Measles

Measles, Rubeola

Epidemiology

Measles (rubeola) in the US was declared 'eliminated' in 2000, and was reported at low levels in the US from 2000-2013 with 37-220 cases per year in sporadic outbreaks. Waning vaccination rates have led to an increase in measles in recent years.

2025 outbreak: Texas reports 561 cases, 58 hospitalizations and 2 deaths as of April 15, 2025 (see https://www.dshs.texas.gov/news-alerts/measles-outbreak-2025). As of April 3, 2025, CDC reports a total of 607 confirmed measles cases reported by 22 jurisdictions: Alaska, California, Colorado, Florida, Georgia, Kansas, Kentucky, Maryland, Michigan, Minnesota, New Jersey, New Mexico, New York City, New York State, Ohio, Oklahoma, Pennsylvania, Rhode Island, Tennessee, Texas, Vermont, and Washington.
Previously, 2014 was the worst year in decades with 660 cases in 23 outbreaks. However, in 2019, an extensive outbreak of measles occurred in the US, affecting > 700 individuals in 22 states from Jan - late April (MMWR ePub: 29 April 2019).
Before the advent of efficacious vaccines, measles was a leading cause of death among children. In 1963, with a US population roughly 40% of today’s population, measles led to and estimated 48,000 hospitalizations, 1000 cases of encephalitis, and 400-500 deaths.
Many younger clinicians have never seen or cared for a patient with measles.

Measles is spread by the aerosol route with an R0 of 12-15, making it perhaps the most infectious disease known, with attack rates up to 90% in unvaccinated persons.
The measles virus can linger in the air for up to 2 hours after a contagious patient has left a room, such as a waiting room.
Patients are infectious from the onset of the prodrome until 4 days after the appearance of the rash.
Mortality 1/1000; 1/1000 will get encephalitis. Subacute sclerosing panencephalitis (SSPE) is a rare but fatal complication (Clin Infect Dis 2017; 65: 226).
High risk of complications in children age < 5yrs, Adults >20 yrs, pregnant women, immunocompromised hosts (See Clinical Manifestations, below).
Measles in transplant recipients has high risk of encephalitis (Clin Infect Dis, July 31, 2013).

Measles is a serious illness. It usually follows a predictable course. After an incubation period of 8-10 days prodromal symptoms appear.
- Fever (often high).
- Cough, non-purulent conjunctivitis, coryza (runny nose) - the “3-Cs”.
- Koplik spots (small white papules on the buccal mucosa) may be present. See image below.

Koplik-spots

- Rash appears 3-4 days after the fever, first on the face, usually at the hair line or behind the ears. It spreads to the trunk then extremities.
- The rash is polymorphic, usually a mix of macules and papules. They may feel slightly rough. Rashes may be harder to recognize on darker skin.

- Complications are common. About 20% require hospitalization. Complications include otitis media (7-9%), keratitis, croup, diarrhea (8%), and pneumonia (1-6%). Secondary bacterial pneumonia may occur.
- Neurologic complications include early encephalitis (often with features of ADEM) (~1-3/1000), measles inclusion body encephalitis, usually presenting with one year of infection and subacute sclerosing panencephalitis, a rare fatal complication presenting 7-10 years after infection
- Overall mortality is ~1/1000 in otherwise healthy populations
- Children age <5 yrs, pregnant patients, and immunocompromised patients are at increased risk of complications and death
- Measles leads to depletion of memory T and B cells leading to “immune amnesia,”

Initial management should be based on clinical diagnosis since serology and PCR testing do not come back in a timely manner.
- Measles IgM Serum: Positive a few days after rash onset. False negatives early on and false positives at low titer can occur
- Measles PCR of oropharyngeal of nasopharyngeal secretions: Sensitive but readily available (usually goes through public health departments). Urine PCR may be positive

No antivirals are proven to be effective.
Ribavirin has been used for some immunocompromised patients with severe pneumonitis or encephalitis
Prevention is key. See Prevention below.

Includes hydration, pain control, corneal lubrication for eye irritation, respiratory support, and remaining alert to possible secondary bacterial infection

See Measles Mumps Rubella, Vaccines for indications, available products, dosing, and vaccine characteristics for pre-exposure prevention.
- One dose of the measles vaccine (available as MMR) is 93% effective at preventing measles
- Two doses are 97% effective
- Measles is very rare in a fully vaccinated person, but can occur
- Vitamin A has not been shown to prevent measles but may decrease complications in children with measles (see Management)
- Providers should wear N-95 masks around patients and patients should be placed in negative pressure isolation
Vaccination schedules, adult, child age 7-18 years, child age 0-6 years. (N Engl J Med 2019; 381: 349)
Post-exposure prophylaxis (PEP). Non-immure normal hosts or HIV with CD4 >200 aged ≥ 12 months: MMR vaccine is preferable to IG. Administer within 72 hours of exposure.
- Alternative prophylaxis is intramuscular Immunoglobulin IMIG 0.5 mL/Kg, which can be given up to 6 days after exposure. If IG given will still need later MMR in 3-6 months.
  - Severely immunocompromised persons (including HIV with CD4 <200): Give IGIV (400 mg/kg) within 6 days of exposure regardless of immunological or vaccination status.
  - Pregnant women without evidence of measles immunity: Give IGIV; 400 mg/kg.
- Indications for vaccination or use of extra doses during outbreak situations.