Measles is a highly contagious viral illness recognized by its distinctive skin rash. Early identification of measles is important due to its rapid spread. Understanding the progression of symptoms and the appearance of the rash can help in recognizing this infection.
Initial Symptoms Before the Rash
Measles begins with a prodromal phase, featuring general symptoms before the rash. Initial signs include a high fever, which can exceed 104°F (40°C) and lasts for several days. A persistent dry cough, a runny nose (coryza), and red, watery eyes (conjunctivitis) are common. These symptoms develop 7 to 14 days after exposure to the virus.
Koplik spots, a unique indicator of measles, appear inside the mouth one to two days before the skin rash. These small, white or bluish-white spots resemble grains of salt on a red background. They are found on the buccal mucosa, the inner lining of the cheeks, often opposite the molars. Koplik spots are a diagnostic clue for early detection, though they may fade as the main rash develops.
The Characteristic Measles Rash
The measles rash emerges three to five days after initial symptoms begin. It is a maculopapular rash, consisting of flat, red spots and some slightly raised bumps. On lighter skin, the rash appears reddish-brown; on darker skin, it can look purple or be harder to discern.
The rash starts on the face, appearing along the hairline, behind the ears, and on the neck. Over the next two to three days, it spreads downwards across the body. This progression covers the trunk, arms, and legs, eventually reaching the palms and soles. As the rash progresses, individual spots may merge, forming larger, blotchy patches.
After peaking, the rash begins to fade in the same order it appeared, starting from the face and moving downwards. This fading process takes about five to seven days. As it resolves, the rash may leave a brownish discoloration on the skin, and fine, flaky peeling can occur. While not usually itchy, some individuals may experience mild itching.
How Measles Differs from Other Rashes
Distinguishing measles from other common childhood rashes involves visual and symptomatic differences. Rubella, also known as German measles, presents with a rash lighter in color and less confluent than measles. The rubella rash fades more quickly and is not accompanied by the severe cough or pronounced conjunctivitis characteristic of measles.
Roseola, or Sixth Disease, also causes a maculopapular rash, but its appearance is pink-red, differing from measles’ red-brown hue. A primary distinction is that the roseola rash appears after a high fever abruptly breaks, whereas the measles rash emerges while the fever is still present or peaking. The roseola rash starts on the torso and spreads outwards, unlike measles, which begins on the face and spreads downwards.
Chickenpox, caused by a different virus, produces a rash composed of itchy, fluid-filled blisters. These blisters eventually crust over, which is visually distinct from the flat or slightly raised spots of measles. Unlike the uniform progression of a measles rash, chickenpox lesions appear in different stages simultaneously across the body.