Measles was declared eradicated in the U.S. in the year 2000, but since then there have been numerous large outbreaks.

The classic teaching is that measles infection is characterized by cough, coryza, conjunctivitis in addition to fevers. Patients may develop koplik spots which are whitish, grayish, or bluish lesions seen on the buccal mucosa. The measles rash classically starts on the face and hairline and spreads downwards.

Koplik spots are seen at the beginning of illness and often have slough away when the exanthem appears.

The measles virus is transmitted by direct contact with infectious droplets or by airborne. Measles virus can remain infectious in the air for up to two hours after an infected person leaves an area.

Most measle deaths are due to respiratory tract complications or encephalitis. The risk of complications is increased in developing countries

Subacute sclerosing panencephalitis (SSPE) is s a fatal, progressive degenerative disease of the central nervous system that usually occurs years after natural measles virus infection.

In cases of suspected measles, it is useful to obtain three samples from patients: a serum sample for measles IgM, a throat (or nasopharyngeal) swab for PCR, and a urine sample for PCR.

Serology testing is a common method used for diagnosis of measles infection. Of note, anti-measles IgM is generally detectable three days after the appearance of the rash; it may be undetectable on the day the rash appears.

Detection of measles RNA by PCR is most successful when samples are collected on the first day of rash through the 3 days following onset of rash.

There is no specific antiviral therapy for measles. Supportive care is the most important thing. Severe measles cases, such as those who are hospitalized, should be treated with vitamin A given that vitamin A deficiency is associated with worse outcomes.

Evidence of immunity against measles includes at least one of the following:

Written documentation of adequate vaccination:

Laboratory evidence of immunity (i.e. titiers)

Birth before 1957 (when measles was endemic)

A post-vaccination rash and low-grade fever may occur up to three weeks after receiving the MMR vaccine. It occurs in approximately 5% of children. In the setting of an outbreak, PCR testing helps distinguish between a vaccine-associated reaction and true, wild-type measles.

People exposed to measles who do not have evidence of immunity against it should be offered post-exposure prophylaxis.

MMR vaccine as post-exposure prophylaxis is effective if administered within 72 hours of exposure.

Individuals at risk for severe infection, such as infants younger than 6 months of age, pregnant women without evidence of measles immunity and people with an underlying immunocompromising conditions should receive immunoglobulins. It can be given up to six days after exposure.

One dose of MMR vaccine is approximately 93% effective at preventing measles; two doses are approximately 97% effective.