Measles

Key facts

• Measles is a leading cause of death among young children even though a safe and cost-effective vaccine is available to prevent the disease.
• In 2007, there were 197 000 measles deaths globally - nearly 540 deaths every day or 22 deaths every hour.
• More than 95% of measles deaths occur in low-income countries with weak health infrastructure.
• Measles vaccination efforts have reaped major public health gains, resulting in a 74% drop in measles deaths between 2000 and 2007 worldwide - a drop of about 90% in the eastern Mediterranean and Africa regions.
• In 2007, about 82% of the world's children received one dose of measles vaccine by their first birthday through routine health services, up from 72% in 2000. (Two doses of the vaccine are recommended to ensure immunity, as about 15% of vaccinated children fail to develop immunity from the first dose.)

Measles is a highly contagious, serious disease caused by a virus.

It remains a leading cause of death among young children globally, despite the availability of a safe and effective vaccine. An estimated 197 000 people died from measles in 2007, mostly children under the age of five.

Measles is caused by a virus in the paramyxovirus family. The measles virus normally grows in the cells that line the back of the throat and the lungs. It is a human disease not known to occur in animals.

Targeted vaccination campaigns have had a major impact on reducing measles deaths. From 2000 to 2007 about 576 million children who live in high risk countries were vaccinated against the disease. Global measles deaths decreased by 74% during the period. The largest health gains occurred in the eastern Mediterranean and Africa where measles cases and deaths fell by 90% and 89%, respectively.

Signs

The first sign of measles is usually a high fever, which begins about 10 to 12 days after exposure to the virus, and lasts four to seven days. A runny nose, a cough, red and watery eyes, and small white spots inside the cheeks can develop in the initial stage. After several days, a rash erupts, usually on the face and upper neck. Over about three days, the rash spreads, eventually reaching the hands and feet. The rash lasts for five to six days, then fades. The rash occurs, on average, 14 days after exposure to the virus (within a range of seven to 18 days).

Measles is often a moderately severe illness. Severe measles is more likely among poorly nourished young children, especially those with insufficient vitamin A, or whose immune systems have been weakened by HIV/AIDS or other diseases.

Complications associated with measles cause most deaths. Complications are more common in children under the age of five or adults over the age of 20. The most serious complications include blindness, encephalitis (an infection that causes brain swelling), severe diarrhoea and related dehydration, ear infections, or severe respiratory infections such as pneumonia. As high as 10% of measles cases result in death among populations with high levels of malnutrition and a lack of adequate health care.

People who recover from measles are immune for the rest of their lives.

Who is at risk

Unvaccinated young children are at highest risk of measles and its complications, including death. Any non-immune person (who has not been vaccinated or previously recovered from the disease) can become infected.

Measles is still common in many developing countries - particularly in parts of Africa, the eastern Mediterranean and Asia. More than 20 million people are affected by measles each year. The overwhelming majority (more than 95%) of measles deaths occur in countries with low per capita incomes and weak health infrastructure.

Measles outbreaks can be particularly deadly in countries experiencing or recovering from a natural disaster or conflict. Damage to health infrastructure and services interrupts routine immunization, and overcrowding in residential camps greatly increases the risk of infection.

Transmission

The highly contagious virus is spread by coughing and sneezing, close personal contact or direct contact with infected nasal or throat secretions.

The virus remains active and contagious in the air or on infected surfaces for up to two hours. It can be transmitted by an infected individual from four days prior to the onset of the rash to four days after the rash erupts.

Measles outbreaks can result in epidemics that cause many deaths, especially among young, malnourished children.

In countries where measles has been largely eliminated, cases imported from other countries remain an important source of infection.

Treatment

Severe complications from measles can be avoided though supportive care that ensures good nutrition, adequate fluid intake and treatment of dehydration with WHO-recommended oral rehydration solution (to replace fluids and other essential elements lost from diarrhoea or vomiting). Antibiotics should be prescribed to treat eye and ear infections, and pneumonia.

All children in developing countries diagnosed with measles should receive two doses of vitamin A supplements, given 24 hours apart. This can help prevent eye damage and blindness. Vitamin A supplements have been shown to reduce the number of deaths from measles by 50%.

Prevention

Routine measles vaccination for children, combined with mass immunization campaigns in countries with high case and death rates, are key public health strategies to reduce global measles deaths. The measles vaccine (in use for 40 years) is safe, effective and inexpensive. It costs less than one US dollar to immunize a child against measles.

The measles vaccine is often incorporated with rubella and/or mumps vaccines in countries where these illnesses are problems. It is equally effective in the single or combined form.

In 2007, about 82% of the world's children received one dose of measles vaccine by their first birthday through routine health services, up from 72% in 2000. (Two doses of the vaccine are recommended to ensure immunity, as about 15% of vaccinated children fail to develop immunity from the first dose.)

Global health response

WHO and UNICEF are collaborating to reduce global measles death by 90% by 2010. The strategy includes:

• Strong routine immunization: for children by their first birthday.
• A 'second opportunity' for measles immunization through mass vaccination campaigns, to ensure that all children receive at least one dose.
• Effective surveillance in all countries to quickly recognize and respond to measles outbreaks.
• Better treatment of measles cases, to include vitamin A supplements, antibiotics if needed, and supportive care that prevents complications.

The Measles Initiative - a collaborative effort of WHO, UNICEF, the American Red Cross, the United States Centers for Disease Control and Prevention, and the United Nations Foundation - and other public and private partners play key roles in advancing the global measles strategy.