What are the side effects and complications of measles infection?

Measles Side Effects and Complications

Immediate Clinical Manifestations

Measles infection causes a characteristic prodrome of high fever (≥38.3°C), cough, coryza (runny nose), and conjunctivitis, followed by a maculopapular rash that begins on the face and spreads downward to the trunk and extremities. 1, 2

• The incubation period averages 10-12 days from exposure to prodrome and 14 days to rash onset (range 7-18 days) 1, 2
• Koplik spots (small white spots on red background inside the mouth) appear during prodrome and are pathognomonic for measles 1
• Patients remain contagious from 4 days before rash onset through 4 days after rash appears 1, 2

Common Complications

Diarrhea is the most frequent complication, followed by otitis media (middle ear infection) and bronchopneumonia. 1, 2

• Approximately 23% of measles cases require hospitalization in developed countries 3
• Pneumonia represents the leading cause of measles-related death 4, 1
• Secondary bacterial infections commonly complicate the clinical course and require prompt antibiotic treatment 3, 1
• Stomatitis and oral candidiasis may develop due to measles-induced immunosuppression 1

Neurological Complications

Acute encephalitis occurs in approximately 1 per 1,000 measles cases and is a leading cause of measles mortality and permanent brain damage. 3, 4, 1

• Before vaccination programs, measles encephalitis caused approximately 1,000 cases of permanent brain damage annually in the United States 3
• Acute disseminated encephalomyelitis can occur during or shortly after acute infection 5
• Subacute sclerosing panencephalitis (SSPE) is a rare but invariably fatal late complication appearing years after infection 4, 1, 5
• Measles inclusion body encephalitis may develop months after infection, particularly in immunocompromised individuals 5

Mortality Risk

The case fatality rate in the United States is 1-2 per 1,000 reported cases (0.1-0.2%), but can reach 25% in developing countries with limited healthcare access. 4, 1, 2

• Infants, young children under 3 years, and adults aged ≥20 years face the highest mortality risk 4, 1
• Before the 1963 vaccine introduction, approximately 500 deaths occurred annually among 500,000 reported U.S. cases 3, 4
• During 2001-2008, only 2 deaths occurred among 557 confirmed U.S. cases, with 5 patients requiring intensive care 3

High-Risk Populations

Immunocompromised individuals, pregnant women, malnourished children, and unvaccinated persons face substantially elevated complication and mortality risks. 4, 1

Immunocompromised Patients

• May develop severe, prolonged infection sometimes without the typical rash 1, 2
• Patients with leukemia, lymphoma, HIV infection, or on high-dose corticosteroids (≥20 mg/day prednisone for >2 weeks) are at highest risk 1
• Can continue shedding virus for weeks after acute illness 1

Pregnant Women

• Experience increased rates of premature labor, spontaneous abortion, and low birth weight infants 4, 1, 2
• Face elevated maternal and fetal mortality risk 4

Malnourished Children

• Malnutrition significantly increases mortality risk, particularly in developing countries 4
• All children with clinical measles should receive vitamin A supplementation (100,000 IU for <12 months; 200,000 IU for ≥12 months) 3, 1
• Children with complicated measles require a second vitamin A dose on day 2 3, 1

Severe Respiratory Complications

Patients requiring intensive care face high mortality risk, with adult respiratory distress syndrome (ARDS) and pneumothorax representing the most severe complications. 6

• Among 15 pediatric intensive care patients, all required mechanical ventilation for severe pneumonia 6
• Seven developed ARDS, three had spontaneous pneumothorax, and four died 6
• Secondary bacteremia occurs early and prominently, requiring early antibiotic initiation 6
• Long-term sequelae included chronic lung disease, SSPE, hemiplegia, and partial limb amputation 6

Vaccine-Modified Disease

Previously vaccinated individuals can develop measles with milder symptoms and fewer complications, though breakthrough infections occur in approximately 1% of two-dose recipients. 2, 7

• Four of nine secondary Colorado outbreak cases occurred in persons with documented two-dose MMR vaccination 7
• Vaccinated patients reported fewer and milder symptoms overall compared to unvaccinated cases 7
• Urine RT-PCR specimens may remain positive longer than nasopharyngeal specimens in vaccinated individuals 7

Critical Clinical Pitfalls

Undernutrition, fever, respiratory infection, and diarrhea are NOT contraindications to measles vaccination—they should be considered strong indications for immediate vaccination. 3

• HIV-infected individuals without severe immunosuppression should receive MMR vaccine 3, 1
• Isolation of measles patients is not indicated in emergency camp settings but requires airborne precautions in healthcare facilities 3, 1
• Measles vaccine administered within 72 hours of exposure may provide protection or modify disease severity 3, 2