Measles, Mumps and Rubella, an update

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• Measles, Mumps and Rubella, an update

Carol Kerr Consultant Health Protection
Nurse Cheshire Merseyside Health Protection Unit
September 2008
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Measles Epidemiology

• Prior to use of measles vaccine
• Large epidemics every 2nd year with up to 800,000
  cases
• Mostly pre-school children
• Almost all adults immune to disease
• In 1988 change to MMR
• Coverage 93 - measles now rare
• Unvaccinated children not exposed to natural
  infection
• Increase in older children and adults
• Often associated with travel and migration

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Diseases not prevalent in UK so do we need to
vaccinate?

• Measles, mumps and rubella now rare due to
  success of immunisation programmes
• Still killers and causes of disability in
  developing countries
• Must avoid complacency - recent measles outbreak
  in Ireland and clusters in UK

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Measles Disease

• Highly contagious each case will infect 17
  people in non immune population
• Paramyxovirus
• Respiratory transmission 4 days before to 4 days
  after rash onset
• High complication rate in malnourished and
  immunosuppressed children

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Measles notifications vaccine coverageEngland
and Wales 1950-2000
Insert Image
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Measles Clinical Features

• Incubation period 10-12 days
• Prodrome
• Fever
• Cough, coryza, conjunctivitis
• Koplik spots

• Rash
• 2-4 days after prodrome, 14 days after exposure
• Maculopapular, becomes confluent
• Begins on face and head
• Persists 5-6 days

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Measles Clinical Features
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Measles Complications

• Diarrhoea 8
• Otitis media and pneumonia 5 10
• Encephalitis 1 in 10,000
• Hospitalisation 1 in 5
• Death 2 in 10,000

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Measles Complications by Age Group
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Mumps Disease

• Moderately contagious viral illness with
  respiratory transmission
• Paramyxovirus
• Transmission 7 days before to 5 - 9 days after
  parotitis onset
• Frequent cause of institutional outbreaks in
  prevaccine era

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Mumps Clinical Features

• Incubation 14 18 days
• Unspecific prodrome
• Parotitis 30 40
• Up to 20 asymptomatic
• May present as lower respiratory illness,
  particularly in preschool children

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Parotitis
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Mumps Complications

• Meningitis 20 usually benign
• Orchitis 20 in postpubertal males
• Pancreatitis 2 5
• Deafness 1 in 20,000
• Death very rare

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Mumps in a Healthcare Setting

• Nosocomial transmission rare
• No evidence complication rate higher in
  immunosuppressed
• Isolate patient or exclude staff for 9 days after
  onset of symptoms
• Respiratory precautions (gown and gloves)
• Do not exclude staff contacts from work
• Re-deploy non immune contacts with symptoms if
  working in high risk setting (from day 12 to 25
  after exposure)

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Mumps - Cheshire Merseyside 2005
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Mumps Laboratory Diagnosis

• Isolation of mumps virus
• Serology
• positive IgM antibody or significant increase in
  IgG
• Saliva positive IgM

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Mumps in Pregnancy

• Reassure
• Evidence for increased risk of foetal loss in 1st
  trimester weak
• No evidence increased risk severe congenital
  abnormality
• Do not exclude pregnant women from setting such
  as work during mumps outbreak

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Mumps and Measles Control and Prevention

• MMR
• Routine childhood immunization age 12-15 months
  and preschool
• Catch up campaign for students and school leavers
  
• Check vaccination status at school entry
• Check immunity of health care workers and
  international travelers history of disease or 2
  MMR
• Breastfeeding
• Reduce poverty

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Response to a Case

• On call action usually none
• Notify to Health Protection Agency
• Exclude from school or work for 5 days from
  symptom onset
• Check vaccination status
• Laboratory confirmation usually saliva test
• Post-exposure vaccination will not prevent
  infection

