Measles overview: Difference between revisions
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==Overview== | ==Overview== | ||
Measles is a disease caused by the [[Morbillivirus]]. It is transmitted into the respiratory by contact with infected fluids. Incubation lasts for 4-12 days, during which patients are asymptomatic. Symptomatic onset includes the appearance of a distinct rash. Infected people remain contagious | Measles is a disease caused by the [[Morbillivirus]]. It is transmitted into the respiratory by contact with infected fluids. Incubation lasts for 4-12 days, during which patients are asymptomatic. Symptomatic onset includes the appearance of a distinct rash. Infected people remain contagious from 5 days before appearance to until 4 days after. | ||
==Historical Perspective== | ==Historical Perspective== | ||
Revision as of 19:31, 25 February 2014
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Measles Microchapters |
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Diagnosis |
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Treatment |
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Measles overview On the Web |
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American Roentgen Ray Society Images of Measles overview |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Measles is a disease caused by the Morbillivirus. It is transmitted into the respiratory by contact with infected fluids. Incubation lasts for 4-12 days, during which patients are asymptomatic. Symptomatic onset includes the appearance of a distinct rash. Infected people remain contagious from 5 days before appearance to until 4 days after.
Historical Perspective
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 "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 from the US, David Edmonston, and adapted and propagated on chick embryo tissue culture.[1] To date, 21 strains of the measles virus have been identified.[2] Licensed vaccines to prevent the disease became available in 1963.
Pathophysiology
Measles is a disease caused by a virus , specifically a paramyxovirus of the genus Morbillivirus.
Differentiating Measles from other Diseases
Measles is a disease characterized by the classical clinical triad of cough, coryza and conjunctivitis. In most cases the presentation is classical and the diagnosis can be sufficiently made clinically. However, in a few cases certain other diagnostic possibilities must be kept in mind. These include other viral exanthams such as erythema infectiosum, other maculopapular rashes etc. Also, in areas where killed vaccines are used, the probability of atypical measles with fever, conjunctivitis, pneumonitis and rash must be kept in mind. It is worthwhile to consider Kawasaki's disease, rubella, dengue, systemic lupus erythematosus and serum sickness while considering the diagnosis of measles.
Epidemiology and Demographics
According to the World Health Organization (WHO), measles is a leading cause of vaccine preventable childhood mortality. 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.
Risk Factors
Measles is a disease with very low incidence in the developed world. Lack of vaccination against measles is one of the biggest risk factors that predisposes measles spread. In developed countries like USA, most cases are attributed to unvaccinated or incompletely vaccinated travelers from other parts of the world. Primary vaccine failure occurs in approximately 5% of individuals vaccinated with a single dose of vaccine at 12 months of age or older and also predisposes an individual to the risk of developing measles.
Natural History, Complications and Prognosis
Measles spreads through the air by breathing, coughing or sneezing. It is so contagious that any child who is exposed to it and is not immune will probably get the disease. The virus lives in the mucus in the nose and throat of the infected person. When that person sneezes or coughs, droplets spray into the air. The virus can live on infected surfaces for up to 2 hours and spreads so easily that people who are not immune will probably get it when they come close to someone who is infected. Measles is a disease of humans.
Complications with measles are relatively common, ranging from relatively mild and less serious diarrhea, to pneumonia and encephalitis (subacute sclerosing panencephalitis - SSPE). Complications are usually more severe amongst adults who catch the virus.
Measles itself is unpleasant, but the complications are dangerous. Six to 20 percent of the people who get the disease will get an ear infection, diarrhea, or even pneumonia. One out of 1000 people with measles will develop inflammation of the brain, and about one out of 1000 will die.
Diagnosis
History and Symptoms
The classical 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. Koplik's spots seen inside the mouth are pathognomonic (diagnostic) for measles but are not often seen, even in real cases of measles, because they are transient and may disappear within a day of arising.
Physical Examination
Measles is a condition, that is best diagnosed clinically based on a constellation of signs and symptoms. Koplik's spots, rash and conjunctivitis are 3 major physical findings that must be looked out for, while making the diagnosis of measles.
Laboratory Findings
Measles is a disease best diagnosed clinically, however lab tests have a limited role to play esp. in those conditions where the diagnosis is uncertain and certain cases of atypical pneumonia. Detecting a positive rise in measles IgM antibodies is one of the methods used for laboratory diagnosis of measles. Histologially, a unique cell can be found in the paracortical region of hyperplastic lymph nodes in patients affected with pneumonia secondary to measles. This cell is known as the Warthin-Finkeldey cell. It is helpful in diagnosing measles associated pneumonia.
Chest X Ray
Chest X Ray can be used to diagnose pneumonia, which is one of the complications of measles. It shows consolidation of lung lobes. Damage to the alveoli may occur in severe cases leading to dyspnea.
Treatment
Medical Therapy
There is no specific treatment or antiviral therapy for uncomplicated measles. Most patients with uncomplicated measles will recover with rest and supportive treatment.
Primary Prevention
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."[3]
References
- ↑ Live attenuated measles vaccine. EPI Newsl. 1980 Feb;2(1):6.
- ↑ Rima BK, Earle JA, Yeo RP, Herlihy L, Baczko K, ter Muelen V, Carabana J, Caballero M, Celma ML, Fernandez-Munoz R 1995 Temporal and geographical distribution of measles virus genotypes. J Gen Virol 76:11731180.
- ↑ UNICEF Joint Press Release