Rubeola :: Measles - Cards (ver10)

Summary / Overview

The virus spreads through airborne respiratory droplets and remains suspended in air for up to 2 hours
Natural infection produces **lifelong immunity**.

Etiology

Caused by the Measles virus — an enveloped, single-stranded, negative-sense RNA virus.
H protein mediates viral attachment to host receptors SLAM (CD150) and Nectin-4.
F protein enables membrane fusion and formation of multinucleated giant cells (syncytia).

Pathogenesis

Primary replication in respiratory epithelium
Viremia spreads virus to reticuloendothelial system
Immune-mediated rash formation

Symptoms

High fever 103–105°F (39.5–40.5°C)
3 C’s: Cough, Coryza, Conjunctivitis
Koplik spots — appear before rash
Koplik spots

Signs

Generalized maculopapular rash
Confluent rash starting at hairline
Koplik spots (pathognomonic)
• Fever 103–105°F (39.5–40.5°C)
• Conjunctivitis with photophobia
• Coryza (“snuffy nose”)

Clinical Features

Three C’s: Cough, Coryza, Conjunctivitis
Koplik spots precede rash by 1–2 days
Cephalocaudal rash progression
• Incubation: 10–14 days
• Exanthem:

Differential Diagnosis

Rubella (German measles)
Roseola (HHV-6/7)
Dengue (rash + myalgia)
• Drug-induced exanthems
• Parvovirus B19 (erythema infectiosum / Fifth disease)
• Enteroviral exanthems

Complications

Pneumonia — most common cause of death
Acute encephalitis
Subacute Sclerosing Panencephalitis (SSPE)

Treatment

Supportive care only — no antiviral
Vitamin A reduces mortality

Prevention

MMR vaccine — highly effective
Routine childhood immunization prevents outbreaks

Serotypes / Subtypes

Single serotype

Pathology

Warthin–Finkeldey giant cells (pathognomonic)
Multinucleated giant cells in lymphoid tissue

Radiology / Imaging

• Viral pneumonia pattern
Rubella rarely requires imaging
When pulmonary involvement occurs, pattern resembles general viral pneumonitis

Notes / Teaching points

Koplik spots are pathognomonic
Highly contagious: R0 = 12–18
Vitamin A deficiency worsens disease

Three C’s: Cough, Coryza, Conjunctivitis

Koplik spots precede rash by 1–2 days

Cephalocaudal rash progression

• Incubation: 10–14 days

• Prodrome: 3–5 days of high fever + 3 C’s

• Enanthem: Koplik spots on buccal mucosa

• Exanthem:

– Erythematous maculopapular rash

– Begins at hairline, spreads downward

– Becomes confluent on face & trunk

• Resolution:

– Rash darkens → desquamates

– Fever settles after rash peaks

• Highly contagious: 4 days before to 4 days after rash

• Photophobia common

Pneumonia — most common cause of death

Acute encephalitis

Subacute Sclerosing Panencephalitis (SSPE)

• Otitis media

• Severe diarrhea → dehydration

• Laryngotracheobronchitis (croup)

• Keratitis → blindness (vitamin A deficiency)

• Hepatitis (rare)

• Febrile seizures

• Pregnant women: miscarriage, preterm labour

• Immunocompromised: giant cell pneumonia, severe disease

SSPE appears 7–10 years after infection.

Rubella (German measles)

Roseola (HHV-6/7)

Dengue (rash + myalgia)

• Scarlet fever

• Varicella (chickenpox)

• Drug-induced exanthems

• Kawasaki disease

• Parvovirus B19 (erythema infectiosum / Fifth disease)

• Enteroviral exanthems

• COVID-19 (in some children)

Caused by the Measles virus — an enveloped, single-stranded, negative-sense RNA virus.

The Measles virus belongs to the genus *Morbillivirus* and the family *Paramyxoviridae*.

It is a pleomorphic, enveloped virus with a helical nucleocapsid and two major surface

glycoproteins: **Hemagglutinin (H)** and **Fusion (F)** proteins.

H protein mediates viral attachment to host receptors SLAM (CD150) and Nectin-4.

F protein enables membrane fusion and formation of multinucleated giant cells (syncytia).

There is only **one serotype** of measles virus. Multiple genotypes (A, B1–B3, C1–C2,

D1–D11, E, F, G1–G3, H1–H2) exist, but they do not significantly affect immunity or

clinical disease.

Humans are the **only reservoir**; no animal hosts are involved.

*Transmission is airborne*, via respiratory droplets and aerosolized particles.

The virus remains suspended and infectious in air for **up to 2 hours**.

*Extremely high contagiousness:* reproduction number (R0) **12–18**, among the highest of all viruses.

