What are the potential complications of measles, particularly in pediatric patients and those with compromised immune systems?

Complications of Measles

Life-Threatening Complications

Pneumonia is the most common cause of measles-related death, followed by acute encephalitis, with an overall mortality rate of 1-2 per 1,000 cases in the United States. 1, 2

Respiratory Complications

• Pneumonia represents the leading fatal complication and occurs frequently enough to warrant early antibiotic therapy in severe cases 1, 2
• Adult respiratory distress syndrome (ARDS) develops in the most critically ill patients, particularly those requiring intensive care, and carries high mortality even with modern ventilatory support 3
• Spontaneous pneumothorax complicates severe pneumonia cases, occurring in approximately 20% of patients requiring intensive care 3
• Bronchopneumonia follows diarrhea and otitis media as the third most common complication overall 1

Neurological Complications

• Acute encephalitis occurs in approximately 1 per 1,000 measles cases and represents a major cause of mortality 1, 4
• Subacute sclerosing panencephalitis (SSPE) is a rare but invariably fatal late complication appearing years after the initial infection, even in immunologically normal individuals 1, 2
• Permanent brain damage can result from acute encephalitis in survivors 1
• Encephalopathy was documented in nearly half (7 of 15) of children requiring intensive care in one case series 3

Gastrointestinal and Other Common Complications

• Diarrhea is the single most common complication of measles 1, 4
• Otitis media (middle ear infection) ranks as the second most frequent complication 1, 4
• Secondary bacterial infections occur early and prominently, with sepsis documented in one-third of intensive care patients 3

High-Risk Populations with Increased Morbidity and Mortality

Age-Related Risk

• Infants and young children under 3 years face the highest mortality risk, with peak deaths occurring in the first three years of life 2, 5
• Adults experience higher complication rates than older children and adolescents 1, 2

Immunocompromised Patients

• Severely immunocompromised individuals (particularly those with leukemia, lymphoma, or HIV infection) may develop severe, prolonged infection that sometimes presents without the typical rash 1, 2
• Patients on high-dose corticosteroids (≥20 mg/day prednisone for >2 weeks) are considered immunosuppressed and at higher risk 6
• The mortality and morbidity risk is substantially elevated in this population, though specific quantification varies by degree of immunosuppression 1

Pregnant Women

• Pregnancy increases rates of premature labor, spontaneous abortion, and low birth weight infants 1, 4, 2
• Maternal and fetal mortality risk is elevated compared to non-pregnant women 2

Malnourished Children

• Malnutrition significantly increases mortality risk, particularly in developing countries where case fatality rates can reach 25% compared to 1-2 per 1,000 in the United States 1, 2
• In one intensive care case series, 11 of 15 critically ill children were malnourished 3

Additional Severe Complications in Critical Cases

• Hypoxemia requiring mechanical ventilation develops in the most severe respiratory cases, with 12 of 15 intensive care patients being severely hypoxemic before intubation 3
• Empyema complicates pneumonia in some cases 3
• Shock occurred in 20% of intensive care admissions 3
• Coagulopathy and thrombocytopenia were documented in nearly half of intensive care patients 3
• Hypocalcemia affected 73% of intensive care patients 3
• Thrombus formation developed during treatment in 20% of intensive care cases 3

Long-Term Sequelae

• Chronic lung disease (fibrosing alveolitis) can develop in survivors of severe pneumonia 3
• Hemiplegia from brain infarction may occur 3
• Limb amputation may be required in cases complicated by severe thrombosis 3
• Four of 15 intensive care survivors in one series had permanent long-term complications 3

Clinical Pitfalls

The high frequency of secondary bacterial infections means antibiotics should be instituted early in severe cases rather than waiting for definitive evidence of bacterial superinfection 3. Additionally, even patients who experience uncomplicated acute measles retain a small but real risk of developing SSPE years later, emphasizing that no case of measles is truly "benign" 7.