Infectious diseases in children: Roseola infantum

Roseola is a common childhood illness involving a rash and a temperature, and although relatively harmless in itself, can be challenging for the healthcare professional because its symptoms could be those of many more serious illnesses that need to be ruled out before a diagnosis is made

Roseola infantum is seen in around a third of all children before they are two. It is an important disease to know about, because it is one of the common causes of red rash, but more importantly because it initially causes a prolonged high fever without rash, which is likely to bring children to the surgery.

THE ORGANISM

Roseola is caused by two herpes viruses (also called roseoloviruses), herpes viruses type 6 and 7 (other herpes viruses include those that cause cold sores, genital herpes, and chickenpox). Studies have shown that over 90% of all children are HV6 positive by the age of 2 years.¹ However, only about a third develop the temperature and rash.

NAMING ROSEOLA

Roseola has had many other names, which perhaps reflects the difficulty in diagnosing it: in the UK it is also known as exanthema subitum (literally Latin for sudden red rash), three day fever, and Sixth disease.

It has historically also been called baby measles. In the Phillippines, it is known as wind measles, in Norway (confusingly) as fourth disease and in mandarin Chinese 'fast rash.'

The name 'sixth disease' originates from a historical list of the most common childhood exanthems (red rashes) prevalent at the turn of the nineteenth century.² It's interesting to note that, then, 'first disease' was measles, 'second disease,' scarlet fever, 'third disease,' rubella and 'fifth disease,' slapped cheek disease. Fourth disease was probably not a disease at all, although it is thought to have referred to spreading staphylococcal infection of the skin (scalded skin syndrome).

WHO GETS ROSEOLA?

Most children who develop the disease do so between 6 months (when maternal antibodies passed through the placenta have worn off) and 15 months.³ As with all common childhood infections, a few escape the net and catch it later, and cases have been reported in 18-year-olds. Unusually for childhood illnesses, however, roseola is not more severe in older children, in whom it tends to cause a 3-day fever and a transient rash.

SYMPTOMS

The fever

Roseola can begin with mild URTI symptoms — coryza, swollen lymph nodes in the neck and sore throat, but usually it starts simply with a fairly sudden high (39.5) fever.^3,4

The fever typically lasts 4 to 7 days before the rash appears, and most parents will at this point seek medical advice. Parents are good at managing short fevers, but if you check the instructions on a bottle of paediatric paracetamol suspension, you will see that parents are advised not to use it for more than two days in a row. Therefore, the practice nurse is highly likely to see the child before the appearance of the rash.

Roseola causes a sudden temperature, and the rapid rise may cause febrile convulsions (Box 1). This virus is one of the commonest precipitants.

Febrile convulsions are frightening to parents — and indeed unless the diagnosis is certain beause of previous experience of febrile convulsion in the same child (together with a suitable history of rising temperature) then children with convulsion and fever need to be reviewed on the paediatrics ward. This is because a differential diagnosis for fever with fitting is, of course, meningitis, or indeed brain infection of any kind.

The rash

The high fever of roseola ends rather suddenly with the appearance of the rash.

This is a light red patchy (non-confluent) blanching rash when seen on white skin, and some patches may have a characteristic tendency to a pale halo around the patches. It is not sore and it doesn't itch. It's usually a flat rash although it can be slightly raised.

On brown skin the rask may be very difficult to detect, causing very slight, patchy darkening.

The rash starts on the trunk and spreads over all of the body, although the face tends to be spared. This is in contrast to measles and rubella, both of which tend to start on the face and move onto the trunk. It's not as confluent as measles or scarlet fever. (Nor are there the associated red eyes and cough of measles, and in measles the temperature remains after the rash appears.). The rash typically lasts 2-3 days days before fading, and the child is usually well at this time, unlike children with measles.

Another differential diagnosis, Kawasaki disease, also causes a prolonged fever classically swinging up and down for 5 days or more. The rash tends to be much more vivid, and is accompanied with conjunctivitis, sore lips and tongue and, later, swollen hands and feet. Children with measles and kawasaki are unwell with their rash. However, clearly there is some overlap in presentation, particularly on non white skinned children.

Occasionally children with roseola may develop nausea and vomiting, or a more obvious URTI. They may seem a bit tired, and occasionally swollen eyelids have been reported

TRANSMISSION

Roseola is very contagious and spreads rapidly in nurseries and playgroups. It's passed by respiratory droplet infection, and as the incubation period is 10—15 days, infected children have plenty of chance to pass it on before developing symptoms and being kept at home. Children are probably infectious throughout the whole illness.^3,4

TREATMENT

There is no specific treatment for roseola other than symptomatc support of the child with a temperature. It is likely that it would respond to antivirals which are effective against CMV, a closely related virus, but as the illness is essentially harmless (apart from the worry of the febrile convulsions, which will occur before diagnosis anyway) treatment would not usually be considered justified.

