2. Fifth Disease
Fifth disease has been called the "slapped cheek" disease because it causes a red rash on the face that looks like a slap mark. A lacy red rash may also appear on the child's torso and limbs. Fifth disease doesn't always make a child feel ill, but it can feel like a cold early on, before the rash shows up.
The cryptic name is a holdover from medical lingo a century ago, when a French physician assigned numbers to the common childhood diseases characterized by rashes. For example, measles was "first disease," scarlet fever was "second disease," and so on.
We now know that fifth disease is caused by a virus called human parvovirus B19. Up to 20% of children may get the virus before age 5, and up to 60% have had it by age 19. Infections are usually not very serious and go away in seven to 10 days. Many children infected with the virus don't show any symptoms. "In most cases, it's a pretty benign situation," Brady says.
However, sometimes infection with parvovirus B19 can lead to new onset of joint pain and be mistaken for rheumatoid arthritis. These joint symptoms usually go away within 3 weeks.
3. Hand, Foot, and Mouth Disease
Hand, foot, and mouth disease is not to be confused with foot-and-mouth disease, which infects only livestock. A common childhood illness, hand, foot, and mouth disease causes a fever with blisters or sores inside the mouth and on the palms and soles of the feet. The blisters may also appear on the buttocks, "but we decided to leave that out of the name," Brady says.
Hand, foot, and mouth disease is caused by a variety of viruses called enteroviruses. In the United States, the disease is usually caused by a virus known as coxsackievirus A16. This virus usually goes around in the summer and early fall.
Hand, foot, and mouth disease may cause a lot of discomfort, but for most children it isn't very serious and goes away on its own after a week to 10 days.
Croup is a childhood illness usually caused by a group of viruses called human parainfluenza viruses, which also cause the common cold. The main symptom of croup is a "barking" cough, sometimes likened to the barking sound a seal makes. Croup can be serious enough to require treatment in a hospital. Up to 6% of children with croup are hospitalized, but it is very rarely fatal. For severe cases, treatment helps to keep the sick child breathing normally until the infection ends. A case of croup typically lasts about one week.
It's estimated that six in 100 children get croup each year. Children who get it tend to be younger than 6 years old, and it's seen most frequently in 2-year-old children.