*Low-grade fever*, usually <38.5°C.

*Post-auricular, posterior cervical and suboccipital lymphadenopathy* — tender, appears 1 week before rash.

Prodrome is mild: malaise, mild headache, low fever, sore throat.

*Maculopapular rash*:

– Begins on face → spreads to trunk and limbs within hours.

– Pink, discrete lesions.

– Clears completely in 3 days (“3-day measles”).

Forchheimer spots — *petechiae on the soft palate*, seen in ~20%.

Arthralgia/arthritis:

– Common in adult females (up to 70%).

– Usually symmetrical, involving fingers, wrists, knees.

Retroauricular and occipital tenderness during lymphadenopathy.

Mild upper respiratory findings (pharyngeal erythema, coryza minimal).

Child usually not toxic; appears relatively well compared to measles.

Complications uncommon but include thrombocytopenia and encephalitis.

Congenital rubella infection leads to *sensorineural deafness, cataract, PDA* (if infection in 1st trimester).

General complications (rare):

– Arthralgia / arthritis (common in adult females)

– Thrombocytopenia

– Post-infectious encephalitis (1 in 6,000 cases)

– Peripheral neuritis (rare)

Hematologic:

– Transient thrombocytopenic purpura

– Mild leukopenia

Neurologic:

– Encephalitis (rare but serious)

– Guillain–Barré–like neuropathy (rare)

Congenital Rubella Syndrome (CRS) — *most significant complication*:

* – Sensorineural deafness (most common)

* – Congenital cataracts

* – Cardiac defects: PDA, pulmonary artery stenosis

* – Microcephaly

* – Developmental delay

* – Hepatosplenomegaly

* – “Blueberry muffin” rash due to extramedullary hematopoiesis

– Intrauterine growth restriction

– Bone radiolucencies (long bones)

– Endocrine: diabetes, thyroid dysfunction (late manifestations)

Maternal complications:

– Arthritis/arthralgia (up to 70% in adult women)

– Mild hepatitis

– High fever, 3C’s (cough, coryza, conjunctivitis)

– Koplik spots present (absent in rubella)

– Rash darker, confluent; more toxic appearance

– Sandpaper rash, Pastia lines

– Strawberry tongue

– Exudative tonsillitis (not a feature of rubella)

– “Slapped-cheek” rash with lacy reticular pattern

– Often afebrile or mild fever

– High fever → sudden rash after fever resolves

– Rash mainly trunk, child otherwise well

– Variable rash; often associated with herpangina or hand-foot-mouth

– Generalized lymphadenopathy

– Atypical lymphocytes

– Rash often after amoxicillin

– Temporal relation to drug

– Often pruritic; eosinophilia possible

– Retro-orbital pain, leukopenia, thrombocytopenia

– Hemorrhagic signs possible

– Rash can mimic rubella in early phase

Rubella is caused by the **Rubella virus**, a single-stranded, positive-sense enveloped RNA virus belonging to the **genus Rubivirus** under the **Togaviridae** family.

Humans are the only known reservoir; there is **no zoonotic source**.

Transmission is primarily through **respiratory droplets**, close contact, and congenital (vertical) transmission from infected mother to fetus.

The virus replicates initially in the nasopharynx and regional lymph nodes, followed by viremia.

— appears within a few days of rash; confirms acute infection.

—fourfold rise between acute and convalescent samples (2–3 weeks apart).

PCR for rubella RNA (nasopharyngeal swab, throat swab, urine) — sensitive in early infection.

Full blood count:

– Mild leukopenia.

– Relative lymphocytosis.

– Thrombocytopenia in rare cases.

Pregnancy evaluation:

– *Rubella IgG avidity test* helps distinguish recent vs past infection.

– TORCH panel if fetal infection suspected.

Ultrasound (pregnancy):

– For congenital rubella: IUGR, microcephaly, cardiac defects, cataracts, hepatosplenomegaly.

Chest X-ray usually normal; may show mild perihilar infiltrates in viral exanthems.

CRP/ESR usually normal or mildly elevated.

In congenital infection:

– RT-PCR on neonatal throat swabs/urine.

– Persistent IgM beyond 6 months suggests chronic congenital rubella.

– High teratogenic potential despite low virulence in general population.

– Koplik spots belong to measles; rubella has Forchheimer spots (petechiae on soft palate).

– Distinguishes rubella from other viral exanthems.

– Patients are contagious for ≈7 days before rash and 7 days after.

– One of the strongest global indications for MMR vaccination.

– Autoimmune-like mechanism; resembles parvovirus-associated arthropathy.

– Immune-mediated platelet destruction.

– Important for diagnosis in pregnancy; repeat testing may be needed.

After entry, local replication occurs in the upper respiratory mucosa and cervical lymph nodes.

Primary viremia follows within 5–7 days of infection, disseminating the virus to multiple organs.

*Secondary viremia occurs just before the onset of rash*, leading to maximal viral shedding and contagiousness.

Virus spreads to skin, producing the characteristic *erythematous maculopapular rash* through immune-mediated mechanisms rather than direct cytopathic effect.

Lymphadenitis (especially *post-auricular and suboccipital nodes*) results from viral replication in regional lymphoid tissue.

In adults, arthralgia and arthritis result from *immune complex deposition* in synovial membranes.

*Rubella is generally non-cytolytic*; clinical manifestations arise mainly from the host immune response.

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### Congenital Rubella Pathogenesis (for teaching)

Transplacental transmission occurs during maternal viremia.

*First trimester infection is most dangerous*, as the virus targets rapidly dividing embryonic cells.

