Summary of "Measles - causes, symptoms, diagnosis, treatment, pathology"

Main Ideas and Concepts:

Contagiousness and Cause:
- Measles is one of the most contagious infectious diseases, especially dangerous for young children in areas with low vaccination rates.
- It is caused by the Measles virus (species: Measles virus; genus: Morbillivirus; family: Paramyxoviridae).
- Measles is airborne, spreading via tiny liquid particles from coughs or sneezes, remaining infectious in the air or on surfaces for up to two hours.
- If one person has Measles, 90% of nearby non-immune people will likely become infected.
Virus Entry and Replication:
- The virus infects epithelial cells in the respiratory tract using the hemagglutinin (H) protein to bind to receptors (CD46, CD150/SLAM, or nectin-4) on host cells.
- Fusion (F) protein facilitates viral entry into cells.
- It is a single-stranded, negative-sense RNA virus that must be transcribed into positive-sense mRNA before protein synthesis.
- Virus spreads locally in lung tissue, then via immune cells to lymph nodes, bloodstream, and other organs (intestines, brain).
Incubation and Symptom Progression:
- Incubation period: 10–14 days (virus enters body to symptom onset).
- Prodromal period (~3 days): high fever, the "three C’s" — cough, conjunctivitis, coryza (nasal mucous membrane swelling).
- Enanthem phase: appearance of Koplik spots (small white spots on inside cheeks).
- Exanthem phase: red, blotchy maculopapular rash spreading from head downward (cephalocaudal progression).
- Rash fades after ~4 days, followed by recovery phase lasting 10–14 days, often ending with a persistent cough.
- Contagious period: ~4 days before to 4 days after rash onset.
Complications:
- Can affect lungs, intestines, brain.
- Common complications: pneumonia, diarrhea, encephalitis.
- Measles suppresses immune system for up to six weeks, increasing risk of bacterial superinfections (otitis media, bacterial pneumonia).
- Highest mortality among young infants.
- Subacute sclerosing panencephalitis (SSPE) is a rare, fatal, delayed complication occurring 7–10 years post-infection, causing chronic brain inflammation.
- Immunocompromised individuals (e.g., HIV/AIDS) may not develop typical symptoms but have higher risk of severe pneumonia and encephalitis.
Diagnosis:
- Usually confirmed by serology detecting Measles antibodies in blood serum.
- Most cases occur in unvaccinated individuals.
Prevention:
- Measles vaccine is a live attenuated virus given at 12–15 months and again at 4–6 years.
- Vaccine efficacy is about 95%.
- Maternal antibodies provide protection to infants up to about 9 months.
- During outbreaks, vaccination of household contacts and administration of Measles immunoglobulin to pregnant women and infants can help prevent spread.
Treatment:
- No specific antiviral treatment exists.
- Supportive care includes hydration, pain relief, and treatment of secondary bacterial infections.
- Vitamin A supplementation is recommended for young children and severely malnourished patients to boost immune response and reduce complications.

Methodology / Key Points Summary:

Transmission:
- Airborne droplets (coughs, sneezes)
- Virus survives ~2 hours in air or on surfaces
- Highly contagious: 90% infection rate among non-immune close contacts
Virus-Host Interaction:
- Binding: Hemagglutinin (H) protein → CD46, CD150/SLAM, or nectin-4 receptors
- Fusion: Fusion (F) protein enables viral entry
- RNA virus: negative-sense ssRNA → transcribed to positive-sense mRNA → protein synthesis
Clinical Course:
- Incubation: 10–14 days
- Prodromal: fever + cough + conjunctivitis + coryza
- Enanthem: Koplik spots inside cheeks
- Exanthem: maculopapular rash spreading head to feet
- Recovery: rash fades, persistent cough may remain
Complications:
- Pneumonia, diarrhea, encephalitis
- Immune suppression → bacterial superinfections
- SSPE (rare, delayed neurological complication)
Diagnosis:
- Serology for Measles antibodies
Prevention:
- Live attenuated vaccine at 12–15 months