Measles: Symptoms, Complications, Treatment, and Prevention
Measles is a viral infection that spreads through the air and is among the most contagious infectious diseases. It usually begins with symptoms that can look like an ordinary respiratory infection, but the illness can become much more serious, particularly in young children and people who are not immune.
The infection is caused by the measles virus, which first affects the respiratory tract before spreading throughout the body. A person can transmit the virus several days before the characteristic rash appears, which makes measles particularly difficult to contain once it begins circulating in a community.
Although measles is often associated with childhood, adults can also become infected if they are not immune. The risk of complications is higher in children under 5 and adults over 20, as well as in people with weakened immune systems and children who are malnourished.
What are the symptoms of measles?
Symptoms usually appear about 7 to 14 days after infection. The illness generally starts with fever and respiratory symptoms rather than the rash that most people associate with measles.
Early symptoms can include:
- High fever
- Cough
- Runny nose
- Red, watery eyes
- Small white spots inside the mouth, known as Koplik spots
The rash usually appears several days after these symptoms begin. It commonly starts on the face and upper neck before spreading downward to the trunk, arms and legs. The rash can last for several days before gradually fading.
This progression matters because someone with measles can already be contagious before the rash appears. Infected people can generally spread the virus from four days before the rash develops until four days afterward.
How does measles spread?
Measles spreads primarily through the air when an infected person coughs, sneezes or breathes. The virus can remain infectious in the air for up to two hours after an infected person has left an area, which helps explain why measles can spread so efficiently.
The virus is highly contagious among people who are not immune. According to the WHO, about 90% of susceptible people who come into close contact with someone who has measles will become infected.
This also means that a person does not necessarily need prolonged physical contact with someone who has measles to be exposed. Being in the same indoor space can be enough.
Can measles cause complications?
Yes. Most people recover from measles, but the infection can cause serious complications, and some can be life-threatening.
Possible complications include:
- Pneumonia
- Ear infections
- Severe diarrhea and dehydration
- Encephalitis, or inflammation of the brain
- Blindness
- Complications during pregnancy
Pneumonia is one of the most common serious complications. Encephalitis is less common but can cause permanent neurological damage. The CDC estimates that about 1 in 1,000 children with measles develops encephalitis.
There is also a rare long-term complication called subacute sclerosing panencephalitis, or SSPE. It affects the central nervous system and can develop years after a person appears to have recovered from measles. SSPE is usually fatal, although it is now very uncommon in countries with widespread measles vaccination.
Also, research has shown that infection can damage immune cells involved in remembering previous infections, leaving people more vulnerable to other infections for months or potentially longer after measles. This phenomenon is sometimes called immune amnesia.
Pregnancy is another situation in which measles can be particularly concerning. Infection during pregnancy can increase the risk of complications for the mother and is associated with premature birth and low birth weight.
How is measles diagnosed?
Measles can be suspected based on the characteristic combination of fever, cough, runny nose, conjunctivitis and rash, particularly when there has been a known exposure or measles is circulating in the community.
But since other infections can cause similar symptoms, laboratory testing may be used to confirm the diagnosis. If you think you or your child may have measles, it is important to call a healthcare provider before going to a clinic or hospital rather than arriving without warning. This allows the healthcare team to take precautions to prevent exposing other patients and staff.
Is there a treatment for measles?
There is no specific antiviral treatment routinely used to eliminate the measles virus. Treatment focuses on supportive care, including fluids, nutrition and management of symptoms and complications.
Depending on the person's condition, medical care may include:
- Fluids to prevent or treat dehydration
- Treatment for fever and other symptoms
- Antibiotics when a bacterial complication, such as certain cases of pneumonia or an ear infection, develops
- Vitamin A in children with measles, according to medical guidance
Measles can lower vitamin A levels, even in children who were adequately nourished before becoming ill.
Because of that, WHO recommends vitamin A supplementation for children with measles, to reduce complications involving the eyes and reduce mortality. This should be given under appropriate medical guidance because the dose depends on the child's age and excessive vitamin A can also be harmful.
Finally, the CDC recommends staying home through the fourth day after the rash appears, with additional precautions depending on the situation. People who need emergency care should call the healthcare facility before arriving.
How can measles be prevented?
The most effective way to prevent measles is vaccination. The measles vaccine has been used for decades and is highly effective at preventing infection and the complications associated with the disease.
In the United States, the routine childhood schedule consists of two doses of the measles, mumps, and rubella vaccine, commonly called MMR. The first dose is recommended at 12 to 15 months of age and the second at 4 to 6 years. People who do not have evidence of immunity may need vaccination outside the routine childhood schedule, depending on their age, vaccination history, risk factors, and circumstances.
Recommendations may also differ for international travelers and during measles outbreaks.
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