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Epidemiology of rubella

• Last outbreak occurred in 1996
• Most cases young adult males
• Not vaccinated routinely with MMR
• Too old for MR campaign in 1994
• Rubella infection now exceedingly rare in UK
• Congenital rubella syndrome now rare
• Small increase in CRS associated with 1996
  outbreak
• Small number of antenatal women are still at risk
• Protection from exposure

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Risk of intrauterine transmission during
different stages of pregnancy
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Rubella clinical feature
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Rubella (German Measles)

• For most people rubella is a mild infectious
  disease, although it can have serious
  consequences for pregnant women. It was
  previously common among children aged four to
  nine years.
• It is transmitted by direct contact or droplet
  spread. Humans are the only known hosts.

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Clinical presentation

• It causes a transient red rash, swollen lymph
  glands around the ears (post-auricular) and back
  of head (sub-occipital), and occasionally in
  adults, arthritis (any abnormality of a joint
  caused by inflammation) and arthralgia (pain in a
  joint caused by inflammation).
• The rash may be fleeting and may look like the
  rash caused by other viruses, therefore, clinical
  diagnosis by rash is unreliable
• The incubation period is 14 - 21 days

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Rubella

• Clinical diagnosis is unreliable as the rash may
  be fleeting and is not specific to rubella.
• Rubella is spread by droplet transmission.
• The incubation period is 14 to 21days, with the
  majority of individuals developing a rash 14 to
  17 days after exposure.
• Individuals with rubella are infectious from one
  week before symptoms

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Can MMR cause autism?

• Wakefield et al 1998 Lancet - suggested link
  between MMR and new syndrome
• Parental testimonies of regressive autism after
  MMR
• Wakefield et al 1999 Lancet - suggested rise in
  autism in UK California coincided with
  introduction of MMR

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Can MMR cause autism?

• Wakefields 1998 work rejected by scientific
  community - flawed methodology, only 12 subjects,
  biologically implausible
• Taylor et al 1999 Lancet - N.Thames study of 498
  cases autism
• no clustering of onsets shortly after MMR
• no age difference at diagnosis for vaccinated or
  unvaccinated at 18 months

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Vaccine safety testing

• Trials carried out in 3 phases
• I - small number healthy adult volunteers
• II - sample 100-200 of intended recipients
• III - protection against disease evaluated by
  comparing vaccinated and unvaccinated
• Prior to general use, each batch has extensive
  quality control and safety testing
• Extensive post-marketing surveillance

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Vaccine licensing

• Tens of millions of doses MMR given before
  introduction in UK and shown to be safe and
  highly effective
• Ongoing surveillance for adverse events via
  case-note tagging and yellow card system

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Why two doses of MMR?If uptake is 88, 12
unvaccinated and without a second dose

• 10 dont respond to measles component
• So 21 of children susceptible to measles in one
  school year
• Enough to risk large outbreak every 4-5 years
• Herd immunity needs to be 95 (i.e. only 5
  susceptible) to eliminate spread

• 13 dont respond to mumps component
• So 25 susceptible to mumps in one school year
• Potential for continuing outbreaks, especially in
  school age children (42 of confirmed cases in
  10-14 yr olds had received a single dose)

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Why a second dose (contd)

• 90 of children who failed to respond to single
  dose of MMR, respond to second dose
• So
• second dose produces a response in most children
  who failed to respond to first dose, thus
  reducing number of those susceptible
• is an opportunity to immunise those who have not
  had any doses
• acts as booster for those who were protected
  first time around

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Summary

• Control of measles and rubella good
• Increase in measles in 2002in line with
  predictions
• size of outbreaks similar to those previously
  described
• national increase in notifications (? due to
  increased awareness)
• Increase in mumps since 1998 in older school age
  children e.g. Bootle outbreak
• MMR coverage has dropped (83 nationally, below
  80 in Sefton)
• 2 doses necessary to prevent resurgences and give
  long term protection to individual children

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and finally

• Thank you.
• Any questions?
• www.hpa.org.uk Carol.kerr_at_hpa.org.uk 0151
  290 8360