Organism, Causative Agent, or Etiologic Agent
Measles virus is a paramyxovirus from the genus Morbillivirus.
Measles is a highly contagious virus that lives in the nose and throat mucus of an infected person. When that person sneezes or coughs, droplets spray into the air and can infect people around him. Measles is so contagious that if one person has it, 90% of the people close to that person who are not immune will also become infected with the measles virus. Also, measles virus can live for up to two hours in an airspace where the infected person coughed or sneezed. If other people breath the contaminated air or touch the infected surface, then touch their eyes, noses, or mouths, they can become infected.
Symptoms (Clinical Illness)
A typical case of measles begins with mild to moderate fever, cough, runny nose, red eyes, and sore throat. Two or three days after symptoms begin, tiny white spots (Koplik’s spots) may appear inside the mouth. Three to five days after the start of symptoms, a red or reddish-brown rash appears. The rash usually begins on a person’s face at the hairline and spreads downward to the neck, trunk, arms, legs, and feet. When the rash appears, a person’s fever may spike to more than 104 degrees Fahrenheit.
Ranges for 7-21 days (average of 10-12 days) from exposure to the onset of prodromal symptoms.
Measles is the most communicable during the 3-4 days preceding rash onset. Persons with measles have been known to shed virus between 4 days prior to rash onset and up to 4 days after the rash has appeared.
Prevention and Vaccination
Immunization is the only way to prevent measles. Measles vaccination is required for school entry in Texas.
School Exclusion Policy
Children with suspected or confirmed measles should be kept out of school or childcare until 4 days after the onset of rash. Rules for exclusion of sick children from school and childcare are outlined in the Texas Administrative Code, specifically Rule 97.7 for schools and Rule 746.3603 for childcare.
Recent Texas Trends
Prior to vaccine introduction, annual measles incidence peaked at 85,862 in 1958 in Texas. Since the introduction of vaccine, cases have decreased by 99.9 percent in Texas. Nearly all cases and outbreaks of measles in the US and Texas since 2000 have occurred among persons exposed to imported cases from countries where measles is still endemic. Because measles is still endemic in many parts of the world and is highly contagious, measles can easily be re-introduced into Texas in unvaccinated communities. This was seen in 2013, when a person traveling to Asia returned with the measles and interacted with a vaccine-hesitant community. In a matter of weeks, 20 additional people were infected with measles. Overall in 2013, 27 cases were reported, the highest annual case count in over 20 years. In 2019, Texas experienced an increase of measles to 23 cases, the highest case count since 2013.