Dermatology
Question 247 of 300
A 5 year old boy is brought into ED with a rash that has developed over the last 24 hours. The child did not receive childhood immunisations due to his parent’s fear of harmful effects. The rash started behind his ears and extended to his face and neck before spreading over his trunk and extremities. On examination you note cervical lymphadenopathy and petechiae on the soft palate. What is the diagnosis?
Answer:
When present, clinical features develop 2–3 weeks after exposure and include:- Rash — present in 50-80% of cases and typically starts on the face and neck before spreading down the body and becoming generalised. The rash is pink or light red, maculopapular and is transient (usually present for 3–5 days).
- Lymphadenopathy — may precede the rash and last for 2 weeks after the rash resolves. The suboccipital (lower part of the back of the skull), postauricular (behind the ears), and cervical (neck) lymph nodes are most often affected.
- Arthritis and arthralgia — arthralgia or arthritis is more common in adults and may occur in up to 70% of women with rubella.
- Forchheimer spots are a fleeting enanthem seen as small, red spots (petechiae) on the soft palate in 20% of patients with rubella.
- Non-specific symptoms tend to tend to affect adults more than children and in adults are sometimes prodromal — symptoms are significantly less severe than those associated with measles. They include low-grade fever (<39°C), headache, malaise, nausea, mild upper respiratory tract symptoms and non-purulent conjunctivitis.
Rubella
Dermatology
Last Updated: 12th February 2021
Rubella (also known as German measles) is a viral infection by a single‐stranded ribonucleic acid (RNA) virus in the family Togaviridae. Once infected or immunised, most people develop life-long immunity to rubella. On rare occasions reinfection can occur, but the clinical significance of this is not clear. Since the measles mumps rubella (MMR) vaccine was introduced, rubella infection has become uncommon in the UK.
Transmission
Transmission occurs through direct contact with an infected person or droplet spread from nasopharyngeal secretions. The virus replicates in the respiratory mucosa and local lymph nodes and is then spread haematologically to the rest of the body (including the placenta and fetus in pregnant women). Following exposure to the rubella virus, susceptible people will develop disease 12–23 days later — rubella is most infectious when the rash is erupting, but people with rubella can be contagious from up to 7 days before to 5-7 days after the rash appears.
Clinical features
There are no clinical features specific to rubella infection — diagnosis cannot be made on clinical features alone, laboratory confirmation is required.
When present, clinical features develop 2–3 weeks after exposure and include:
- Rash — present in 50-80% of cases and typically starts on the face and neck before spreading down the body and becoming generalised. The rash is pink or light red, maculopapular and is transient (usually present for 3–5 days).
- Lymphadenopathy — may precede the rash and last for 2 weeks after the rash resolves. The suboccipital (lower part of the back of the skull), postauricular (behind the ears), and cervical (neck) lymph nodes are most often affected.
- Arthritis and arthralgia — arthralgia or arthritis is more common in adults and may occur in up to 70% of women with rubella.
- Forchheimer spots are a fleeting enanthem seen as small, red spots (petechiae) on the soft palate in 20% of patients with rubella.
- Non-specific symptoms tend to tend to affect adults more than children and in adults are sometimes prodromal — symptoms are significantly less severe than those associated with measles. They include low-grade fever (<39°C), headache, malaise, nausea, mild upper respiratory tract symptoms and non-purulent conjunctivitis.
Differential diagnosis
Other conditions which can present with similar clinical features to rubella include:
- Parvovirus B19
- Parvovirus B19 is the virus that causes erythema infectiosum (also known as fifth disease or slapped cheek syndrome, particularly common in children). It is a self-limiting illness which, in addition to a bright red rash on the cheeks, may cause a red, lacy rash on the rest of the body. In adults, parvovirus can cause rash, fever, and joint inflammation that can be indistinguishable from rubella. Parvovirus B19 can have harmful effects on the fetus, and pregnant women with a rubella-like rash are usually also tested for parvovirus B19 infection.
- Measles
- Measles causes a characteristic erythematous and maculopapular rash with a similar distribution to rubella. However, both the rash and accompanying symptoms of viremia (malaise, fever, loss of appetite, cough, rhinorrhoea, and conjunctivitis) tend to be more severe than in rubella, particularly in children.
- Other viral infections including:
- Herpesvirus type 6 (roseola infantum), enterovirus, adenovirus, cytomegalovirus, HIV, hepatitis, echovirus, coxsackievirus.
- Tropical viruses including alphaviruses and flaviviruses (for example Dengue fever, West Nile virus, Dengue virus, Chikungunya virus, and Zika virus) — consider tropical viruses if the person has recently travelled to an endemic area.
- Other infections including:
- Scarlet fever.
Brucellosis, Kawasaki disease, syphilis, and toxoplasmosis.
Drug reactions for example mononucleosis reaction with amoxicillin and reaction to anti-epileptic drugs.
- Scarlet fever.
Management
- Contact the local Health Protection Team (HPT) immediately.
- Rubella is a notifiable disease.
- An immediate oral fluid sample may be requested — if positive, further testing may be carried out for confirmatory and genotyping purposes.
- Samples may also be tested for other infections which can present with similar clinical features (such as measles).
- Advise the person:
- That rubella is usually a mild, self-limiting condition which typically resolves within a week.
- That there is no specific treatment for rubella — they should rest, drink adequate fluids, and take paracetamol or ibuprofen for symptomatic relief.
- To stay away from school or work for at least 5 days after the initial development of the rash.
- To avoid contact with pregnant women.
- To minimise the risk of spread of infection to others by simple hygiene measures such as covering their mouth and nose with a disposable tissue and washing their hands after using or disposing of tissues.
Complications
- Rubella can cause serious complications in pregnancy including miscarriage, stillbirth and severe birth defects known as Congenital Rubella Syndrome (CRS).
- If infection occurs early in pregnancy there is a 90% chance of the virus being passed to the fetus. The severity and type of congenital defect likely to develop vary according to the stage of pregnancy when infection occurs — multiple defects are most likely if infection occurs during the first 16 weeks gestation.
- CRS can lead to development of one or more abnormalities including eye defects (such as cataracts), hearing impairment, cardiac abnormalities (such as patent ductus arteriosus and pulmonary artery stenosis), central nervous system defects (such as microencephaly, mental and psychomotor retardation and progressive panencephalitis), intrauterine growth restriction, autism, and endocrine abnormalities (such as diabetes mellitus and thyroid dysfunction).
- Rubella rarely causes complications in otherwise healthy people.
- Arthritis and arthralgia (most commonly in adult women) can occur but is rarely severe or persistent.
- Bleeding disorders (thrombocytopenia) have been reported in about 1 in 3000 infections.
- Encephalitis has been reported in about 1 in 6000 cases — other rarely occurring neurological complications include myelitis, optic neuritis, peripheral neuritis, and Guillain-Barre syndrome.
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
