Roseola infantum or Sixth disease

Who infect the children with Roseola?

Contracting herpes 6 or 7 is usually a result of contact with secretions from the upper respiratory tract of an asymptomatic adult or child.

What is a primary infection, and what happens after the primary infection ends?

In viruses from the herpes family we differentiate between a primary and non-primary infections. A primary infection is when the child first contracts this virus.

All the viruses from the herpes family (herpes 6+7 included), will remain in our body after the primary infection in a latent form. There are a few cases every year when those viruses will “wake up” and cause a recurrent infection called non-primary infection. Usually, in people with good immune systems, these “wake-ups” will be asymptomatic.

What are the clinical signs of Roseola infantum?

It’s important to understand that primary infection with herpes 6 or 7 has a number of clinical presentations. Only one of those, and the most common one, is the classic Roseola infantum, and it occurs in about 20% of children with primary infection with herpes 6.

Classic Roseola is a disease of infants around one year old, presenting with restlessness and high fever for 3-5 days. Most of the time, around the third or fourth day the fever breaks (this is called a “crisis”) or lowers gradually (this is called “lysis”), and then a typical rash appears. The rash is pink, not itchy, starts in the area behind the ears and then spreads to the back, face and extremities. It can be visible for a few hours and up to 3 days intermittently.

Though it’s difficult to diagnose Roseola before the fever breaks and the rash starts, the experienced doctor will find clues in the physical examination, even in the first few days of the disease: moderate erythema in the pharynx, Nagayama spots (rare finding) and enlargement of lymph nodes in the posterior neck region.

We should remember that most babies with primary infection with herpes 6 or 7 will not have the classic presentation of Roseola, and that this virus has other presentations:

• High fever without a source: typically the fever in Roseola is around 40⁰.
• Restlessness: another clue for this infection. Children may present with extreme restlessness, which is often disproportional to the fever. It is interesting to know, that sometimes the restlessness is even worse on the day the fever breaks and the rash starts. In those situations, the restlessness usually persists for another 24 hours.
• Runny nose and cough: possibly.
• Redness around the ear drum: very common. The source for the infection is the viral infection, not a bacterial otitis media (which is a totally different disease, read more here).

Unfortunately, many reasons cause children with Roseola infantum to receive an antibiotic course without any need. The reasons are diverse – from a high fever without a source which makes everyone nervous (parents and doctors alike), and up to redness in the ear canal, mistakenly identified as acute otitis media or redness in the pharynx being identified as bacterial pharyngitis (which as you know – does not exists in this age group).

Moreover, sometimes after starting antibiotics the fever breaks, and everybody think it’s the magic of antibiotics. When in fact, if the child started the antibiotics on the third day of fever, the fever will break on the fourth day – regardless of initiating treatment. Another common mistake is to attribute the rash that appeared after starting antibiotics and after the fever broke, to a drug allergy.

To make a long story short – those who travels the wrong path, arrives to the wrong location.

Because of the high fever (often without a source in physical examination), many of these children arrive to the emergency department more than once in the disease course. One study even found that about fifth of the children aged 6-12 months who arrives to the ER due to fever, suffers from a primary infection with herpes 6.