If your child is exposed to someone with roseola and becomes infected with the virus, it generally takes a week or two for signs and symptoms of infection to appear — if they appear at all. It's possible to become infected with roseola, but have signs and symptoms too mild to be readily noticeable. Roseola symptoms may include:

• Fever. Roseola typically starts with a sudden, high fever — often greater than 103 F (39.4 C). Some children also may have a sore throat, runny nose or cough along with or preceding the fever. Your child may also develop swollen lymph nodes in his or her neck along with the fever. The fever lasts three to five days.
• Rash. Once the fever subsides, a rash typically appears — but not always. The rash consists of many small pink spots or patches. These spots are generally flat, but some may be raised. There may be a white ring around some of the spots. The rash usually starts on the chest, back and abdomen and then spreads to the neck and arms. It may or may not reach the legs and face. The rash, which isn't itchy or uncomfortable, can last from several hours to several days before fading.

Other signs and symptoms of roseola may include:

• Irritability in infants and children
• Mild diarrhea
• Decreased appetite
• Swollen eyelids

The most common cause of roseola is the human herpes virus 6, but the cause also can be another herpes virus — human herpes virus 7.

Like other viral illnesses, such as a common cold, roseola spreads from person to person through contact with an infected person's respiratory secretions or saliva. For example, a healthy child who shares a cup with a child who has roseola could contract the virus.

Roseola is contagious even if no rash is present. That means the condition can spread while an infected child has only a fever, even before it's clear that the child has roseola. Watch for signs of roseola if your child has interacted with another child who has the illness.

Unlike chickenpox and other childhood viral illnesses that spread rapidly, roseola rarely results in a communitywide outbreak. The infection can occur at any time of the year.

Older infants are at greatest risk of acquiring roseola because they haven't had time yet to develop their own antibodies against many viruses. While in the uterus, babies receive antibodies from their mothers that protect them as newborns from contracting infections, such as roseola. But this immunity decreases with time. The most common age for a child to contract roseola is between 6 and 15 months.

Seizures in children

Occasionally a child with roseola experiences a seizure brought on by a rapid rise in body temperature. If this happens, your child might briefly lose consciousness and jerk his or her arms, legs or head for several seconds to minutes. He or she may also lose bladder or bowel control temporarily.

If your child has a seizure, seek emergency care. Although frightening, fever-related seizures in otherwise healthy young children are generally short-lived and are rarely harmful.

Complications from roseola are rare. The vast majority of otherwise healthy children and adults with roseola recover quickly and completely.

Concerns for people with weak immune systems

Roseola is of greater concern in people whose immune systems are compromised, such as those who have recently received a bone marrow or organ transplant. They may contract a new case of roseola — or a previous infection may come back while their immune system is weakened. Because they have less resistance to viruses in general, immune-compromised people tend to develop more-severe cases of infection and have a harder time fighting off illness.

People with weak immune systems who contract roseola may experience potentially serious complications from the infection, such as pneumonia or encephalitis — a potentially life-threatening inflammation of the brain.