When your baby is sick for the very first time and has a fever, many parents feel deeply worried. Often, the so-called 3-day fever is the first childhood illness your little explorer catches. Since it usually runs a harmless course, concerns are generally unfounded. But how can you tell whether it really is 3-day fever and not another infection? You can find this and more information about the viral illness in our article.

How is the 3-day fever transmitted?

The 3-day fever (medical Exanthema subitum or Roseola infantum ) is a highly contagious, but largely harmless viral disease . The pathogen is a human herpesvirus (HHV-6 or HHV-7), which is transmitted via a droplet infection — for example through sneezing, speaking, or coughing. Since about 80 to 90 percent of the population carries the virus, it is also possible that you transmit it to your child yourself, for example when you kiss them. Most babies and young children develop three-day fever between the sixth and 15th month of life.

What symptoms indicate roseola (exanthem subitum)?

The incubation period after infection with 3-day fever is between seven and 17 days . Then a sudden fever sets in, which can rise above 40 degrees Celsius and last for three to four days before dropping sharply again. Other symptoms that your little explorer may experience include vomiting, diarrhea , an inflamed throat, swollen lymph nodes or eyelids, and a runny nose or cough.

In infants infected with 3-day fever, the often also bulges the out fontanelle forward and becomes tense. After the fever, it may be that within a few hours a small-area, red skin rash spreads across your child’s body. This usually lasts for two to three days before it disappears again. In some children, it does not occur at all. Overall, 3-day fever generally progresses quite harmlessly . Many children have no symptoms at all or only mild symptoms, so in many cases the infection even progresses unnoticed .

Febrile seizures as a complication

Even though most children recover from 3-day fever without any problems, some complications may occur in certain cases. Up to a quarter of young patients experience febrile seizures during 3-day fever. The child temporarily loses consciousness and jerks their arms and legs. It can be quite frightening to see such a convulsion in your child, as it closely resembles an epileptic seizure. But don’t worry: febrile seizures are harmless and leave no lasting damage. If your little explorer has an acute seizure, you can pick them up and make sure they have fresh air so they can breathe freely. The febrile seizure usually passes after a few minutes. If this is the first febrile seizure your baby has experienced, you should consult your pediatrician to rule out other causes besides 3-day fever. In very rare cases, especially in older or immunocompromised children, pneumonia can occur as a result of 3-day fever, and even more rarely, inflammation of the brain, liver, or bone marrow.

How is the 3-day fever treated?

Due to the diffuse symptoms, an exact diagnosis is difficult. Only after the fever subsides and the characteristic rash appears can the pediatrician definitively determine whether your child has actually contracted 3-day fever. If an earlier diagnosis is necessary, for example in immunocompromised children or in cases of very severe illness, the virus can also be detected in the blood, saliva, or cerebrospinal fluid. Because of the sometimes high fever, some children appear seriously ill, and many parents initially suspect other illnesses.

If your baby is under three months old, you should definitely see a doctor if they have a fever. Contact your pediatrician or go to the children’s hospital to rule out other serious causes. If your child is older than three months , a doctor’s visit is not necessarily needed immediately, but it is advisable within the next few hours. However, even with a clear diagnosis, 3-day fever cannot be treated directly; you can only alleviate your little explorer's symptoms :

• Make sure your child drinks enough to compensate for the fluid loss caused by the fever. If they do not want to drink, you should contact your doctor immediately. If your child has little appetite and eats only a small amount for several days but drinks enough, this is not a cause for concern at first.

• You should avoid contact with other children due to the risk of infection. Instead, at home, it’s time for bed rest for your little explorer.

• Home remedies such as lukewarm calf compresses can reduce the fever. However, medications with fever-reducing effects should only be given after consulting your doctor.

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How often can my child get the 3-day fever?

There is no vaccine against 3-day fever, and since the infection is highly contagious, it is difficult to protect against it. By the end of their second year of life, approximately 95 percent of all children have had 3-day fever – sometimes without anyone noticing. The good news: once the illness is over, your little darling is immune to it for a lifetime .

High fever and an unexplained skin rash—many parents are initially shocked when their usually healthy baby suddenly shows these symptoms. But the name says it all: 3-day fever fortunately disappears just as quickly as it came and usually passes without further complications. We hope your child recovers well from the infection and that you can soon turn your attention to more pleasant things!