Contents
Introduction
Measles is a previously common (incidence now greatly reduced due to vaccination) usually childhood infection. Most cases are self-limiting, it is extremely infectious and carries a complication rate of 10-20%. Measles remains a major cause of childhood mortality worldwide with an estimated 100 000 deaths annually. Measles is the leading cause of vaccine preventable death worldwide.
In recent years, cases in the developed world have risen due to the anti-vaccine movement, initially sparked by fears over the MMR vaccine in the early 2000s.
- Measles is now relatively rare in the UK since the advent of vaccination
- Older children have more severe disease
- Caused by the Morbillivirus, which is a type of paramyoxovirus
- This is a single stranded, enveloped RNA virus
- It is a highly contagious infection of the respiratory system, and can be passed on by airborne transmission, via droplets expelled in coughing, sneezing and respiration.
- Maternal antibodies tend to provide immunity in the first 6 months of life
- In the developing world, the death rate is around 5-10%
- In developed countries is this <0.1%
Disease progression and symptoms
- Incubation period is typically 10-14 days, followed by the symptomatic phase, of typically 7-10 days.
- Patient is infective for the last 2 days of incubation (i.e. before symptoms are apparent), and for the first 6 days of the symptomatic phase.
- Fever – temperature increases from day 1-5, peaks at day 5, before falling.
- Koplik’s spots –these are small white spots on the buccal mucosa. Visible usually from days 2-5. These are diagnostic for measles, but often not seen, and when present are transient.
- Cough – usually apparent through the whole symptomatic phase
- Conjunctivitis and Coryzal Symptoms – days 1-5.
- Rash – this usually starts off behind the ears, and spreads down the body. Initially a maculopapular rash, it typically expands and becomes indistinct. Usually lasts from about days 3-7, but there is a possibility of desquamation towards the end.
- When to exclude from school?
- Until at least 5 days after the onset of the rash. Typically, viral shedding stops around day 6, and the rash starts at day 3. This allows 2 days leeway, excluding the child from school until at least day 8.
Complications
Complications are highest in those aged <1 year, and lowest in those aged 1 to 9 years.
- Otitis media – middle ear infection – occurs in up to 9% of cases
- Pneumonia – occurs in up to 6% of cases and accounts for the majority of death (up to 85% of the deaths) due to measles. The pneumonia in measles is usually a secondary infection with Staphylococcus Aureus or viral secondary infection with adenovirus or herpes simplex virus
- Encephalitis – occurs in 1 in 5000 cases. Presents around 8 days after the onset of symptoms of measles, with lethargy, headache and irritability. Can result in LOC and coma. 15% mortality rate. In up to 40% of cases there will be long-term problems, including; deafness, hemiplegia and learning difficulties.
- Diarrhoea – usually caused by a secondary infection with bacterial or protozoal infections
- Subacute sclerosing panencephalitis (SSPE) extremely rare–Presents approx 7 years after measles infection. Will cause progressive dementia (over several years) and eventual death. Occurs in 1 in 100 000 cases of measles. Caused by a measles virus variant gaining access to the CNS. Diagnosis is confirmed by high levels of measles antibody in the blood and CNS. May also cause CNS abnormalities.
- Vitamin A complications – those with pre-exisiting vitamin A deficiency are more at risk of the complications of meals and severe visual impairment from measles. The WHO recommends that all children in in a country with a measles fatality rate of >1% should be treated with vitamin A supplementation
Measles in pregnancy often causes a more severe illness and is associated with pneumonitis, increased risk of miscarriage, premature birth and low birth weight.
Treatment
Essentially supportive
- Ensure isolation in hospital – to prevent the child coming into contact with immunocompromised patients!
- Ensure adequate nutrition – continue breastfeeding, even with diarrhoea, supplement and intubate if necessary.
- Vitamin A – involved in the immune response, and may be deficient in some, but rarely in the developed world. Supplements available if you suspect it may be a contributing factor
- Ribavirin – antiviral. Should not be used in normal cases, but should be used in immunocompromised patients.
Vaccination in the UK
- Began in UK in 1960’s
- 800,000 cases/year before vaccination programme
- Almost 100% of children used to get it at some point!
- 3,000 cases of measles in the UK in 1990’s
- Number of cases has risen slightly after fall in MMR uptake in late 1990’s
- No link between MMR and autism
- Live attenuated vaccine used – highly effective, and provides life-long protection. The percentage needed to vaccinate for herd immunity is >80%.
- In 10-20% of cases, immunity is not achieved after this first dose, hence the ‘booster’ given to children just before they begin attending school (Age 3 years 4 months)
- Side effects can include mild variants of the symptoms of the disease being vaccinated against. For example, they can include; rash, fever, and loss of appetite (measles). swollen lymph nodes (mumps), and rarely stiff, swollen joints (rubella).
References
- Murtagh’s General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt
- Oxford Handbook of General Practice. 3rd Ed. (2010) Simon, C., Everitt, H., van Drop, F.
- Beers, MH., Porter RS., Jones, TV., Kaplan JL., Berkwits, M. The Merck Manual of Diagnosis and Therapy
- Measles – patient.info
- Measles – RCH
