Measles

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Measles
H9991083.jpg

How Measles affects the skin.
ICD-10 B05.-
ICD-O: {{{ICDO}}}
ICD-9 055
OMIM {{{OMIM}}}
MedlinePlus 001569
eMedicine derm/259
DiseasesDB 7890
How to read a taxoboxMeasles virus
Measles virus
Measles virus
Virus classification
Group: Group V ((-)ssRNA)
Order: Mononegavirales
Family: Paramyxoviridae
Genus: Morbillivirus
Species: Measles virus

Measles, also known as rubeola, is a very highly contagious [[virus|viral] disease caused by a paramyxovirus of the genus Morbillivirus, and characterized by a high fever and characteristic skin rash. Other names for measles are five-day measles, hard measles, and even seven-day, eight-day, nine-day, or ten-day measles. This is in contrast to unrelated German measles or rubella, which is caused by the rubella virus and often is known as the three-day measles. Before the advent of vaccines, measles was a very common childhood disease, with nearly everyone infected by age ten to twelve (Breslow 2002). Immunity is lifelong following infection and is considered to be lifelong following immunization.

In developed countries, measles usually is not severe, although it can lead to such complications as encephalitis, pneumonia, diarrhea, and ear infections. In developing countries, it is much more serious with about one million deaths annually during the 1990s and a fatality rate as high as 25 percent (Breslow 2002). In the developing world, measles also is a common cause of blindness (Breslow 2002).

Measles is serious enough in the developing world that there is a saying among mothers, "never count your children until after the measles" (Dillner 2001). However, measles is also a disease that is highly preventable. Due to human ingenuity and creativity, a vaccine has been developed which is highly effective. However, public health depends on individuals fulfilling their responsibility to inoculate their children, so they do not catch the disease and spread it. Likewise, there is a social responsibility for those individuals and societies with means to assist those without access to the vaccine.

Contents

Overview

Reports of measles go as far back to at least 600 B.C.E.; 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, Smallpox and Measles (in Arabic: Kitab fi al-jadari wa-al-hasbah). In 1954, the virus causing the disease was isolated from an 11-year old boy in the United States and adapted and propagated on chick embryo tissue culture (EPI 1980). To date, 21 strains of the measles virus have been identified (Rima et al. 1995).

Measles is caused by a type of virus known as a paramyxovirus. Paramyxoviruses are viruses of the Paramyxoviridae family of the Mononegavirales order. They are negative-sense, single-stranded RNA viruses responsible for a number of human and animal diseases. The measles virus (MV) is an enveloped, nonsegmented negative-stranded RNA virus. Humans are the only known natural hosts of measles, although the virus can infect some non-human primate species. The virus survives only hours outside the body (Breslow 2002).

Measles is spread primarily through the respiratory system, through contact with fluids from an infected person's nose and mouth, either directly or through aerosol transmission. Once transmission occurs, the virus infects the epithelial cells of its new host, and may also replicate in the urinary tract, lymphatic system, conjunctivae, blood vessels, and central nervous system (Flint et al. 2004).

Measles is one of the world's most contagious diseases—about 90 percent of people without immunity, sharing a house with an infected person, will catch it. Longe (2006) reports that approximately 85 percent of people exposed to the virus become infected and 95 percent of these people develop the actual illness. Once infected with the virus, there is a delay of seven to eighteen days before the person actually becomes ill (Longe 2005). The most contagious time period begins three to five days before the person actually becomes ill and the characteristic rash appears, until about four days after the measles rash has appeared (Longe 2005).

Measles can be very serious, particularly in developing countries where the fatality rate can be as high as 15-25 percent (Breslow 2002). One million deaths annually were attributed to this disease in the developing world during the 1990s (Breslow 2002). Deaths are often caused by secondary infections such as pneumonia or diarrhea, with blindness also a common complication (Breslow 2002). In the developing world, measles usually is not severe, but can lead to serious complications, including diarrhea (8 percent of cases), ear infections (7 percent), and pneumonia (6 percent), and more rarely, encephalitis (0.1 percent) and subacute sclerosing panencephalitis (0.001 percent), with a fatality rate of about 0.2 percent (Breslow 2002). While only one in one thousand measles suffers develop encephalitis, ten to fifteen percent of these will die and another twenty-five percent will have permanent brain damage (Longe 2006).

There also may be inflammation of the liver, appendix, intestine, or intestinal lymph nodes, and rarely inflammations of the heart or kidneys (Longe 2006).

Subacute sclerosing panencephalitis is a very rare complication of measles that can occur up to ten years after the initial infection (Longe 2006). It involves the slow, progressive, swelling and destruction of the entire brain, with concommitent symptoms (change in personality, decreased intelligence with school problems, decreased coordination, spikes in temperature, possible blindness, etc.), and is inevitably fatal (Longe 2006). It is most common among those who have had measles prior to the age of two (Longe 2006).

