Measles
A very contagious viral illness causing high fever, the "3 Cs" (cough, coryza, conjunctivitis), and a spreading red rash, preventable by the MMR vaccine.
Emergency Management: Status epilepticus from acute encephalitis requires emergency airway management and IV lorazepam. Severe respiratory distress requires intubation.
Measles is a highly contagious, acute viral respiratory illness caused by the Measles virus (a Morbillivirus). It is characterized by a prodrome of high fever, cough, coryza, and conjunctivitis, followed by pathognomonic Koplik spots and a generalized maculopapular rash.
Detailed Overview
Measles is one of the most highly communicable infectious diseases known, with a basic reproduction number (R0) of 12-18. Transmission occurs via airborne respiratory droplets that can remain suspended in the air for up to two hours. While safe and highly effective live-attenuated vaccines (MMR) exist, declining vaccination rates in some communities have led to resurgent outbreaks. The disease induces a state of profound immune amnesia, leaving the patient susceptible to severe secondary bacterial infections (like pneumonia), which are the leading cause of measles-related mortality.
Epidemiology & Demographics
Primarily affects unvaccinated children. Remains a leading cause of vaccine-preventable deaths globally (~130,000 deaths annually). Endemic in parts of Africa and Asia. In developed nations, outbreaks occur in tight-knit unvaccinated communities.
Etiological Mechanism
Infection by the Measles virus, a single-stranded, negative-sense RNA virus of the Paramyxoviridae family.
Primary Causes
Airborne transmission via inhalation of infectious aerosolized droplet nuclei from an infected person coughing or sneezing.
The virus infects alveolar macrophages and dendritic cells in the respiratory tract. It uses CD150 (SLAM) and Nectin-4 receptors to enter host cells. It spreads to regional lymph nodes, causing a primary viremia, then to the reticuloendothelial system. A secondary, massive viremia distributes the virus to the skin, conjunctiva, respiratory tract, and distant organs. The rash is actually a delayed type hypersensitivity reaction caused by cytotoxic T-cells attacking virus-infected endothelial cells in the skin. The virus destroys memory lymphocytes, leading to immune amnesia that lasts for months to years, severely dampening host immunity.
Diagnostic Criteria & Guidelines
Often diagnosed clinically during outbreaks. Confirmed by detecting Measles-specific IgM antibodies in serum, or by detecting viral RNA via RT-PCR of throat or nasopharyngeal swabs.
Supportive care: Antipyretics (Acetaminophen or Ibuprofen) for fever, IV fluids for dehydration. Vitamin A supplementation is essential: 200,000 IU for children >1 year given orally for 2 consecutive days (reduces morbidity and mortality).
Second-Line & Adjunctive Therapy
Treatment of secondary bacterial complications (e.g., Amoxicillin for otitis media or Ceftriaxone for secondary pneumonia). Ribavirin may be considered in severe cases in immunocompromised patients, though efficacy is unproven.
Surgical & Procedural Management
None.
Patient Counseling & Advice
Explain that the disease must run its course over about 2 weeks. Warn parents to look out for signs of pneumonia (rapid breathing) or encephalitis (excessive sleepiness, seizures) and to seek immediate care if they occur.
Follow-Up & Monitoring Schedule
Clinical monitoring for complete resolution of fever. Post-measles patients remain susceptible to other infections for several months due to immune amnesia.
Preventive Strategies
Universal immunization with the live-attenuated MMR vaccine. First dose at 12-15 months; second dose at 4-6 years. Post-exposure prophylaxis with vaccine within 72 hrs or IVIG within 6 days for high-risk contacts.
Most recover fully with lifelong immunity. However, mortality is high (up to 10%) in malnourished populations or immunocompromised patients.