Rubella inhibits cell division, disrupts organogenesis, and causes chronic fetal infection.

Persistent fetal viremia results in *congenital rubella syndrome (CRS)* affecting eyes, ears, heart, and CNS.

– Prominent enlargement of cervical, post-auricular, and occipital lymph nodes.

– Virus replicates in respiratory mucosa → regional lymph nodes → bloodstream.

– Endothelial injury causes mild rash (immune-complex mediated).

– Maculopapular rash results from deposition of antigen–antibody complexes in dermal capillaries.

– Viral replication in fetal tissues → cell death, necrosis, and impaired organogenesis.

– Most affected: heart (PDA), lens (cataract), cochlea, brain (microcephaly).

– Persistent fetal infection can cause chronic inflammation and fibrosis.

– Occasionally causes transient thrombocytopenia.

Routine childhood vaccination:

– 1st dose at 9–12 months

– 2nd dose at 15–18 months or school entry (depending on national schedule)

Adult vaccination:

– All non-immune adults (especially women of childbearing age) should receive MMR.

Pregnancy considerations:

– *Live vaccine — contraindicated during pregnancy.*

– Women should avoid conception for 4 weeks after MMR vaccination.

Postpartum immunization:

– Non-immune mothers should be vaccinated immediately after delivery.

Outbreak control:

– Identify and vaccinate susceptible contacts.

– Exclude unvaccinated individuals from high-risk settings (schools, hostels) during outbreaks.

Healthcare workers:

– Ensure documented immunity to rubella (vaccination or serology).

Herd immunity:

– High community vaccination coverage prevents circulation of the virus and protects pregnant women.

Congenital Rubella Syndrome (CRS) prevention:

– *Prevention of maternal infection is the only strategy.*

– Uncomplicated rubella rarely produces pneumonia.

– Seen only in moderate infection or in immunocompromised patients.

– Neuroimaging (USG/CT/MRI) may show:

• Intracranial calcifications (basal ganglia or periventricular)

• Microcephaly

• Ventriculomegaly

• White-matter injury

• Cerebellar hypoplasia

– Echocardiography may show PDA, pulmonary artery stenosis, VSD.

– Rubella virus has a single antigenic serotype worldwide.

– Genotype 1

– Genotype 2

– Genotypes differ genetically but **do not differ clinically** and do **not affect immunity**.

– Natural infection or vaccination provides durable protection against all strains.

– Unlike influenza, rubella shows **minimal antigenic variation**.

*Post-auricular, suboccipital and posterior cervical lymphadenopathy* — most classic sign.

*Mild, discrete maculopapular rash beginning on the face and spreading to trunk and extremities*, clears within 3 days.

Rash is pink, non-coalescing, and lighter than measles.

Forchheimer spots — *reddish petechiae on the soft palate* (seen in ~20%).

*Mild conjunctivitis* (non-purulent).

Low-grade fever (often <38.5°C).

Faint facial erythema at onset.

Retroauricular tenderness during lymphadenopathy.

Occasional arthralgia/arthritis on examination (more common in adults).

Mild upper respiratory findings (pharyngeal erythema).

No Koplik spots (important differentiator from measles).

No significant toxicity; child often appears well.

Splenomegaly is rare but may occur.

Rubella is an acute, generally mild viral infection caused by a Togavirus (Rubella virus).

It presents with low-grade fever, tender postauricular and suboccipital lymphadenopathy, and a faint pink maculopapular rash lasting 1–3 days.

While illness is usually mild in children and adults, **maternal infection in early pregnancy can lead to congenital rubella syndrome (CRS)**, causing serious fetal abnormalities.

*Low-grade fever*, usually <38.5°C.

*Post-auricular, suboccipital and posterior cervical lymphadenopathy* — often the earliest sign.

Headache, malaise, mild upper respiratory symptoms (coryza, sore throat).

*Arthralgia and arthritis are common in adolescents and adults*, especially females.

Conjunctivitis (mild, non-purulent).

*Maculopapular rash starting on the face and spreading caudally*, fading within 3 days (“*3-day measles*”).

Rash is lighter and more subtle than measles; not typically confluent.

Forchheimer spots may occur — *petechiae on the soft palate* (seen in ~20%).

Myalgia and low-grade fatigue.

Photophobia (mild).

GI upset (rare).

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### Symptoms in Congenital Rubella Syndrome (CRS) — for teaching reference

*Sensorineural hearing loss* (most common complication).

*Congenital cataracts, retinopathy*, microphthalmia.

*Congenital heart disease* — PDA, pulmonary artery stenosis.

Microcephaly, developmental delay.

Purpuric “*blueberry muffin*” rash (extramedullary hematopoiesis).

Fever control with paracetamol.

Adequate hydration and rest.

Antihistamines for pruritic rash (if bothersome).

Arthralgia-predominant cases (usually adult females):

– NSAIDs for joint pain (short course only).

Avoid aspirin in children (risk of Reye syndrome).

Congenital Rubella Syndrome (CRS):

– Multidisciplinary management (cardiology, ophthalmology, audiology, neurology).

– Early hearing assessment + cochlear/assistive support.

– Surgical correction for congenital cataracts or cardiac defects when indicated.

– Developmental assessment and early intervention therapy.

Isolation:

– *Patients should avoid contact with pregnant women* until 7 days after rash onset.

Post-exposure:

– *Rubella vaccine is NOT used for post-exposure prophylaxis.*

– Immune globulin may be used only in pregnant women with documented exposure who decline termination, but protection is incomplete.