Koplik spots are pathognomonic

Highly contagious: R0 = 12–18

Vitamin A deficiency worsens disease

• Measles suppresses immune memory (“immune amnesia”)

• Mortality highest in malnourished children

• SSPE: late fatal neurological disease

• Rash appears when immune system attacks infected cells

Primary replication in respiratory epithelium

Viremia spreads virus to reticuloendothelial system

Immune-mediated rash formation

• Entry via respiratory droplets

• Virus binds CD150 (SLAM) receptors on dendritic cells, macrophages & lymphocytes

• Transport to regional lymph nodes → **primary replication**

• **Primary viremia** spreads virus to:

– spleen

– liver

– thymus

– bone marrow

• **Secondary viremia** disseminates virus to:

– skin

– conjunctiva

– respiratory epithelium

– GI mucosa

• **Rash mechanism**

– not viral cytopathy

– **T-cell immune response** against measles-infected endothelial cells

• Causes **profound immune suppression** lasting weeks

• Leads to ↑ risk of otitis media, pneumonia, diarrhea

• Rarely infects CNS → acute encephalitis or SSPE

Warthin–Finkeldey giant cells (pathognomonic)

Multinucleated giant cells in lymphoid tissue

• Primary replication: nasopharynx & lymph nodes

• Viremia spreads virus to:

– skin

– conjunctiva

– respiratory epithelium

– GI tract

– CNS

• Immunosuppression for weeks → secondary infections

MMR vaccine — highly effective

Routine childhood immunization prevents outbreaks

• 1st dose: 9–12 months (Bangladesh/India schedules)

• 2nd dose: 15–18 months or 4–6 years

• Post-exposure prophylaxis:

– MMR within 72 hours

– Immunoglobulin for immunocompromised & pregnant

• Isolation of infected patient

• Good nutrition & vitamin A status reduce severity

• Viral pneumonia pattern

• Hyperinflation in children

• Patchy bilateral infiltrates

• Peribronchial cuffing

• In severe cases: giant cell pneumonia (rare)

Rubella rarely requires imaging

When pulmonary involvement occurs, pattern resembles general viral pneumonitis

Chest radiograph typically shows:

- Perihilar peribronchial thickening

- Interstitial infiltrates

- Hyperinflation in children

- No focal lobar consolidation (helps distinguish from bacterial pneumonia)

Note: Teaching references often use “viral pneumonitis pattern X-rays” because rubella-specific radiology is uncommon but the general viral pattern is relevant.

References

Dept_reference Viral pneumonitis

Dr Sankaran • 2025-11-17 12:41:44

Dept_reference

Dr Sankaran • 2025-11-17 12:29:19

Dept_reference

Dr Sankaran • 2025-11-17 12:29:08

Single serotype

• Measles virus (paramyxovirus) has **one serotype**

• Several genotypes exist (A, B, C, D, G, H groups)

• Vaccine derived from genotype A

• Immunity cross-protects against all genotypes

Generalized maculopapular rash

Confluent rash starting at hairline

Koplik spots (pathognomonic)

• Fever 103–105°F (39.5–40.5°C)

• Toxic, ill-appearing

• Conjunctivitis with photophobia

• Coryza (“snuffy nose”)

• Harsh barking cough

• Lymphadenopathy (post-auricular & cervical)

• Pharyngeal erythema

• Periorbital edema (occasionally)

• Diarrhea (children)

Koplik spots appear 1–2 days before the rash

and fade as the rash progresses.

*Measles (Rubeola)* is a highly contagious acute viral illness caused by the Measles virus,

a single-stranded, negative-sense RNA virus of the genus *Morbillivirus* (family Paramyxoviridae).

The virus spreads through airborne respiratory droplets and remains suspended in air for up to 2 hours

even after an infected person has left the area. Infectivity begins 4 days before rash onset and continues

until 4 days after rash appearance.

Measles is one of the most transmissible infections known, with a secondary attack rate approaching *90%*

among susceptible contacts. Outbreaks occur in communities with low vaccination coverage.

Clinical disease is characterized by *high fever, cough, coryza, conjunctivitis*, Koplik spots, and a

cephalocaudal spreading maculopapular rash. Complications include pneumonia, acute encephalitis,

and *subacute sclerosing panencephalitis (SSPE)*.

Measles is preventable through the *MMR (Measles–Mumps–Rubella)* vaccine, which provides long-lasting

protective immunity and is the cornerstone of global measles elimination strategies.

Natural infection produces **lifelong immunity**.

High fever 103–105°F (39.5–40.5°C)

3 C’s: Cough, Coryza, Conjunctivitis

Koplik spots — appear before rash

• Fever for 3–5 days

• Barking or dry cough

• Runny nose (coryza)

• Red eyes with photophobia

• Fatigue, malaise

• Body aches

• Sore throat

• Poor appetite

• Diarrhea (common in children)

Koplik spots

– Small bluish-white lesions on buccal mucosa

– Appear 1–2 days before rash

– Disappear as rash spreads

Supportive care only — no antiviral

Vitamin A reduces mortality

• Antipyretics (paracetamol)

• Adequate hydration

• Honey + warm fluids for cough

• Avoid aspirin (risk of Reye syndrome)

• Vitamin A:

– <1 year: 100,000 IU/day × 2 days

– >1 year: 200,000 IU/day × 2 days

• Antibiotics only for secondary bacterial infections

• Isolation: 4 days after rash onset

Hospitalization if:

– Respiratory distress

– Dehydration

– Altered sensorium

– Severe diarrhea

– Pneumonia