Rubella | Diagnosis | Pregnancy

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Introduction

Rubella, also known as German measles, is a viral infection transmitted via respiratory droplets. It is a notifiable disease in the United Kingdom.¹

Before the introduction of the MMR (measles, mumps, rubella) vaccine in 1988, rubella was common among children aged 5 to 10, and over 80% of adults showed evidence of past infection.^1-2 Since widespread vaccination, the incidence has dropped significantly. Between 2012 and 2021, fewer than 100 confirmed cases were reported in England and Wales, with no confirmed cases since 2019.³

Globally, rubella remains more prevalent in regions such as Africa, East Asia, and South Asia. In 2019, approximately 49,000 cases were reported worldwide, falling to around 17,000 cases in 2022.⁴

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Aetiology

Rubella is caused by a single-stranded, positive-sense RNA virus from the Matonaviridae family, the only member of the Rubivirus genus.⁵ Transmission occurs through direct contact or droplet spread from nasopharyngeal secretions.

The incubation period ranges from 14 to 21 days, with most developing a rash 14 to 17 days after exposure. Individuals are infectious from 7 days before the appearance of symptoms and until 4 to 10 days after the onset of rash, and are most infectious when the rash is erupting.¹

Immunity acquired by natural infection or vaccination is typically lifelong, although reinfections have been reported after both natural infection and receiving a single dose of the rubella vaccine.⁵

Pathophysiology

Humans are the only known reservoir for rubella.⁵

Figure 1. Pathophysiology of rubella

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Risk factors

Risk factors for rubella include:

• Lack of vaccination or incomplete vaccination
• Travel to endemic areas
• Close contact with infected household members
• Immunodeficiency ⁵

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Clinical features

History

Patients can be asymptomatic in 25-50% of cases, especially young children.

Typical symptoms of rubella begin 1-5 days before the onset of rash and include:

• Low-grade fever (< 39°C)
• Malaise
• Anorexia
• Headache
• Sore throat
• Mild upper respiratory symptoms
• Non-purulent conjunctivitis
• Arthralgia and arthritis

Other important areas to cover in the history include:

• Contact history
• Immunisation status
• Travel history
• Pregnancy status: due to the risk of congenital rubella syndrome
• Immunosuppression

Clinical examination

Typical clinical findings in rubella include:

• Rash/exanthem: pinpoint pink macules and papules which can be scarlatiniform or purpuric. It is usually the first sign in children, starting on the face and neck, spreading to the trunk and limbs, lasting 3 to 4 days and fading in the same order of appearance.
• Lymphadenopathy: presents 5 to 10 days before the rash and can persist for up to 2 weeks after rash resolution. Involvement includes the postauricular, suboccipital nodes and anterior cervical nodes.

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Differential diagnoses

Possible differential diagnoses in the context of suspected rubella include:

• Measles: presents with a fever, cough, coryza, and red eyes, followed by the appearance of Koplik spots inside the mouth and a maculopapular rash that begins on the face and moves down the body
• Parvovirus B19: slapped cheek facial erythema followed by a lacy, reticular rash on limbs. Arthralgia is common in adults.
• Scarlet fever: fever, sore throat, strawberry tongue and a sandpaper-textured rash starting on the trunk
• Kawasaki disease: high fever, widespread rash, bilateral dry conjunctivitis, inflammation of the lips and mouth, and cervical lymphadenopathy
• Roseola infantum (HHV-6): high fever with cold-like symptoms, swollen eyelids and lymphadenopathy lasting 3 to 5 days. Non-itchy rash appears as pink-red spots or patches, starting on the trunk, then spreading, and fades within 2 days.
• Tropical viruses: if there is a history of travel to endemic regions
• Syphilis
• Toxoplasmosis
• Drug reactions such as mononucleosis reaction with certain penicillins ^{1, 6-8}

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Investigations

Rubella cannot be accurately diagnosed solely based on history and clinical features, as the symptoms can be mild and nonspecific. Hence, laboratory confirmation is essential.

Diagnosis of rubella infection

Investigations include:

• Rubella-specific IgM antibodies: the primary diagnostic test, and antibodies are detectable from 4 days after the onset of rash
• Rubella-specific IgG serology: a four-fold or greater rise between acute and convalescent serum samples confirms recent infection or reinfection
• Rubella-specific IgG avidity testing: to differentiate recent primary infection from past exposure

Diagnosis of rubella exposure during pregnancy

In cases where a pregnant woman has been exposed to suspected rubella, a blood sample should be tested for rubella-specific IgG antibodies.

