4. General Malaise
When a person first develops measles, a lot of the symptoms of the disease are easy to confuse with the common cold or even the flu. As mentioned, with each of these illnesses, a person will often run a fever and may develop a cough. The rash is one of the few symptoms that are truly different from a regular cold or the flu. Another symptom that is similar in all three illnesses is a feeling of general malaise.
This includes pains, fatigue, and muscle aches. All of these are prevalent among many different types of viral infections. This is why it can be difficult to diagnose the measles before the rash develops on the skin. Unfortunately, this also means that a person who has measles may not realize it until they have been to many different places such as school or work, thus spreading the illness to many people all at once.