Licensed vaccines to prevent the disease became available in 1963. This vaccine has been shown to be about 95 percent effective in the United States when administered between the recommended ages of twelve to fifteen months (Breslow 2002). Prior to immunization programs, major measles outbreaks usually occurred on a two to three-year cycle, with smaller outbreaks in the off years (Longe 2006).

Symptoms

The classical first symptoms of measles include a fever for at least three days, and the three Cs—cough, coryza (runny nose), and conjunctivitis (red eyes). The fever may reach up to 104° Fahrenheit (40° Celsius). A few days later, there is the appearance of Koplik's spots, which are unique to measles (Longe 2006). This is a rash that consists of tiny white dots on a reddish bump and that appears in the mouth, and in particular the mucous membrane that lines the cheeks (Longe 2006). Although Koplik's spots are pathognomonic (diagnostic) for measles, they are not often seen, even in real cases of measles, because they are transient and may disappear within a day of arising.

Within a couple of days after the Koplik's spots appear, the characteristic measles rash begins, which starts on the head, face, and neck and proceeds to the trunk, then the abdomen, and then to the arms and legs (Longe 2005). The rash is classically described as a generalized, maculopapular, erythematous rash. The rash starts out as flat patches but may develop some bumps and often causes itching. At the time of the presence of the rash, the fever usually climbs higher, and there may be nausea, vomiting, diarrhea, and swollen lymph nodes, and a more problematic cough (Longe 2006). The rash is said to "stain," changing color from red to dark brown, before disappearing. It usually last five days and may leave the skin dry and flaky (Longe 2006).

Diagnosis and treatment

Clinical diagnosis of measles requires a history of fever of at least three days together with at least one of the three Cs. Observation of Koplik's spots is also diagnostic of measles.

Alternatively, laboratory diagnosis of measles can be done with confirmation of positive measles IgM antibodies or isolation of measles virus RNA from respiratory specimens. In cases of measles infection following secondary vaccine failure, IgM antibody may not be present. In these cases, serological confirmation may be made by showing IgG antibody rises by enzyme immunoasay or complement fixation.

Positive contact with other patients known to have measles adds strong epidemiological evidence to the diagnosis.

There is no specific treatment or antiviral therapy for stopping uncomplicated measles. Most patients with uncomplicated measles will recover with rest and supportive treatment. Treatment is designed to make the patient comfortable and watch for complications; fever and pain can be treated with acetaminophen (Longe 2005).

Some patients will develop pneumonia as a sequela to the measles. Histologically, a unique cell can be found in the paracortical region of hyperplastic lymph nodes in patients affected with this condition. This cell, known as the Warthin-Finkeldey cell, is a multinucleated giant with eosinophilic cytoplasmic and nuclear inclusions.

Care such as oral rehydration therapy for diarrhea and respiratory care for patients with pneumonia can be used for complications, and high-dose vitamin A therapy is recommended by the World Health Children for children in developing nations in order to reduce mortality and prevent blindness (Breslow 2002).

Prevention

The vaccine developed for measles is highly effective. It is made of live measles virus that have been treated so that cause the individual's immune system to react and produce antibodies and yet cannot cause actual infection (Longe 2006).

The vaccine is usually given at the age of 15 to 18 months. In developed countries, most children are immunized against measles at around the age of 18 months, generally as part of a three-part MMR vaccine (measles, mumps, and rubella). Prior to this, the baby's immune system is too weak to confer long-term protection against the virus (Longe 2006). Children younger than 18 months usually retain anti-measles immunoglobulins (antibodies) transmitted from the mother during pregnancy and thus are protected.

Because of the seriousness of the disease, a repeat "booster" injection is usually given at a later age to ensure protection, perhaps between the ages of four and five or up the ages of ten or eleven years of age.

Public health

Measles is a significant infectious disease because, while the rate of complications is not high, the disease itself is so infectious that the sheer number of people who would suffer complications in an outbreak among non-immune people would quickly overwhelm available hospital resources. If vaccination rates fall, the number of non-immune persons in the community rises, and the risk of an outbreak of measles consequently rises.

Since the development of an effective vaccine, there has been a goal to eradicate measles globally, as happened to smallpox, particularly since humans are the only reservoir for the virus and the virus survives only hours in the environment (Breslow 2002).

Vaccination rates have been high enough to make measles relatively uncommon in the developed world. Even a single case in a college dormitory or similar setting is often met with a local vaccination program, in case any of the people exposed are not already immune. In developing countries, measles remains common.

