Episode 190: Measles Basics

Future Dr. Kapur explained the basics of measles, including the pathophysiology, diagnosis and management of this disease. Dr. Schlaerth added information about SPPE and told interesting stories of measles. Dr. Arreaza explained some statistics and histed the episode.  

Written by Ashna Kapur MS4 Ross University School of Medicine. Comments by Katherine Schlaerth, MD, and Hector Arreaza, MD.

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Introduction.

According to the CDC, as of April 24, 2025, a total of 884 confirmed measles cases were reported by 30 states, including California, and notably Texas. This is already three times more cases than 2024. There are 3 confirmed deaths so far in the US. What is measles?

Measles is a disease that’s been around for centuries, nearly eradicated, yet still lingers in parts of the world due to declining vaccination rates. Let's refresh our knowledge about its epidemiology, clinical features, diagnosis, management, and most importantly — prevention.

Definition.

Measles, also known as rubeola, is an acute viral respiratory illness caused by the measles virus. It’s a single-stranded, negative-sense RNA virus belonging to the Paramyxoviridae family. It’s extremely contagious with a transmission rate of up to 90% among non-immune individuals when exposed to an infected person.

Epidemiology

Before the introduction of the measles vaccine in 1963, nearly every child got measles by the time they were 15 years old. With the introduction of vaccination, cases and deaths caused by measles significantly declined. For example, in 2018, over 140,000 deaths were reported in the whole world, mostly among children under the age of 5.

Measles is still a common disease in many countries, including in Europe, the Middle East, Asia, and Africa. Measles outbreaks have been reported recently in the UK, Israel, India, Thailand, Vietnam, Japan, Ukraine, the Philippines, and more recently in the US. So, let’s take prevention seriously to avoid the spread of this disease here at home and abroad. How do we get measles, Ashna?

Mode of Transmission:

● Air: Spread primarily through respiratory droplets.

● Surfaces: The virus remains viable on surfaces or in the air for up to 2 hours. (so, if a person with measles was in a room and you enter the same room within 2 hours, you may still get measles)

● Other people: Patients are contagious from 4 days before until 4 days after the rash appears.

Pathophysiology

The measles virus first infects the respiratory epithelium, replicates, and then disseminates to the lymphatic system.

It leads to transient but profound immunosuppression, which is why secondary infections are common. It affects the skin, respiratory tract, and sometimes the brain, leading to complications like pneumonia or encephalitis.

Clinical Presentation

The classic presentation of measles can be remembered in three C’s:

● Cough

● Coryza (runny nose)

● Conjunctivitis

Course of Disease (3 Phases):

1. Prodromal Phase (2-4 days)

○ High fever (can peak at 104°F or 40°C)

○ The 3 C’s

○ Koplik spots: Small white lesions on the buccal mucosa.

2. Exanthem Phase

○ Maculopapular rash begins on the face (especially around the hairline), then spreads from head to toe. The rash typically combines into 1 big mass as it spreads, and the fever often persists during the rash.

3. Recovery Phase

○ Rash fades in the same order it appeared.

○ Patients remain at risk for complications during and after rash resolution.

Complications:

● Pneumonia (most common cause of death in children)

● Otitis media (most common overall complication)

● Encephalitis (can lead to permanent neurologic sequelae)

● Subacute sclerosing panencephalitis (SSPE): A rare, fatal, degenerative CNS disease that can occur years after measles infection.

High-risk groups for severe disease include:

● Infants and young children

● Pregnant women

● Immunocompromised individuals

Diagnosis

Clinical diagnosis is sufficient if classic symptoms are present, especially in outbreak settings.

Ashna: Laboratory confirmation:

● Measles-specific IgM antibodies detected by serology.

● RT-PCR from nasopharyngeal, throat, or urine samples.

Notify public health authorities immediately upon suspicion or diagnosis of measles to limit spread. 

Management

There is no specific antiviral treatment for measles. Management is supportive:

● Hydration (by mouth and only IV in case of severe dehydration)

● Antipyretics (e.g., acetaminophen) for fever

● Oxygen if hypoxic

Vitamin A supplementation:

● Recommended for all children with acute measles, particularly in areas with high vitamin A deficiency. It has shown to reduce morbidity and mortality.

Hospitalization may be necessary for:

● Severe respiratory compromise

● Dehydration

● Neurologic complications

Prevention: We live in perilous times and vaccination is under scrutiny right now. Before the measles vaccine, about 48,000 people were hospitalized and 400–500 people died in the United States every year. Measles was declared eradicated in the US in 2000, but the vaccination coverage is no longer 95%. How do we prevent measles?

Vaccination is the cornerstone of prevention.

● MMR vaccine (Measles, Mumps, Rubella):

○ First dose at 12-15 months of age.

○ Second dose at 4-6 years of age.

○ 97% effective after 2 doses.

The Advisory Committee on Immunization Practices (ACIP) has noted that febrile seizures typically occur 7 to 12 days after vaccination with MMR, with an estimated incidence of 3.3 to 8.7 per 10,000 doses. The Centers for Disease Control and Prevention (CDC) states that febrile seizures following MMR vaccination are rare and not associated with any long-term effects. The risk of febrile seizures is higher when the MMR vaccine is administered as part of the combined MMRV (measles, mumps, rubella, and varicella) vaccine compared to the MMR vaccine alone.

Post-exposure prophylaxis:

● MMR vaccine within 72 hours of exposure (if possible).

● Immunoglobulin within 6 days for high-risk individuals (e.g., infants, pregnant women, immunocompromised).

Herd immunity requires at least 95% vaccination coverage to prevent outbreaks.

Key Takeaways

● Measles is a highly contagious viral illness that can lead to severe complications.

● Diagnosis is often clinical, but lab confirmation helps with public health tracking.

● Treatment is mainly supportive, with Vitamin A playing a critical role in reducing complications.

● Vaccination remains the most effective tool to eliminate measles worldwide.

While measles might seem like a disease of the past, it can make a dangerous comeback without continued vigilance and vaccination efforts.

Even without trying, every night you go to bed a little wiser. Thanks for listening to Rio Bravo qWeek Podcast. We want to hear from you, send us an email at [email protected], or visit our website riobravofmrp.org/qweek. See you next week! 

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References:

1. Centers for Disease Control and Prevention (CDC). Measles (Rubeola), Clinical Overview, July 15, 2024. Accessed on May 1, 2025. https://www.cdc.gov/measles/hcp/clinical-overview/index.html.
2. World Health Organization (WHO). Measles, November 14, 2024. https://www.who.int/news-room/fact-sheets/detail/measles
3. Gans, Hayley and Yvonne A. Maldonado, Measles: Clinical manifestations, diagnosis, treatment, and prevention, UpToDate, January 15, 2025. Accessed on May 1, 2025. https://www.uptodate.com/contents/measles-clinical-manifestations-diagnosis-treatment-and-prevention
4. Theme song, Works All The Time by Dominik Schwarzer, YouTube ID: CUBDNERZU8HXUHBS, purchased from https://www.premiumbeat.com/.