Measles
is a highly contagious viral infection caused by the measles virus, a so-called
paramyxovirus.
The virus is spread, typically in winter and spring, by direct contact with nasal or throat secretions of an infected person or, less commonly, by droplets suspended in the air. Measles is contagious beginning 1-2 days before the onset of symptoms, 3-5 days before the rash, and four days after the appearance of the rash.
Symptoms include:
- Fever (often high)
- Runny nose
- Red eyes
- Cough
- A distinctive rash
Symptoms usually begin within 8-12 days following exposure; the rash lasts about 4-6 days, but full recovery can take 7-10 days. In severe cases (or in immunocompromised patients),
subacute sclerosing panencephalitis
(serious brain infection) or
pneumonia
(lung infection) may occur when recovering from measles. Permanent brain damage and death are extremely rare in the developed world.
Once a common childhood illness, there are now fewer cases of measles in the United States (there were only 56 reported cases in 2003), due to the widespread use of the measles vaccine. The childhood and adolescent immunization program has resulted in a greater than 99% decrease in the reported incidence of measles since the vaccine was introduced in 1963.
Despite its success, there continue to be periodic measles outbreaks in the US. Although it is very unlikely to contract measles if properly immunized as a child, unvaccinated or inadequately vaccinated individuals are at increased risk of measles if they:
- Live in crowded and/or unsanitary conditions
- Travel to less developed countries where measles is common
-
Are immunocompromised (eg, untreated
HIV), even if previously vaccinated
People born after 1956 that have never been diagnosed with measles or only received an inactivated or killed vaccine prior to 1968 are also at increased risk (today's live vaccines are much more effective).
Because measles is caused by a virus, it cannot be treated with antibiotics. Efforts are focused on relieving the symptoms until the infection runs its natural course. Such measures include:
- Gargling with warm salt water
- Cool mist humidification
- Lukewarm sponge baths
-
Plenty of fluids and nonaspirin, fever-reducing medications
- Note: Aspirin should never be used in children and teens suspected of having a current or recent viral infection.
In areas of the world where nutritional deficiencies are common, vitamin A has been shown to reduce the severity of measles.
The measles vaccine consists of live measles viruses made in chicken embryo cells. The viruses found in the vaccine have been rendered harmless (attenuated) during the manufacturing process.
Although it is available as a single vaccine, it is normally given in combination with the
mumps
and
rubella
vaccines (MMR) or the mumps, rubella, and
varicella
(chicken pox) vaccine (MMRV). The vaccine is given subcutaneously (under the skin) at a dose of 0.5 ml by a nurse or similar healthcare professional; it must be kept refrigerated and in the dark prior to administration.
All children (with few exceptions) should receive the measles vaccine two times: at 12-15 months and again at 4-6 years (school entry). The second dose can be given earlier, but the two doses must be separated by at least four weeks.
Infants 6-11 months old can receive their first dose if they are exposed to a measles epidemic or are planning to travel internationally. However, they still should receive the other two doses as normally scheduled for a total of three doses.
Children 4-12 years old and high school students who received only one dose after 12 months of age should receive a second dose. All older teens and adults should be vaccinated unless they meet one of the following criteria for measles immunity (protection):
- Documentation of two live attenuated measles vaccines after their first birthday and spaced at least four weeks apart
- Documentation of physician-diagnosed measles
- Blood test indicated immunity to measles
- Born before 1957
The vast majority of individuals tolerate the measles vaccine without any side effects. The most common side effects are a significant fever (103 ºF or higher) lasting up to five days and/or a temporary rash, which occur in 5%-15% of vaccine recipients.
Localized allergic reactions (redness and swelling) at the injection site may uncommonly occur; while anaphylaxis (life-threatening widespread allergic reaction) is extremely rare. Other more serious complications, also extremely uncommon, include:
- Temporary thrombocytopenia (low platelet count)–1 in 25,000 to 1 in 2 million vaccinations
- Encephalitis
or encephalopathy (inflammation or other abnormality of the brain)–1 in 1 million vaccinations
- Seizures–in children predisposed to febrile seizures (convulsion during high fevers)
The vast majority of children and teens can and should receive their vaccinations on schedule. However, individuals in whom the risks of vaccination outweigh the benefits include:
-
Severely immunocompromised patients (eg, active
AIDS
patients)–HIV-positive individuals who are doing well, however,
should
receive the vaccine since measles can be serious and often fatal in HIV patients
- Pregnant women–pregnancy should be avoided for at least one month after receiving the measles vaccine
- Previous severe allergic reaction (ie, anaphylaxis) to the vaccine or one of its constituents (most commonly gelatin or the antibiotic neomycin); in some cases the vaccine can be safely given after treatment
- Previous thrombocytopenia clearly related to the vaccine
Since unvaccinated individuals are susceptible to measles, all household and other close contacts of these individuals must be vaccinated or carry documentation of either measles immunity or previous infection.
In some cases, the vaccine should be delayed, but ultimately given. Such cases include:
- Children experiencing a significant illness with fever–the vaccine can be safely given in the presence of a minor respiratory illness
- Recent immunoglobulin (ie, antibody) or corticosteroids therapy
Isolating those with any contagious disease has long been the main approach to preventing its spread. It is essential, for example, to keep children with measles at home until the illness has run its course.
Unvaccinated household contacts may receive immunoglobulin (ready made antibodies against measles), which may prevent or at least modify measles if given within six days of exposure. This is especially important in children less than one year old, pregnant women, and immunocompromised individuals, all of whom are at particular risk for a complicated case of measles. Immunoglobulin is not for those who have received at least one vaccination after 12 months of age unless they are immunocompromised.
First of all, it is essential for every suspected case of measles to be promptly reported, so public health authorities can quickly determine that an outbreak has taken place. If you think your child may have measles, contact your doctor immediately even if you think he or she is not very sick.
In the event of a suspected or confirmed measles outbreak, all individuals who were potentially exposed to a measles case within the past two weeks should be vaccinated unless they meet the criteria for immunity described above. This would include all those living in the same household as the infected person, as well as all those attending the infected person’s childcare facility, school, college, or other institution.
Previously unvaccinated individuals who receive the vaccination within 72 hours of exposure may return to their normal activities, but those who are not, must remain isolated for at least two weeks so that they do not develop the infection.