PREVENTION

There is no vaccine against roseola, and no real need to develop one is perceived, as there are no known complications.

IMMUNOCOMPROMISED PATIENTS AND PREGNANCy

Immunocompromised patients are always at greater risk from any infection. While there are no specific worries in the case of roseola, anyone who is immunocompromised needs medical review when exposed to infectious disease.

Pregnant women are not generally susceptible to roseola, but if they do develop it it is not known to harm the baby, although the baby may be born carrying the virus for a while. It's main significance in pregnancy is that one of the differential diagnoses is german measles (rubella) and this will need to be serologically ruled out before a diagnosis of roseola can be assumed.

DIFFERENTIAL DIAGNOSIS

This is where roseola, an otherwise relatively harmless infcection, causes a lot of difficulty.3—6

There are two issues — differential diagnosis for the rash and differential diagnosis for the temperature.

The differential diagnosis for the rash includes many childhood exanthems, some of which have possible serious or life threatening sequeale, so if unsure of the diagnosis it is important to seek advice.

Differential diagnoses include measles, rubella, Kawasaki disease, slapped cheek disease, scarlet fever. Meningococcal disease is also on the list as it can cause a blanching rather than a non-blanching rash.

What presents the greater difficulty, thought is differential diagnosis of the prolonged temperature prior to appearance of the rash.

ASSESSING FOUR DAY FEVERS

Roseola infantum often presents as fever without apparent source.

So how do you deal with and assess a child with a four day fever? Box 2 gives some idea of what you should look for.

A temperature needs a probable diagnosis, even if the diagnosis is 'probably viral and harmless'. However, most viral temperatures have passed in 48 hours, so 3 days into the roseola infection we can no longer say this with comfort.

Longer lasting temperatures can suggest an infection focus somewhere. You need to find it or enlist someone else to find it, as some serious conditions such as Kawasaki Disease cause prolonged temperatures and may be otherwise difficult to diagnose.

In 20% of children with fever there is no apparent source for a temperature despite a full history and examination. Most of these patients are under 3 years old and they create anxiety both in primary care and in emergency departments.

Box 3 gives a list of situations in which simple reassurance might not be enough, and the child may need paediatric review. This is highly likely to include many early cases of roseola. A list of other possible causes of prolonged temperature is given in Box 4.

PENICILLIN ALLERGY AND ROSEOLA

The fever of roseola generates a search for a focus of infection in the ears throat or urine. Parental expectations, and reddened eardrums associated with the temperature, may persuade the nurse or doctor into a short course of amoxicillin — and then, lo and behold, the rash of roseola appears. Sadly, only too often, a diagnosis of amoxicillin allergy is then made and persists for life!

SUMMARY

Roseola is a common, viral childhood illness. Unfortunately in its early stages it causes a very high temperature, typically in very young children, which lasts very much longer than we find comfortable without a diagnosis.

Children with roseola are not worryingly ill — but nevertheless no child with a high temperature looks or feels great, and you should have a low threshold of asking for review of children with prolonged temperatures.

Clinical diagnosis of roseola can only be made further into the illness when the rash has appeared.

The practuce nurse should keep roseola high on her knowledge list, but not despair if she never manages to diagnose it clinically.

REFERENCES

1. Zerr DM, Meier AS, Selke SS, et al. A Population-Based Study of Primary Human Herpesvirus 6 Infection. New Engl J Med 2005;352(8): 768—776.

2. Bialecki C, Feder HM, Grant-Kels JM. The six classic childhood exanthems: a review and update. J Am Acad Dermatol 1989;21 (5 Pt 1):891—903.

3. Roseola — Mayo Clinic online: accessed 10/7/13: http://www.mayoclinic.com/health/roseola/DS00452

4. Lissauer T, Clayden G. Illustrated textbook of paediatrics. Mosby: London, 1997, pp.36-7.

5. Baker MD. Evaluation and management of infants with fever. Pediatr Clin North Am 1999; 46(6):1061-72.

6. Baraff LJ. Management of fever without source in infants and children. Ann Emerg Med 2000; 36(6):602-14.

7. Rantala R, Uhari M, Hietala J. Factors triggering the first febrile seizure. Acta Paediatr 1995;84(4):407-10.

8. Suga S, Suzuki K, Ihira M et al. Clinical characteristics of febrile convulsions during primary HHV-6 infection. Arch Dis Child 2000; 82(1):62-6.