• Positive IgG: indicates immunity; the woman can be reassured
• Negative IgG: suggests susceptibility; repeat testing for both rubella-specific IgG and IgM antibodies after 3 weeks to exclude an asymptomatic primary infection ⁵

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Management

Contact the local health protection team immediately, as rubella is a notifiable disease.

Non-pregnant people

Rubella is usually a mild, self-limiting illness that resolves within a week without complications in most individuals.

Management is supportive and includes:

• Rest and adequate fluid intake
• Paracetamol or ibuprofen for fever and arthralgia
• Aspirin should be avoided in children under 16 years due to the risk of Reye’s syndrome

To reduce the risk of transmission, those with suspected or confirmed rubella should:

• Avoid school or work for at least 5 days after the appearance of the rash
• Avoid contact with pregnant women during the infectious period
• Practice good respiratory hygiene, such as covering the mouth and nose when coughing or sneezing, using disposable tissues and discarding them properly and regular hand washing after handling tissues

Pregnant people

Laboratory testing is essential for all pregnant women with suspected rubella infection, regardless of previous rubella testing, immunisation status or gestational age.

Confirmed infection <20 weeks gestation

Urgent referral to obstetrics/fetal medicine is required for risk assessment, counselling and ongoing management.

In pregnant women exposed to rubella (when termination is not an option), immunoglobulin can be considered within 72 hours of exposure.^{2, 9}

Confirmed infection ≥20 weeks gestation

Reassurance can be provided as there have been no reported cases of congenital rubella syndrome after this point in pregnancy. Treatment remains the same as for non-pregnant people.

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Complications

Non-pregnant people

Complications are rare in healthy individuals with rubella, but may include:

• Arthralgia and arthritis: most commonly affects adult women and can persist for weeks or months, or recur intermittently
• Thrombocytopenia: in approximately 1 in 3,000 cases
• Neurological complications: encephalitis occurs in around 1 in 5,000 cases

Pregnant people

Rubella infection during pregnancy can lead to miscarriage, stillbirth and congenital rubella syndrome (CRS). The risk and severity of fetal complications depend on the gestational age at the time of infection:

• 8 to 10 weeks: up to 90% of surviving infants have congenital abnormalities
• 11 to 16 weeks: risk of neurological damage decreases to around 10 to 20%
• After 16 weeks: risk of neurological damage is rare, though sensorineural deafness has been reported with infections up to 20 weeks ¹

Congenital rubella syndrome (CRS)

CRS can result in a wide range of abnormalities, including:

• Sensory defects: hearing impairment and eye defects such as cataracts and retinopathy
• Cardiac abnormalities: patent ductus arteriosus and pulmonary artery stenosis
• Neurological and developmental issues: microcephaly, developmental delay, autism, and inflammatory lesions in the brain
• Growth and systemic complications: intrauterine growth restriction, hepatic, pulmonary and bone marrow involvement, endocrine disorders such as diabetes mellitus, and thyroid dysfunction ¹

Diagnosis

Prenatal diagnosis involves:

• Detection of rubella-specific IgM in fetal blood
• Detection of rubella RNA via RT-PCR in amniotic fluid, fetal blood, or chorionic villus biopsy

Postnatal diagnosis involves:

• Detection of rubella-specific IgM within the first 6 months of life
• Persistence or rise in rubella-specific IgG after 6 to 12 months
• Detection of viral RNA in nasopharyngeal swabs, urine, or oral fluid using RT-PCR

Management

Treatment is supportive and tailored to organ-specific complications. Management requires a multidisciplinary approach, involving paediatrics, ophthalmology, cardiology, audiology, and neurodevelopmental specialists.

Long-term follow-up is essential to monitor for delayed complications and provide developmental support.⁵

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Reviewer

Dr Ramlingareddy

Senior registrar in internal medicine

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Editor

Dr Jamie Scriven

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References

1. NICE CKS. Rubella. 2023. Available from: [LINK].
2. GOV.UK. MMR for all: general guide. 2025. Available from: [LINK].
3. GOV.UK. Rubella: confirmed cases. 2022. Available from: [LINK].
4. WHO. Total rubella reported cases by WHO region. 2023. Available from: [LINK].
5. Leonor MC, Mendez MD. Rubella. StatPearls. 2025. Available from: [LINK].
6. NICE CKS. Scarlet fever. 2024. Available from: [LINK].
7. Paul SB, Heaton PA. At a glance: Scarlet fever in children. Journal of Family Health Care. 2014. Available from: [LINK].
8. NHS. Roseola. 2023. Available from: [LINK].

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