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Overview of Measles

What is measles?

Measles is a highly infectious (contagious) disease at the community level and characterized by fever, malaise, cough, coryza (rhinitis), and conjunctivitis followed by a generalized maculopapular rash. It is also called rubeola, red measles, hard measles, and 7-day measles. Measles virus causes measles and which is a single-stranded negative-sense RNA virus of the genus Morbillivirus and the family belongs to Paramyxoviridae.

Epidemiology

Human beings are the only reservoir for this virus; unvaccinated infants who have lost their maternal antibodies account for a large proportion of susceptible individuals.

It is generally most common in childhood, However, as vaccine coverage increases, the age of distribution of the disease shifts upward. In the United States, adolescents and adults are the most probable age groups to acquire measles.

Between 2000 and 2016, the yearly incidence of measles decreased by around 87%. Only one WHO region (Americas) has been verified as having eliminated measles.

Since the elimination of measles in 2000 in the United States, outbreaks in the United States occurred predominantly among knowingly unvaccinated children (in between 59 – 93%).

As of October 2017, 120 new cases of measles reported to CDC from 15 states, striking the number of cases reported in 2016; 65 new confirmed cases were identified in a Somali-American community from Minnesota due to a decrease in MMR vaccination coverage.

Measles has not been endemic in the United state; however, a limited number of cases occur annually due to importations of viruses from endemic countries that contribute to outbreaks.

Despite sporadic outbreaks, the elimination of measles in the United States appears to have been sustained as of 2011 but increasing rates of deliberate under vaccination undermine measles elimination programs.

Infective material: Respiratory secretions of measles cases.

Period of communicability: four days before and five days after the appearance of rashes. It is highly infectious during this time period.

Secondary attack rate: About more than 90 percent.

Mode of transmission: Direct contact with large respiratory droplet infection and droplet nuclei, but the airborne spread is also possible. It is also transmitted by conjunctival route but is a controversial statement.

Risk factors:

Age: Incidence high in children (between 6 months and 3 years) in the case of developing countries. In the developed countries, there is a shift in the age of incidence due to the fact that of high immunization coverage.

Immunity: One attack of measles confers lifelong immunity and second attacks are rare. Immunity after vaccination is quite solid and long-lasting.

Nutritional status: Malnutrition increases risk. Measles becomes more severe in the case of malnourished children and the mortality is around 400 times higher than in healthy children. It is due to poor cell-mediated immunity due to malnutrition. Measles precipitates even children into malnutrition.

Sex: Equal in both the sexes.

Environmental factors: It is more common during winter and early spring (Jan to April) due to overcrowding indoors. Poor housing, overcrowding favor disease transmission.

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