Measles

Measles is one of the leading causes of death in young children globally, despite the availability of a safe and effective vaccine. In 2018 there were more than 140,000 measles deaths globally, mostly among children younger than five years. A measles outbreak occurs when the measles vaccine coverage is low or has dropped below 95 per cent. Vaccination has reduced deaths caused by measles by 73 per cent between 2000 and 2018 globally, but measles remains common in many countries, particularly in parts of Africa and Asia.  That said, measles cases skyrocketed from 2017 to 2019, with outbreaks happening in seven previously measles-free countries. Many countries not previously considered at risk are now experiencing outbreaks. Measles is one of the most contagious infectious diseases and can spread very quickly but can be controlled with mass vaccination campaigns. Measles infection leads to loss of immunity to other deadly diseases, increasing the risk of death from other causes.

The following are standard case definitions to allow national health authorities to interpret data in an international context. However, during an outbreak case definitions may be adapted to the local context and the Red Cross Red Crescent should use those agreed/established by national health authorities. NB: Consider that during community-based surveillance, volunteers should use broad (simplified) case definitions (referred to as community case definitions) to recognize most or all possible cases, provide relevant risk communication and appropriate actions and encourage them to seek care. Other actors such as healthcare workers or investigators studying the cause of a disease, on the other hand, can use more specific case definitions that may require laboratory confirmation.

Suspected case: Any person with fever greater than or equal to 38 °C AND generalized rash (lesions with a flat base called maculopapular, and a number of small fluid-filled blisters) AND ONE of the following: cough, runny nose or red eyes (conjunctivitis) OR any person in whom a clinician suspects measles.

Confirmed case:

• Laboratory confirmed case: symptomatic case with laboratory confirmation.
• Epidemiologically linked case: a suspect case of measles that has not been laboratory confirmed, but was linked by geography and time, with rash starting 7—23 days apart from another laboratory confirmed or epi-linked measles case

WHO case definition source of information: https://www.who.int/immunization/monitoring_surveillance/burden/vpd/WHO_SurveillanceVaccinePreventable_11_Measles_R2.pdf

The specific threshold must be developed based on local epidemiology and immunization programme objectives. The outbreak threshold may, and should, change as the incidence of measles changes. In countries with no recent measles cases reported, a single case should trigger a detailed case investigation.

• Children who are not vaccinated are most at risk. It is estimated that in an unvaccinated population, nearly all children develop measles before adolescence.
• Measles is common particularly in parts of Africa and Asia. More than 95 per cent of measles deaths occur in countries with low per capita incomes and weak health infrastructures.
• Measles outbreaks can be particularly deadly in countries experiencing or recovering from a natural disaster or conflict. Damage to health infrastructure and health services interrupts routine immunization and overcrowding in residential camps greatly increases the risk of infection.
• Overcrowded areas where a person-to-person spread is easily possible.
• Lack of proper sanitation and hygiene measures.

Attack rates will vary from one outbreak to another. In case of an outbreak, consult the latest information provided by health authorities.

Measles is an extremely contagious disease. In a completely unprotected population, one person infected with the measles virus will infect, on average, between 12 and 20 people. The attack rate is 90 per cent or greater among non-immune contacts (i.e. 9 out of 10 susceptible people who are exposed to measles will get sick). In areas where part of the population has been vaccinated or infected by the virus previously, the reproductive ratio is lower.

• Unvaccinated young children under five years old.
• Unvaccinated adults over 30.
• Unvaccinated pregnant women are at highest risk of severe measles disease and its complications. The pregnancy may end in miscarriage or preterm delivery.
• People with weakened immune systems, such as those receiving chemotherapy, transplant recipients, or people living with HIV/AIDS or other diseases.
• People with chronic diseases such as renal disease, cancer, chronic lung or liver disease and diabetes.
• People suffering from malnutrition and vitamin A deficiency.

Measles morbillivirus (also called measles virus).

Humans.

Airborne and droplet spread:

• Viral droplets of saliva/mucus from one person to another, mainly by coughing or sneezing.
• Sharing eating and drinking utensils can increase droplet spread.
• The virus remains active and contagious in the air or on infected surfaces for up to four hours.

Contact transmission:

• Close personal contact or direct contact with infected nasal or throat secretions.

10 to 14 days (range 7—23 days).

Infected people can spread measles to others from four days before up to four days after their rash appears. It can be longer in malnourished or immunosuppressed individuals.

• Measles generally starts with a high fever, runny nose, cough, red and watery eyes, and sometimes white spots inside the cheeks.
• Red blotchy rash appears after several days, usually on the face and upper neck, and over about three days spreads to the rest of the body.
• In severe cases, serious complications include blindness, brain swelling, severe diarrhoea and related dehydration, ear infections or severe respiratory infections like pneumonia.
• In populations with high levels of malnutrition and a lack of adequate health care, up to 10 per cent of measles cases result in death.

Other diseases with rash and fever, e.g. hand, foot and mouth disease (HFMD), Parvovirus B19 infection, rubella, dengue fever, chickenpox, monkeypox, mumps.

• Detection of measles-specific IgM antibody and measles RNA by real-time Polymerase Chain Reaction (RT-PCR) are the most common methods for confirmation of measles infection.
• Efforts should be made to obtain a serum sample and throat swab (or nasopharyngeal swab) from suspected cases at first contact.

Please refer to the appropriate local or international guidelines for clinical management. All clinical management including the administration of any treatment or vaccine should be conducted by health professionals.

• No specific antiviral treatment exists for the measles virus.
• Severe complications from measles can be avoided through supportive care that ensures good nutrition, adequate fluid intake and treatment of dehydration with WHO recommended Oral Rehydration Solutions (ORS). This solution replaces fluids and other essential elements that are lost through diarrhoea or vomiting.
• All children in low-income countries diagnosed with measles should receive two doses of vitamin A supplements, given 24 hours apart. It can help prevent eye damage and blindness. Vitamin A supplements have also been shown to reduce the number of measles deaths.
• This is a vaccine-preventable disease and measles vaccination is part of routine immunization programmes (two doses). Please refer to the national immunization schedule. The measles vaccine is often incorporated with rubella and/or mumps vaccines. It is equally safe and effective in the single or combined form.

• Natural immunity after infection is lifelong.
• Vaccine efficacy is 93 per cent at 12 months of age and 98 per cent at 15 months of age. This increases to more than 99 per cent after two doses of the vaccine is received.
• Vaccine provides lifelong immunity.