Viral Exanthemas

Question 1

What is a “exanthem”?

Answer 1

An “exanthem” is an eruptive widespread rash.

Question 2

What are the 6 viral exanthemas?

Answer 2

Originally there were six “viral exanthemas” known as first, second, third, fourth, fifth and sixth disease. These have since been renamed as we have learned more about their underlying causes:

• First disease: measles
• Second disease: scarlet Fever
• Third disease: rubella (German measles)
• Fourth disease: Dukes’ Disease
• Fifth disease: parvovirus B19
• Sixth disease: roseola Infantum

Question 3

What causes measles?

Answer 3

Measles is caused by the measles virus.

Question 4

How is measles spread?

Answer 4

It is highly contagious via respiratory droplets.

Question 5

How does measles present?

Answer 5

Symptoms start 10 – 12 days after exposure, with fever, coryzal symptoms and conjunctivitis.

Koplik spots are greyish white spots on the buccal mucosa. They appear 2 days after the fever. They are pathognomonic for measles, meaning if a patient has Koplik spots, you can diagnose measles.

The rash starts on the face, classically behind the ears, 3 – 5 days after the fever. It then spreads to the rest of the body. The rash is an erythematous, macular rash with flat lesio

Question 6

Briefly describe the management of measles

Answer 6

Measles is self resolving after 7-10 days of symptoms.

Question 7

How long should children remain off school for with measles?

Answer 7

Children should be isolated until 4 days after their symptoms resolve.

Question 8

Is measles a notifiable disease?

Answer 8

Measles is a notifiable disease and all cases need to be reported to public health.

Question 9

What % of patients with measles develop complications?

Answer 9

30% of patients with measles develop a complication.

Question 10

What are the complications of measles?

Answer 10

Complications include:

• Pneumonia
• Diarrhoea
• Dehydration
• Encephalitis
• Meningitis
• Hearing loss
• Vision loss
• Death

Question 11

What causes Scarlet fever?

Answer 11

Scarlet fever is associated with group A streptococcus infection, usually tonsillitis. It is not caused by a virus.

Scarlet fever is caused by an exotoxin produced by the streptococcus pyogenes (group A strep) bacteria.

Question 12

How does Scarlet fever present?

Answer 12

It is characterised by a red-pink, blotchy, macular rash with rough “sandpaper” skin that starts on the trunk and spreads outwards. Patients can have red, flushed cheeks.

Other features:

• Fever
• Lethargy
• Flushed face
• Sore throat
• Strawberry tongue
• Cervical lymphadenopathy

Question 13

Briefly describe the management of Scarlet fever

Answer 13

Treatment is with antibiotics for the underlying streptococcal bacterial infection. This is with phenoxymethylpenicillin (penicillin V) for 10 days.

Question 14

Is Scarlet fever a notifiable disease?

Answer 14

Scarlet fever is a notifiable disease and all cases need to be reported to public health.

Question 15

How long should children with Scarlet fever remain off school?

Answer 15

Children should be kept off school until 24 hours after starting antibiotics.

Question 16

What other conditions is associated with group A strep infection?

Answer 16

Patients can have other conditions associated with group A strep infection:

• Post-streptococcal glomerulonephritis
• Acute rheumatic fever

Question 17

What causes rubella?

Answer 17

Rubella is caused by the rubella virus.

Question 18

How is rubella spread?

Answer 18

It is highly contagious and spread by respiratory droplets.

Question 19

How does rubella present?

Answer 19

Symptoms start 2 weeks after exposure.

It presents with a milder erythematous macular rash compared with measles. The rash starts on the face and spreads to the rest of the body. The rash classically lasts 3 days. It can be associated with a mild fever, joint pain and a sore throat. Patients often have enlarged lymph nodes (lymphadenopathy) behind the ears and at the back of the neck.

Question 20

Briefly describe the management of rubella

Answer 20

Management is supportive and the condition is self limiting.

Question 21

Is rubella a notifiable disease?

Answer 21

Rubella is a notifiable disease and all cases need to be reported to public health.

