Measles (also called rubeola or morbilli) was once one of the most common childhood infections in North America. In the early 1960s, over half a million children were infected every year. In 1963, the creation of a measles vaccine changed everything. Today, while very few new cases of measles occur each year in developed countries, it still occurs in epidemic proportions in developing regions, infecting around 20 million people and causing around 140,000 deaths worldwide.
Even though a majority of patients recover from infection, measles can have serious complications. Early in infection, the brain tissue can become inflamed (encephalitis). A later complication can occur several years later, causing brain damage.
Measles is one of the most contagious vaccine-preventable infections in humans. The one antigenic type of the measles virus is only found in humans. This means that if high immunization rates are maintained, it may be possible to eradicate this virus, just like smallpox and polio.
Measles is caused by a type of virus called a paramyxovirus. It is a highly contagious virus, usually transmitted in tiny droplets when an infected person coughs, breathes, or sneezes. The measles virus can also survive for approximately 2 hours on infected surfaces like doorknobs and telephones. Research shows that only 10% of unvaccinated people who share a house with a measles patient avoid infection.
Symptoms and Complications
For 1 or 2 weeks after an infection, the virus multiplies without causing any symptoms. This is called the incubation period. After that, symptoms such as cough, fever, runny nose, red eyes, and tearing will appear. Children may also become irritable.
About 2 days after initial symptoms appear, small, red, irregular spots with a whitish or bluish centre called Koplik's spots develop on the inside of the cheeks near the molars. About 2 days after Koplik's spots develop, a rash (large brown or red blotches) develops behind the ears, and perhaps on the forehead and face, and can spread to the trunk, arms, and legs. The rash usually begins to fade within 5 days, often starting at the top (head) before it clears up in the lower parts of the body (legs). Once the rash has completely disappeared, the skin may appear a bit brownish and the top skin layers may peel off soon afterwards.
The rash isn't painful and does not itch. Some people may experience increased sensitivity to light, and their eyes may become red and inflamed. During the peak of the infection, a fever usually develops with a body temperature as high as 40°C (104°F).
Measles is contagious for about 4 days before the rash appears and about 5 days afterwards. It's best for people with measles to stay away from others so they won't get infected.
Measles usually runs a simple course with few complications, but in certain cases, problems can arise. The most common complication is pneumonia, an infection of the lungs, especially in people with weakened immune systems. This is the most common cause of death from measles in young children. A second common infection that occurs as a result of the measles virus is a middle ear infection (otitis media). These infections can possibly cause permanent hearing loss.
In about 1 in 1,000 cases, measles can affect the brain, causing encephalitis. This usually happens during the late stages of infection, 2 to 14 days after the rash develops. Unfortunately, there's no cure, but some people may recover on their own without any further problems. Many people, however, are left with permanent problems such as seizures.
In a small number of patients, the virus can take permanent rest in the brain and be awakened years later to cause re-infection and brain damage. This results in a condition called subacute sclerosing panencephalitis (SSPE), which is often fatal. This condition is very rare, occurring about 7 to 10 years after measles virus infection.
Measles can also cause complications such as hepatitis (inflammation of the liver) or appendicitis (inflammation of the appendix). Very rare complications include heart and kidney problems.
Pregnant women who catch measles have a greater risk of miscarriage.
Making the Diagnosis
It's important to detect measles as soon as possible, since the disease is contagious at an early stage. Your doctor will take a medical history and perform a physical exam to help diagnose measles. Common signs and symptoms such as rash, fever, cough, sneezing, and red eyes are easily noticeable and useful to diagnose measles.
If someone who's never had measles complains of cold or flu-like symptoms, looking inside the person's mouth can tell a lot. There are small, red, irregular spots called Koplik's spots that develop on the inside of the cheeks, near the molars. Each spot will have a whitish or bluish centre. Koplik's spots are a sure sign of measles and appear about two days after initial symptoms, which is about 2 days before the rash develops. Once doctors see these spots in the mouth, they usually don't bother with blood or tissue tests to make the diagnosis, but will order these tests for public health purposes to help control measles outbreaks.
Treatment and Prevention
Like the common cold, measles is a viral infection that the body will fight off and will go away with time. There are no medications that can kill off the virus, so the only useful treatments are those that help relieve symptoms. For example, medications like acetaminophen* or ibuprofen can reduce fever and other symptoms. Cough or sore throat medications may also help.
Doctors may prescribe high doses of vitamin A to children who have measles, especially those at risk. Children at risk include those who are in the hospital because of measles, and those who have a suppressed immune system, have a vitamin A deficiency, or have recently moved from countries where the death rate from measles is high.
Over 95% of children fully vaccinated against modern measles are protected against the disease. As far as we know, it is a lifelong protection. In about 15% of cases, people may get a very mild, non-contagious form of measles about 10 days after vaccination. This is due to the fact that the vaccine contains a live but weakened strain of the virus.
For mothers who've already had measles, their newborn babies are protected for about a year due to the transfer of special antibodies from the mother's immune system. Because of this, the measles vaccine may not work in a child's first year of life. The common practice in children is to vaccinate once at 12 to 15 months of age, and to give a booster shot at 4 to 6 years of age (before they attend school).The measles vaccine is commonly given in the same injection as the mumps and rubella vaccine, in what is commonly known as MMR vaccine.
The vaccine can prevent measles from developing in people who have been exposed to the virus, but it only works if it's given within 72 hours of exposure. Generally, the measles vaccine isn't given to babies less than one year old, pregnant women, or people with severely damaged immune systems. If a pregnant woman or newborn baby is exposed to the measles virus, they will be given a transfusion of immune serum globulin instead. This contains special antibodies that defend the body against the virus.