Unvaccinated populations are at risk for the disease. After vaccination rates dropped in northern Nigeria in the early 2000s, due to religious and political objections, the number of cases rose significantly, and hundreds of children died (OCHA 2005). A 2005 measles outbreak in Indiana (United States) was attributed to children whose parents refused vaccination (Parker et al. 2006). 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 (Dillner 2001). This practice poses a variety of health risks to the child, and has been discouraged by the public health authorities (Dillner 2001). Scientific evidence provides no support for the hypothesis that MMR plays a role in causing autism (Rutter 2005). Declining immunization rates in the UK are the probable cause of a significant increase of cases of measles (Henry 20070.

According to the World Health Organization (WHO), measles remains a leading cause of vaccine preventable childhood mortality. It is serious enough that Dillner (2001) states that in the developing world, mothers say, "never count your children until after the measles." However, worldwide the fatality rate has been significantly reduced by partners in the Measles Initiative: The American Red Cross, the United States Centers for Disease Control and Prevention (CDC), the United Nations Foundation, UNICEF, and the World Health Organization (WHO). Globally, measles deaths are down 60 percent, from an estimated 873,000 deaths in 1999 to 345,000 in 2005. Africa has seen the most success, with annual measles deaths falling by 75 percent in just 5 years, from an estimated 506,000 to 126,000 (UNICEF 2007).

The joint press release by members of the Measles Initiative brings to light another benefit of the fight against measles: "Measles vaccination campaigns are contributing to the reduction of child deaths from other causes. They have become a channel for the delivery of other life-saving interventions, such as bed nets to protect against malaria, de-worming medicine, and vitamin A supplements. Combining measles immunization with other health interventions is a contribution to the achievement of Millennium Development Goal Number 4: A two-thirds reduction in child deaths between 1990 and 2015" (UNICEF 2007).

Outbreaks are still occurring, however. For example, in June 2006, there was an outbreak in Boston, which resulted from a resident who had recently visited India (Smith 2006). As of 2006, endemic cases were still being reported in Bolivia, Brazil, Colombia, Guatemala, Mexico, Peru, and Venezuela. Most recently, in 2007, Japan has become a nexus for measles, suffering a record number of cases, and a number of universities and other institutions in the country have closed in an attempt to contain the outbreak (Fukumimi 2007).

References

  • Breslow, L. 2002. Encyclopedia of Public Health. New York: Macmillan Reference USA/Gale Group Thomson Learning. ISBN 0028658884
  • Dillner, L. 2001. The return of the measles party. Guardian July 26, 2001. Retrieved September 11, 2007.
  • Expanded Program on Immunization in the Americas (EPI). 1980. Live attenuated measles vaccine. EPI Newsl. 2(1):6. Retrieved September 11, 2007.
  • Flint, S. Jane. 2004. Principles of Virology: Molecular Biology, Pathogenesis, and Control of Animal Viruses. Washington, D.C.: ASM Press. ISBN 1555812597
  • Fukumimi, S. 2007. Measles outbreak hits Japanese universities. Fukumimi.WordPress May 22, 2007. Retrieved September 11, 2007.
  • Henry, E. 2007. MMR plea as measles cases treble in 11 weeks. Telegraph. Retrieved September 11, 2007.
  • Longe, J. L. 2006. The Gale Encyclopedia of Medicine. Detroit: Thomson Gale. ISBN 1414403682
  • Longe, J. L. 2005. The Gale Encyclopedia of Cancer: A Guide to Cancer and Its Treatments. Detroit: Thomson/Gale. ISBN 1414403623
  • Office for the Coordination of Humanitarian Affairs, United Nations (OCHA). 2005. Measles kills more than 500 children so far in 2005. IRIN. September 11, 2007.
  • Parker, A., W. Staggs, G. Dayan et al. 2006. Implications of a 2005 measles outbreak in Indiana for sustained elimination of measles in the United States. N Engl J Med 355(5): 447–455.
  • Rima, B. K., J. A. Earle, R. P. Yeo, L. Herlihy, K. Baczko, V. ter Muelen, J. Carabana, M. Caballero, M. L. Celma, and R. Fernandez-Munoz. 1995. Temporal and geographical distribution of measles virus genotypes. J Gen Virol 76: 1173-1180.
  • Rutter, M. 2005. Incidence of autism spectrum disorders: Changes over time and their meaning. Acta Paediatr 94(1): 2–15.
  • Smith, S. 2006. Measles outbreak shows a global threat. Boston Globe June 10, 2006. Retrieved September 11, 2007.
  • UNICEF. Global goal to reduce measles deaths in children surpassed. UNICEF Joint Press Release January 19, 2007. Retrieved September 11, 2007.


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