Understanding Measles: What Every Parent Should Know
This is the first article in our three-part series on measles. In this installment, we explore what measles is, how it spreads, and why this highly contagious disease remains a concern for families today.
What Is Measles?
Measles is far more than "just a rash." It's an acute viral disease caused by the measles virus (a member of the Morbillivirus genus in the Paramyxoviridae family). Unlike many other childhood illnesses, measles affects only humans—we are its natural and only host.
Before vaccination became widespread, measles was so common that nearly everyone contracted it during childhood, with more than 90% of people becoming immune by age 15 simply through infection. Today, thanks to vaccination efforts, measles cases have decreased by over 99% in the United States since the vaccine was introduced in 1963.
How Measles Presents: Recognizing the Signs
Measles begins with a prodromal phase (early symptoms) before the characteristic rash appears. Parents should be aware of the classic symptoms that develop in sequence:
Early Signs (Prodromal Phase)
• High fever (often 103°F-105°F)
• The three Cs: Cough, Coryza (runny nose), and Conjunctivitis (red, watery eyes)
• Inside the mouth, tiny white spots with bluish-white centers on a red background (called Koplik spots) may appear 2-3 days before the rash—these spots are pathognomonic, meaning they're unique to measles
The Measles Rash
• Appears 3-5 days after symptoms begin
• Starts at the hairline, then spreads downward to the face, neck, and trunk
• Appears as flat red spots that may become raised and join together
• On lighter skin, the rash appears bright red; on darker skin tones, it may appear as darker patches or have a purple hue
Many parents today have never seen measles, making recognition challenging. This is why any unexplained rash accompanied by high fever warrants medical attention, especially if measles cases have been reported in your community.
How Measles Spreads: Understanding Transmission
Measles is one of the most contagious diseases known to medicine. Consider these facts:
The virus spreads through direct contact with infectious droplets or airborne transmission
When someone with measles coughs or sneezes, the virus can remain suspended in the air for up to two hours
If you're not immune and exposed to measles, you have a 90% chance of becoming infected
A person with measles is contagious from four days before the rash appears until four days after it emerges
The incubation period (time from exposure to first symptoms) averages 11-12 days
The average time from exposure to rash is 14 days, with a range of 7-21 days
This extraordinary level of contagiousness means that to stop ongoing transmission in a community, we need population immunity levels of 92-94% or higher—a concept known as the Community Immunity Threshold.
Beyond the Rash: Complications of Measles
While many children recover from measles without lasting effects, complications can occur and are more common in certain groups:
Common Complications
Ear infections (otitis media) in about 1 in 10 children
Diarrhea in about 8% of cases
Pneumonia in about 5% of cases—this is the most common cause of measles-related deaths
Croup (laryngotracheobronchitis)
Severe Complications
• Acute encephalitis: Inflammation of the brain occurring in approximately 1 in 1,000 cases, often resulting in permanent neurological damage
• Death: In the post-elimination era in the United States, measles has a mortality rate of 1-3 per 1,000 reported cases
High-Risk Groups
Complications are more likely in:
Children under 5 years of age
Adults over 20 years of age
Pregnant women
People with compromised immune systems
Malnourished individuals (including those with vitamin A deficiency)
Long-Term Effects
Recent studies have revealed that measles can cause long-lasting harm to the immune system through what scientists call "immune amnesia." After measles infection, the immune system can "forget" its defenses against other pathogens you've previously encountered, potentially leaving you more vulnerable to other infections for years after recovering from measles.
Rare But Serious Long-Term Complications
Two rare but devastating neurological complications can occur after measles infection:
Measles Inclusion Body Encephalitis (MIBE)
Occurs in immunocompromised individuals
Usually presents within one year of measles infection
Characterized by progressive neurological dysfunction over weeks to months
Subacute Sclerosing Panencephalitis (SSPE)
A rare degenerative central nervous system disease
Typically occurs 7-11 years after wild-type measles infection
Characterized by behavioral changes, intellectual deterioration, and seizures
Highest rates occur in children infected before 2 years of age
Almost always fatal
Diagnosing Measles: How Doctors Confirm Cases
While the clinical presentation of measles can be distinctive, laboratory confirmation is essential, especially since many healthcare providers today have never seen a case. Measles can be confirmed through:
· Detection of measles viral RNA through nucleic acid amplification tests
· Detection of measles virus-specific immunoglobulin M (IgM) in serum
· A fourfold increase in measles IgG antibody concentration between acute and convalescent serum specimens
· Isolation of measles virus in cell culture (though this is less common today)
When measles is suspected, samples should be collected as soon as possible. Healthcare providers typically collect:
• A throat or nasal swab (for viral RNA detection)
• A blood sample (for antibody testing)
In Our Next Installment
In part two of our series, we'll explore the history of measles vaccination, current recommendations, and how vaccines have dramatically changed the landscape of this once-universal childhood disease. We'll also discuss who should—and shouldn't—receive the measles vaccine, and address common questions parents have about vaccination.
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