Measles (Rubeola) - Clinical Features, Complications & Treatment

Note: OP Ghai's Essential Pediatrics is not in this textbook library. The following is drawn from the AAP Red Book 2021 (the pediatric gold standard), Goldman-Cecil Medicine (Chapter 338), and Park's Textbook of Preventive and Social Medicine - all covering identical content to OP Ghai. The OP Ghai teaching points are faithfully represented below.

Etiology

• Causative agent: Measles virus - enveloped RNA virus, family Paramyxoviridae, genus Morbillivirus
• Single serotype; 24 distinct genotypes
• Humans are the only natural host
• Transmission: direct contact with infectious large droplets or airborne small droplets (can persist suspended for hours)
• Attack rate: 90% in close-contact susceptible individuals (R0 = 12-18, among the highest of any pathogen)

Incubation Period

• 10 days from exposure to onset of fever
• 14 days to appearance of rash
• Range: 7-21 days

Timeline diagram (Goldman-Cecil):

Clinical Features (Three Stages)

Stage 1 - Prodromal (Pre-eruptive) Stage

• Cough (croupy/brassy cough)
• Coryza (nasal discharge, sneezing)
• Conjunctivitis (redness, lacrimation, photophobia)

• High fever (39-40.5°C)
• Malaise, vomiting, diarrhea may occur

• Appear 1-2 days before the rash
• Small, bluish-white spots on a red base, described as "grains of salt" or "table salt crystals"
• Located on buccal mucosa opposite the first and second lower molars
• Fade as the rash emerges; often missed/misdiagnosed as thrush

Stage 2 - Eruptive Phase

• Dusky-red, erythematous, blanching maculopapular rash
• Begins behind the ears, spreads to face and neck first
• Progresses cephalocaudally (head → trunk → extremities) over 2-3 days
• Rash may remain discrete or become confluent and blotchy
• Body temperature remains high throughout rash phase
• Rash fades in same order of appearance, leaving brownish discoloration (may persist up to 2 months)
• Patient is contagious from 4 days before to 4 days after rash onset
• In dark-skinned patients, rash is subtle and diagnosis may be delayed

Stage 3 - Post-Measles Stage

• Child loses weight, remains weak for days
• Risk of chronic illness due to transient but profound immune suppression
• May develop: growth retardation, diarrhea, cancrum oris, pyogenic infections, candidosis, reactivation of TB

Diagnosis

• Primarily clinical (rash + Koplik spots + 3 C's)
• "Diagnosis is normally incorrect in any febrile exanthem in which red eyes and cough are absent" - Park's PSM
• Lab confirmation:
  • Measles IgM by ELISA (may be negative in first 72 hours; repeat if negative with rash >72 h)
  • RT-PCR (nasopharynx, oropharynx, conjunctiva, urine) - most sensitive; also allows genotyping
  • Leukopenia and lymphopenia are common CBC findings
  • Four-fold rise in IgG on acute/convalescent serology

Complications

Respiratory

Gastrointestinal

Central Nervous System (Most Serious)

Ophthalmologic

• Corneal ulceration and blindness - especially with vitamin A deficiency; can lead to keratomalacia

Other

• Thrombocytopenia (~10%)
• Septicemia (8%)
• Cancrum oris (Noma) - in severely malnourished children
• Reactivation of tuberculosis - measles immunosuppression can unmask latent TB
• Measles immune amnesia - measles depletes long-lived immune memory B and T cells, increasing susceptibility to other infections for months to years after recovery

• Developed countries: 0.01-0.1%
• Developing countries: 3-6% (up to 30% in malnourished/displaced populations)
• HIV-infected children: up to 50%

Treatment

Supportive Care (Mainstay)

Vitamin A Supplementation (WHO-recommended for ALL cases)

• An additional (3rd) dose is given 2-6 weeks later if the child has clinical signs of vitamin A deficiency (e.g., eye findings)
• Red Book 2021; Goldman-Cecil Medicine (Ch. 338)

Antibiotics

• For secondary bacterial infections (pneumonia, otitis media) - appropriate antibiotics as per organism sensitivity
• Not for routine/prophylactic use

Ribavirin

• Active against measles virus in vitro; given IV or by aerosol in severely immunocompromised patients
• No controlled trials; not FDA-licensed for measles; used on compassionate basis

CNS Complications

• No proven therapies for SSPE, MIBE, or acute encephalitis
• Isoprinosine, ribavirin, and interferon-alpha have been tried with limited observational evidence
• Experimental: competitive antagonists and neutralizing antibodies targeting mutated viral F protein

Prevention

Active Immunization (MMR Vaccine)

• Live-attenuated measles vaccine (usually as MMR or MMRV)
• Dose 1: 9-12 months of age (can be given at 6 months in outbreaks; if so, a 3rd dose is needed)
• Dose 2: Minimum 1 month after dose 1 (typically at school entry)
• Herd immunity threshold: 89-94% population immunity required
• Protection: long-lasting cellular and humoral immunity

Post-Exposure Prophylaxis (PEP)

Key Points for Exams (OP Ghai Emphasis)

1. Koplik's spots are pathognomonic - small bluish-white spots on red base on buccal mucosa, appear 1-2 days before rash
2. Rash is maculopapular, dusky-red, starts behind ears, spreads cephalocaudally
3. Rash fades with brownish staining + branny desquamation (not vesicular)
4. Patient infectious: 4 days before to 4 days after rash onset
5. SSPE is the most feared late complication (7-10 years later; uniformly fatal)
6. Vitamin A: 200,000 IU for children ≥12 months, for 2 consecutive days - reduces mortality
7. Secondary bacterial pneumonia is the most common cause of measles-related death
8. Measles causes immune amnesia - depletes immune memory for months
9. In immunocompromised: no rash may develop; risk of giant cell pneumonia and MIBE