- Genus: Morbillivirus
- Family: Paramyxoviridae
- Single-stranded, linear, negative-sense RNA virus
- Enveloped virus
- Large helical capsid carries RNA-dependent RNA polymerase in virion.
Epidemiology and Pathogenesis
- Incidence: 50–300/year in the United States
- Mainly a childhood disorder
- Since 2-dose measles, mumps, rubella (MMR) vaccination, US cases ↓ 99%
- Incidence: males = females
- Higher mortality observed in women at all ages
- Fatality rate 4%–10% in developing countries
- Highly contagious → 90% secondary infection rate: CDC–reportable disease
- Humans are the only known reservoir.
- Respiratory droplets
- Person-to-person contact
- Young children and pregnant women are particularly susceptible to infection.
Clinically relevant species
- Paramyxoviridae family:
- Paramyxovirus: includes parainfluenza viruses and mumps virus
- Pneumovirus: includes respiratory syncytial virus
- Morbillivirus: includes measles virus
- Paramyxoviridae family causes 30%–40% of all acute respiratory infections in infants and children.
- Incubation period: 2–3 weeks
- Virus enters via upper respiratory tract → infects local lymphatic tissues → amplification in regional lymph nodes → dissemination to various organs (testes, ovaries, thyroid gland, pancreas, and central nervous system)
- 2 envelope glycoproteins bind to host cells:
- Hemagglutinin (H)
- Fusion protein (F)
- Negative-sense strand ssRNA (single-stranded RNA) used as template strand for positive strand
- ssRNA translated by host ribosomes → produces proteins
- Viruses are packaged while host cells undergo lysis.
- Generalized immunosuppression:
- Suppression of interferon production through nonstructural proteins V and C
- ↓ In delayed-type hypersensitivity
- ↓ Interleukin (IL)-12 production
- ↓ Antigen-specific lymphoproliferative responses
- Prodromal stage:
- High fever
- Day 3: Koplik’s spots (bluish-gray grain of salt with red halo, 1–2 days)
- Day 4: maculopapular rash (from head/neck → body)
At least 1 complication occurs in 30% of cases:
- Immune suppression and secondary infection:
- Secondary infection can be with viruses or bacteria.
- Tuberculosis reactivation has been described.
- Most common
- Seen in 8% of cases
- Most deadly complication
- Seen in 6% of cases
- Otitis media
- Giant cell pneumonia:
- Seen in individuals with cellular immunity deficiencies (e.g., leukemia, AIDS)
- Often fatal
- Acute disseminated encephalomyelitis (ADEM):
- Postinfectious inflammation of central nervous system
- Symptoms include weakness, fatigue, and blindness.
- Subacute sclerosing panencephalitis:
- Fatal degenerative disease of CNS
- Occurs 7–10 years after infection
- Poorly understood
- Blindness: due to keratitis and corneal ulceration
The disease is diagnosed on clinical suspicion followed by confirmatory laboratory testing. Suspected cases should be isolated until confirmed.
- History reveals trio of symptoms: cough, coryza, conjunctivitis
- Exam confirms maculopapular rash.
- Diagnosis made by 1 of 3:
- Hemagglutination inhibition:
- Rapid ↑ in IgG titers
- Positive IgM
- RT-PCR with detection of measles RNA
- Hemagglutination inhibition:
- Consider lumbar puncture if concern for encephalitis.
- Consider chest X-ray in patients with hypoxia and concern for pneumonia.
- Supportive care:
- Fever reduction
- Superinfection prevention measures
- High-dose vitamin A:
- In patients with known nutritional deficiencies
- 2-dose IM injection has been shown to ↓ morbidity and mortality in children < 5 years of age
- Used in cases of pneumonia
- Reduces duration of symptoms and hospitalization
- Reduces morbidity and mortality
- Vaccination counselling
- MMR triple vaccine:
- Children should get 2 doses.
- 1st dose at 12–15 months and 2nd at 4–6 years
- Can be given to all ages
- MMRV vaccine (measles, mumps, rubella, and varicella):
- Children up to age 12 should get 2 doses.
- Only approved for children who are 12 months to 12 years of age
- 1st dose at 12–15 months and 2nd dose at 4–6 years
- Infection gives lifelong immunity.
Comparison of Common Childhood Rashes
|Number||Other names for the disease||Etiology||Description|
|1st disease||Measles morbillivirus|
|2nd disease||Streptococcus pyogenes|
|3rd disease||Rubella virus|
|4th disease||Due to Staphylococcus aureus strains that make epidermolytic (exfoliative) toxin|
|5th disease||Erythema infectiosum||Erythrovirus or parvovirus B19 (Primate erythroparvovirus 1)|
|6th disease||Human herpesvirus 6B or 7|
- Perry RT, Halsey NA. (2004). The clinical significance of measles: a review. J Infect Dis. 189 Suppl 1:S4–16. https://pubmed.ncbi.nlm.nih.gov/15106083/
- Richardson M, et al. (2001). Evidence base of incubation periods, periods of infectiousness and exclusion policies for the control of communicable diseases in schools and preschools. Pediatr Infect Dis J. 20(4),380–391. https://pubmed.ncbi.nlm.nih.gov/11332662/
- Zenner D, Nacul L. (2012). Predictive power of Koplik’s spots for the diagnosis of measles. J Infect Dev Ctries. 6(3),271–275. https://pubmed.ncbi.nlm.nih.gov/22421609/
- Cherry JD. (2009). Measles virus. In: Textbook of Pediatric Infectious Diseases, 6th ed. Feigin RD., et al. (Eds.). Saunders. Philadelphia. pp.2427.
- Atkinson W, Wolfe C, Hamborsky J. (Eds.). (2011). Epidemiology and Prevention of Vaccine-Preventable Diseases (The Pink Book), 12th ed. The Public Health Foundation. Washington, DC.
- Beckford AP, Kaschula RO, Stephen C. (1985). Factors associated with fatal cases of measles. A retrospective autopsy study. S Afr Med J. 68(12),858–863. https://pubmed.ncbi.nlm.nih.gov/3877996/
- Chen, S. (2019). Measles. Emedicine. Retrieved February 5, 2021, from: https://emedicine.medscape.com/article/966220-overview#a4