About 30% of measles cases develop one or more complications, including
Pneumonia, which is the complication that is most often the cause of death in young children.
Ear infections occur in about 1 in 10 measles cases and permanent loss of hearing can result.
Diarrhea is reported in about 8% of cases.
These complications are more common among children under 5 years of age and adults over 20 years old.
Even in previously healthy children, measles can be a serious illness requiring hospitalization. As many as 1 out of every 20 children with measles gets pneumonia, and about 1 child in every 1,000 who get measles will develop encephalitis. (This is an inflammation of the brain that can lead to convulsions, and can leave the child deaf or mentally retarded.) For every 1,000 children who get measles, 1 or 2 will die from it. Measles also can make a pregnant woman have a miscarriage, give birth prematurely, or have a low-birth-weight baby.
In developing countries, where malnutrition and vitamin A deficiency are common, measles has been known to kill as many as one out of four people. It is the leading cause of blindness among African children. Measles kills almost 1 million children in the world each year.
SSPE (subacute sclerosing panencephalitis)
SSPE is a very rare, but fatal degenerative disease of the central nervous system that results from a measles virus infection acquired earlier in life. Analysis of data from an outbreak of measles in the United States during 1989-1991 suggests a rate of 4-11 cases of SSPE per 100,000 cases of measles. A risk factor for developing this disease is measles infection at an early age. Studies in the United Kingdom indicate that 18 out of every 100,000 people who get measles when they are less than a year old will develop SSPE. This is compared to 1.1 per 100,000 in those infected after 5 years of age. On average, the symptoms of SSPE begin 7 to 10 years after measles infection, but they can appear anytime from 1 month to 27 years after infection.
The first signs of SSPE may be changes in personality, a gradual onset of mental deterioration and myoclonia (muscle spasms or jerks). The diagnosis of SSPE is based on signs and symptoms and on test results, such as typical changes observed in electroencephalographs, an elevated anti-measles antibody (IgG) in the serum and cerebrospinal fluid, and typical histologic findings in brain biopsy tissue.
SSPE progresses in stages, which can vary from person to person. In some cases, the cognitive decline may continue for years before progression to more severe neuromuscular disorders are observed, and thus the diagnosis may be delayed or missed. There are reports of remission and some treatments are available; however, the average survival is one to two years.
All of the genetic analyses of viral material derived from brain tissue of SSPE patients have revealed sequences of wild-type measles virus, never vaccine virus. There is no evidence that measles vaccine can cause SSPE. Cases of SSPE in patients who have a history of measles vaccination but no knowledge of having had measles either had an undiagnosed rash illness or possibly a mild measles infection early in life due to the presence of maternal antibody. Therefore, physicians should consider SSPE in the differential diagnosis of encephalitis even when the patient does not have a history of measles.