Measles is an infectious viral disease that occurs most often in the late winter and spring. It begins with a fever that lasts for a couple of days, followed by a cough, runny nose, and conjunctivitis (pink eye). A rash starts on the face and upper neck, spreads down the back and trunk, then extends to the arms and hands, as well as the legs and feet. After about five days, the rash fades the same order it appeared.
Infected people are usually contagious from about four days before their rash starts to appear. The virus resides in the mucus in the nose and throat of infected people. When they sneeze or cough, droplets spray into the air and remain active and highly contagious on infected surfaces for up to two hours.
Although measles itself is unpleasant, the complications are more dangerous. Six to 20 percent of the people who get the disease will get an ear infection, diarrhea, or pneumonia (which occurs in up to 6% of reported measles casa and accounts for 60% of deaths from measles). One out of 1000 people with measles will develop inflammation of the brain, and about one out of 1000 will die.
This disease is rarely seen in children below 3 years of age. It is most unusual before 6 months due to the protection provided by the mother's antibodies acquired while in the womb. After 6 months of age these antibodies start waning and a child becomes susceptible to measles.
The measles virus is a cytopathic virus belonging to the family Paramyxoviridae, genus Morbillivirus. The virus continues to be an important human pathogen. Although it is largely controlled by immunisation in developed countries, it causes significant morbidity and mortality in developing ones.
Origins and discovery
The measles virus is believed to have evolved from rinderpest (or a similar animal virus) 4000-5000 years ago, when Babylonian cities grew large enough to support continuous person-to-person transmission and thus maintain the virus.
Reports of measles go as far back to at least 600 B.C. However, the first scientific description of the disease and its distinction from smallpox is attributed to the Persian physician Ibn Razi (Rhazes) 860-932, who published a book entitled The Book of Smallpox and Measles (in Arabic: Kitab fi al-jadari wa-al-hasbah). In 1954, measles appeared in the United States and with it the beliefs that the virus migrates indirectly or directly from Europe, Africa, and Asia.
Causes and symptoms
|Group||Group V ((-)ssRNA)|
Measles is caused by a type of virus called paramyxovirus. It is an extremely contagious infection, spread through the tiny droplets that may spray into the air when an individual carrying the virus sneezes or coughs. About 85% of those people exposed to the virus will become infected with it. About 95% of those people infected with the virus will develop the illness called measles. Once someone is infected with the virus, it takes about 7-18 days before he or she actually becomes ill. The most contagious time period is the three to five days before symptoms begin through about four days after the characteristic measles rash has begun to appear.
The classical symptoms of measles include:
- a fever for at least three days
- high fever—up to 40 °C (104 °F)
- the three "C"s: cough, coryza (runny nose), and conjunctivitis (pink or red eyes)
- tiny white spots inside the month known as Koplik's spot
- a red, slightly bumpy rash
- red, swollen, and sore throat
The rash is classically described as a generalised, maculopapular, erythematous rash that begins several days after the fever starts. It starts on the head before spreading to cover most of the body, often causing itching. The rash is said to "stain", changing color from red to dark brown, before disappearing.
A measles case is usually confirmed with a blood test for measles antibodies, though if a person with symptoms is a known contact of a confirmed case, a clinical diagnosis is sufficient. The measles virus can be cultured from infected respiratory secretions, the eye, the blood, or the urine during the acute phase of the illness. The usual reason to recover measles virus from a person is to identify the viral strain in order to trace the source of an importation.
Complications and effects
It suppresses the immunity and makes the child prone to getting pneumonia and diarrhea. Many patients (about 5-15%) develop other complications such as ear infections and sinus infections, especially in children. Other viral infections may also strike the patient, including croup, bronchitis, laryngitis, or viral pneumonia. Inflammation of the liver, appendix, intestine, or lymph nodes within the abdomen may cause other complications. Rarely, inflammations of the heart or kidneys, a drop in platelet count (causing episodes of difficult-to-control bleeding), or reactivation of an old tuberculosis infection can occur.
An extremely serious complication of measles infection is the swelling of the brain (encephalitis). This can occur up to several weeks after the basic measles symptoms have resolved. About one out of every thousand patients develops this complication, and about 10-15% of these patients die. Symptoms include fever, headache, sleepiness, seizures, and coma. Long-term problems following recovery from measles encephalitis may include seizures and mental retardation.
Because of limited disease surveillance and death registration in many countries with weak infrastructure and high measles burden, current routine reporting systems are inadequate for monitoring global measles mortality. Different modeling approaches have been used to estimate the global number of measles deaths. Overall, in roughly last 150 years, measles has been estimated to have killed about 200 million people worldwide.
There is no specific treatment for measles. However, measles can be prevented by immunisation. About 95% of vaccinated persons are protected with one dose, and practically everyone is protected with two doses. Licensed vaccines to prevent the disease became available in 1963. All children, including those who were born before 1979, should be vaccinated to protect themselves and others from measles.
On the basis of results from the natural history model, overall global measles mortality decreased 39%, from 873,000 deaths (uncertainty bounds: 645,000-1,196,000 deaths) in 1999 to 530,000 deaths (bounds: 383,000-731,000 deaths) in 2003. The largest reduction was in Africa, where estimated measles mortality decreased by 46% during this period.
In the early 2000s the MMR vaccine controversy in the United Kingdom regarding a potential link between the combined MMR vaccine (vaccinating children from mumps, measles and rubella) and autism prompted a comeback in the measles party, where parents deliberately infect the child with measles to build up the child's immunity without an injection. This practice poses many health risks to the child, and has been discouraged by the public health authorities. Scientific evidence provides no support for the hypothesis that MMR plays a role in causing autism. Declining immunisation rates in the UK are the probable cause of a significant increase of cases of measles, 2006 being the highest on record, and 2007 already showing an increase on the previous year.
If measles is suspected, a health care provider should be contacted. The health care provider can confirm the diagnosis and provide home care instructions to relieve the discomfort of the symptoms.