T cells. It travels to regional lymph nodes and enters the bloodstream, leading to a secondary viremia. During this phase, the virus disseminates to various organs and tissues throughout the body, including the respiratory system,
skin, lymphatic system, and CNS.

Question 5

Pathophysiology including Transmission
4. Immune response

Answer 5

Measles stimulates an immune response characterised by the production of antibodies, activation of T lymphocytes, and release of pro-inflammatory cytokines. This immune
response plays a critical role in controlling the infection and clearing the virus.

Question 6

Transmission & Treatment
Clinical manifestations?

Answer 6

Measles manifests in several stages
- initial prodromal stage = fever, cough, runny nose, and conjunctivitis
Infectious from beginning of prodromal phase until 4 days after rash appears
- Koplik’s spots, small white spots with a blue-white centre, on the buccal mucosa
- characteristic maculopapular rash develops (head and spreading to the rest of the
body).

Question 7

6. Immunopathology:
7. Resolution and immunity

Answer 7

Measles can cause immunosuppression …. can make individuals more susceptible to secondary bacterial or viral infections. Leading to complications (1
in 15 cases) – otitis media, bronchitis, pneumonia, convulsions, encephalitis (1 in 5,000 cases), SSPE (subacute sclerosing panencephalitis).

Most individuals recover from measles within two to three weeks and develop lifelong immunity.

Question 8

Prevention: Immunisation against measles

Answer 8

Measles can be prevented by a highly effective and safe vaccine
* Measles-Mumps-Rubella (MMR) immunisation with a first dose at around 13 months and a second
dose (booster) around three and a half years
* Young adults and teenagers who have missed out on MMR vaccination as children are also
encouraged to get immunised
* A complete course of the two doses will protect over 95% of children against measles, mumps and rubella.
* The uptake of MMR (and other childhood) vaccination in Wales is recorded in the COVER
(Coverage of Vaccination Evaluation Rapidly) report. This is published on both a quarterly
and annual basis

Question 9

What is the Personal child health record (PCHR)

Answer 9

• The Personal Child Health Record, also known as the
  PCHR or ‘red book’, is a national standard health and
  development record given to parents/carers at a child’s birth.
• The PCHR is constantly under review. The content and format are overseen by a multi-disciplinary group, hosted by the RCPCH
• Taken to all medical appointments

Question 10

What are the factors Contributing to (?Poor) Immunisation rates in Wales (3)

Answer 10

• Socioeconomic factors and healthcare access
• Vaccine hesitancy and misinformation
• Communication gaps between healthcare providers and the public

Question 11

Cover Report: Coverage of Vaccination Evaluation Rapidly
What do they carry out?

Answer 11

Surveillance of uptake and equality of routine childhood vaccinations in Wales is carried
out by Public Health Wales Vaccine Preventable Disease Programme through the national
COVER scheme in Wales (Coverage of Vaccination Evaluation Rapidly

Question 12

What caused the Measles outbreaks in 2009 and 2012/13 in Wales?

Answer 12

• Low historic levels of MMR vaccination uptake in the area
• Temporally associated with media reports of MMR side-effect

Question 13

What are the Strategies to Improve Immunisation Rates and Prevent Measles Outbreaks?

Answer 13

A. Strengthening vaccination programs and access
B. Enhancing public awareness and vaccine education
C. Collaboration between healthcare professionals and community organisations

1. Achieve and sustain ≥ 95% coverage with two doses of MMR vaccine in the routine
   childhood programme (<5 years old)
2. Achieve ≥ 95% coverage with two doses of MMR vaccine in older age cohorts through
   opportunistic and targeted catch-up (>5 years old)
3. Strengthen measles and rubella surveillance through rigorous case investigation and testing
   ≥80% of all suspected cases with an Oral Fluid Test (OFT)
4. Ensure easy access to high-quality, evidence-based information for health professionals and
   the public

• Interventions: Welsh Health Circulars and
  Welsh Government letters