KISS: Measles

BMJ 2017 BJGP 2018 BJGP 2023

NHSE risk assessment/prevention Jan 2024 UKHSA Guideline Jan 2024

Background:

• Measles is a highly infectious virus transmitted via respiratory droplet with an R0 number of 15-20 (i.e. 1 index case will infect 15-20 non-immunised people); it is thought that being in the same room as an infected individual for 15mins or more confers a transmission risk of >90%; transmission mostly by droplet spread or direct contact.
• While mortality is rare in the UK complications such as pneumonitis, secondary bacterial infections and tracheobronchitis (‘measles croup’) are common leading to high rates of hospital admission.
• Rarer serious complications include encephalitis (0.05%-0.1%) & subacute sclerosis pan encephalitis (SSPE ~0.01%). SSPE presents a few years after infection with progressive neuro-cognitive symptoms, often leading to coma and death.
• Vaccination remains pivotal - the vast majority of infected children have not been vaccinated. Vaccination with 2 doses provides excellent immunity which is thought to be lifelong.
  • To achieve control countries need to reach vaccination rates of ~95%. Currently in the UK (BMJ 2024;384:q113) coverage of 2 MMR vaccines by 5 years of age is <85%, the lowest level since 2010/11, with large regional variation.

Assessment/Diagnosis:

• Incubation period: typically 7-10 days (can be 7-21 days); infectious 4 days before and after the rash appears, with peak infectivity in the first 3 days prior to the rash developing.
• Prodrome - Initially fever (often >390C & usually peaks at the onset of rash), cough, coryza, conjunctivitis.
• Rash follows 2-4 days later - erythematous maculopapular rash, blanching; starts on the face, often behind ears, then spreads down the body to trunk and can be generalised - click here for images. generally not itchy and lasts 3-7d.
• Koplik’s spots - white spots 2-3mm on the oral mucosa; can be confused with other oral lesions so can be unreliable as a marker for disease.
• Differential diagnoses (click here Annexe 1) include roseola, parvo B19 and scarlet fever;
• Oral fluid is used for measles surveillance. It is more acceptable and easier than blood tests, and can still be tested for IgM, IgG and measles RNA. Therefore it can: 1) reliably confirm or exclude measles, 2) shows if this is a primary or re-infection, and 3) genotype confirmed cases. Testing kits will be sent out direct from health protection teams (HPTs).

Management: (click here for a summary ‘Think Measles’ pathway/poster)

• Risk assess, ideally remotely initially.
• Although the combination of rash, fever (peaking at onset of rash), coryza and conjunctivitis is almost unique to measles, clinical features can be unreliable, epidemiological factors may help prediction better (vaccination history; travel from area of outbreak/high endemic levels; cultural/religious groups with low vaccine uptake; contact with case).
• If F2F assessment needed isolate in a side room and minimise waiting time; PPE recommended for clinician (gloves, apron, mask and eye protection) and ideally a surgical mask for the patient.
• If transfer is required warn the hospital/ambulance if measles is suspected.
• Measles is a notifiable disease. Refer any suspected cases to the local HPT. Click here to find your local HPT.
• If a vulnerable person (aged <1 year, pregnant, immunocompromised) contact HPT immediately by phone.
• For most patients, management is the same as for any viral infection: rest, fluids, paracetamol PRN with safety netting for complications or deterioration.
• Children <2 years old are potentially high risk - discuss management with the on-call paediatric team.
• Patients should avoid contact with pregnant women, children (in particular babies who will not have been vaccinated yet) and unvaccinated people.
• Children can return to school/childcare settings 4 days after the onset of rash.
• Non-immunised contacts need to be excluded from school/childcare settings for the incubation period (up to 21 days).
• Public health may offer post-exposure prophylaxis with human normal immunoglobulin to non-immune contacts at higher risk (this includes children <1yo).
• Patient information - click here