Measles

Bacteriology at UW- Madison

The Microbial World

University of Wisconsin - Madison

Measles

Measles

Measles (rubeola) is one of the most infectious diseases known. Prior to widespread immunization, measles was a common childhood disease, with greater than 90% of infants and children infected by 12 years of age.

Since vaccine usage was begun in 1963, efforts to eliminate measles in the United States have resulted in record low numbers of reported cases. Since 1997, measles has not been endemic in the United States. The measles virus does not circulate in the United States except in limited outbreaks following importation from other countries. The risk of exposure to measles in the United States is low because of the high population immunity achieved through vaccination. However, the risk of exposure to measles outside the United States can be high. Measles remains a common disease in many developing countries and in some developed countries in Europe and Asia.

Measles Virus

Measles virus is an enveloped ss (-)RNA virus, a member of the paramyxovirus family, which also includes mumps virus, respiratory syncycial virus (RSV) and the caninie distemper virus (CDV) of dogs and cats. Its natural host is humans and monkeys.

Pathogenesis of Measles

The pathogenesis of measles resembles the general pattern for smallpox. The disease presents with cough, runny nose, fever, red eyes and white spots (Koplick spots) inside the mouth. This is followed 3 to 7 days later by a red blotchy skin rash, which spreads from the face to the rest of the body. The rash usually lasts 4 - 7 days but can persist for up to 3 weeks. Measles is frequently complicated by middle ear infection or diarrhea. The disease can be severe, with bronchopneumonia or brain inflammation (encephalitis) leading to death in approximately 2 of every 1,000 cases in developed countries. In the developing world, case-fatality rates often exceed 150 deaths per 1000 cases.

A characteristic red, blotchy rash appears around the third day of illness, beginning on the face and becoming generalized. The skin rash of measles is an allergic response to virus products in the body rather than direct viral multiplication in skin cells. www.info.gov.hk/dh/diseases/CD/Measles.htm

Koplick spots are a characteristic of measles used in diagnosis. They appear opposite the molars as red spots with blue white centers. www.info.gov.hk/dh/diseases/CD/Measles.htm

Transmission

Measles is spread by respiratory droplets or by direct contact with nasal or throat secretions of infected persons, and less commonly, by articles contaminated with nose and throat secretions. Measles is one of the most highly communicable infectious diseases known. The patient can pass the disease to other persons from beginning of the disease to 4 days after appearance of the rash. The incubation period before the disease varies from 7 to 18 days, usually around 14 days.

Treatment

There is no specific antiviral therapy for measles, and the basic treatment consists of providing necessary supportive therapy such as hydration and antipyretics and treating complications such as pneumonia. Multiple studies have shown that vitamin A supplementation improves outcome of measles in communities where vitamin A deficiency is known to occur. Although vitamin A deficiency is not a major problem in the United States, low serum concentrations have been found in children with severe measles. Therefore, the American Academy of Pediatrics recommends vitamin A supplementation be considered for children 6 months of age and older.

Prevention

Measles vaccine contains live, attenuated measles virus. It is available as a single-antigen preparation or combined with live, attenuated mumps or rubella vaccines, or both. Combined measles, mumps, and rubella (MMR) vaccine is recommended whenever one or more of the individual components are indicated.

The recommended routine age for measles vaccination of infants in the United States is 12-15 months. A single dose of MMR vaccine induces antibody formation to all three viruses in at least 95% of susceptible persons vaccinated at 12 months of age or older. A second dose is expected to induce immunity in most vaccinees who do not respond to the first dose. The second dose should be separated from the first by at least 28 days and is routinely administered at 4-6 years of age.

Immunity to measles is considered permanent. Most persons born before 1957 have had measles disease and are generally not considered to be susceptible. However, measles or MMR vaccine may be given to these persons if there is reason to believe they might be susceptible.

Measles Websites
CDC National Immunization Program: Measles
CDC Yellow Book: Measles (Rubeola)
MedlinePlus: Measles