Question 22

How long should children remain off school for with rubella?

Answer 22

Children should stay off school for at least 5 days after the rash appears.

Question 23

Which group of people do children with rubella need to avoid?

Answer 23

Children should avoid pregnant women.

Question 24

What are the complications of rubella?

Answer 24

Complications are rare but include thrombocytopenia and encephalitis.

Question 25

What is the significance of rubella infection in pregnancy?

Answer 25

Rubella is dangerous in pregnancy and can lead to congenital rubella syndrome, which is a triad of deafness, blindness and congenital heart disease.

Question 26

Briefly describe Duke’s disease

Answer 26

Duke’s disease, also known as fourth disease, has very interestingly been mostly forgotten and is never used in clinical practice. Even when it was first described as a similar disease to rubella, there was disagreement about whether it actually existed or whether doctors were simply misdiagnosing a different illness. Since viral and bacterial testing has become possible, no organism has been found that could explain a specific “fourth disease”.

It is very common for children to get non-specific “viral rashes”. It is likely that “fourth disease” was used to describe these non-specific viral rashes that are now understood to be caused by many potential viruses.

Question 27

What disease does infection with parvovirus B19 cause?

Answer 27

Parvovirus B19 is also known as fifth disease, slapped cheek syndrome and erythema infectiosum

Question 28

How does parvovirus B19 present?

Answer 28

Parvovirus infection starts with mild fever, coryza and non-specific viral symptoms such as muscle aches and lethargy. After 2-5 days the rash appears quite rapidly as a diffuse bright red rash on both cheeks, as though they have “slapped cheeks”. A few days later a reticular mildly erythematous rash affecting the trunk and limbs appears that can be raised and itchy. Reticular means net-like.

Question 29

Briefly describe the management of parvovirus B19

Answer 29

The illness is self limiting and the rash and symptoms usually fade over 1-2 weeks. Healthy children and adults have a low risk of any complications and are managed supportively with plenty of fluids and simple analgesia.

Question 30

How long should children remain off school for with rubella?

Answer 30

It is infectious prior to the rash forming, but once the rash has formed they are no longer infectious and do not need to stay off school.

Question 31

Which group of people are at high risk of complications due to parvovirus B19 infection?

Answer 31

Patients that are at risk of complications include immunocompromised patients, pregnant women and patients with haematological conditions such as sickle cell anaemia, thalassaemia, hereditary spherocytosis and haemolytic anaemia. These patients require serology testing for parvovirus to confirm the diagnosis and checking of the full blood count and reticulocyte count for aplastic anaemia. People that would be at risk of complications that have come in contact with someone with parvovirus prior to the rash forming, should be informed and may need investigations.

Question 32

What are the complications of parvovirus B19 infection?

Answer 32

Complications:

• Aplastic anaemia
• Encephalitis or meningitis
• Pregnancy complications including fetal death
• Rarely hepatitis, myocarditis or nephritis

Question 33

What causes roseola infantum?

Answer 33

Roseola infantum is also known as just roseola or sixth disease.

This is caused by human herpesvirus 6 (HHV-6) and less frequently by human herpesvirus 7 (HHV-7).

Question 34

How does roseola infantum present?

Answer 34

Roseola has a typical pattern of illness. It presents 1-2 weeks after infection with a high fever (up to 40ºC) that comes on suddenly, lasts for 3-5 days and then disappears suddenly. There may be coryzal symptoms, sore throat and swollen lymph nodes during the illness. When the fever settles, the rash appears for 1-2 days. The rash consists of a mild erythematous macular rash across the arms, legs, trunk and face and is not itchy.

Question 35

How long should children remain off school for with roseola infantum?

Answer 35

Children make a full recovery within a week and do not generally need to be kept off nursery if they are well enough to attend.

Question 36

What are the complications of roseola infantum?

Answer 36

The main complication to be aware of is febrile convulsions due to high temperature. Immunocompromised patients may be at risk of rare complications such as myocarditis, thrombocytopenia and Guillain-Barre syndrome.