Disease
Measles
Author
Peggy Engel, BIOL 230, Spring 2009
Causative Agents
The measles virus is part of the Paramyxovirus Family which includes the parainfluenza virus1 and the parainfluenze virus3. These viruses have: a ( – ) RNA strand, a helical shape, and an envelope.
Epidemiology
When a person becomes infected with the measles virus, because there is only one serotype (def), a single infection will mean the person will then have lifelong immunity to this virus. When infected, there are almost always visible signs.
Since 1963 when the measles vaccine was introduced to school age children, reported cases of measles has dropped by 99%. Most recently there was an outbreak from 1989 to 1991 causing 123 deaths after affecting more than 55,000 people. In 1993, vaccinations were introduced which again lowered the number of cases. Since 2002, the number of reported cases is so low it is no longer considered endemic (def) in the United States; however, not vaccinating children in the US would still cause them to be at risk of getting the disease if it were brought in to the country. Worldwide, measles is still a problem with the majority of the 30 million reported cases coming from Africa.
Measles affects all age groups, but older adults and children younger than 5 seem to be the hardest hit. People with compromised immune systems can develop giant cell pneumonia (def) because of the continued growth in the lungs. Pneumonia is responsible for 60% of the deaths that occur with measles. Also, secondary infections such as otitis media (def) are common because of the virus growing in the epithelial cells.
Another complication that may occur is encephalitis (def). Although 90% recover from this, other complication such as deafness, mental disorders or seizures may occur.
There is no evidence race affects susceptibility.
Malnourishment will cause the virus to produce more severe complications as well as vitamin A deficiencies, pregnancy and already immune compromised systems.
Transmission
Measles in highly contagious and is spread through contact with respiratory droplets; the aerosol route and droplets being inhaled. Initial infection occurs in the epithelial cells of the upper and lower respiratory tract. Infection can spread to lymph tissue. This can lead to viremia (def) and the spread of the virus to organs before a symptomatic rash appears. As the disease appears one to two weeks after infection, it can be spread without knowledge.
Signs and Symptoms
As this virus causes respiratory infections, a running nose and cough will appear. A fever of 101 degrees or above is common. Conjunctivitis (def) occurs. Koplik’s spots (def) on the buccal mucosa (def) appear before the appearance of a rash on the face, trunk and extremities. Uncomplicated measles last from 7 to 10 days.
Prevention and Treatment
Currently, the vaccine being used to treat measles works very well. A single dose, when given to children after 12 months of age, provides a 95% protective immunity. If a person does become infected, a natural immunity is built and they will never again contract the disease. Vitamin A treatments for children with vitamin A deficiencies reduces mortality. There is no antiviral treatment for measles; however, if secondary complications occur they should be treated appropriately.
Bibliography
Chen, Selina. "Measles: eMedicine Pediatrics: General Medicine." EMedicine The Continually Updated Clinical Reference. 17 Jan. 2008. 12 Apr. 2009 <http://emedicine.medscape.com/article/966220-overview>.
"Mumps and Measles." Biomedical Sciences Graduate Program. 23 Oct. 2008. University of South Carolina School of medicine. 12 Apr. 2009 <http://pathmicro.med.sc.edu/mhunt/mump-meas.htm>.