Measles - causes, symptoms, diagnosis, treatment, pathology

Summary

Measles is an extremely contagious viral disease, primarily affecting children in areas with low vaccination rates. Caused by the measles virus, it spreads through airborne particles and can lead to severe complications like pneumonia, encephalitis, and even death, especially in young infants. Symptoms include fever, cough, conjunctivitis, and a distinct rash. The disease is preventable via the MMR vaccine, with 95% effectiveness. Treatment is supportive, including hydration and pain relief, while vitamin A may help reduce severe complications. Despite the risk, lifelong immunity is gained after recovery, and vaccination remains the most effective prevention.

Takeaways

• 😀 Measles is one of the most contagious infectious diseases, particularly dangerous for young children, especially in areas with low vaccination rates.
• 😀 Measles is caused by the measles virus (a member of the morbillivirus genus), which spreads via airborne liquid particles from coughing or sneezing.
• 😀 The measles virus can live in the air for up to two hours and spread by touching surfaces or breathing in infected air.
• 😀 Once contracted, the measles virus targets the mucosal cells in the respiratory system, using surface proteins like hemagglutinin (H-protein) to enter the cells.
• 😀 Measles is a single-stranded RNA virus and is 'negative-sense', meaning it must be transcribed into positive-sense mRNA before producing viral proteins.
• 😀 The infection typically takes 10 to 14 days from exposure to the onset of symptoms, marking the incubation period.
• 😀 The prodromal period of measles starts with high fever, cough, conjunctivitis, and a stuffy nose, followed by Koplik spots (white spots inside the mouth).
• 😀 The exanthem phase follows, where a red, blotchy maculopapular rash spreads from the head to the extremities (cephalocaudal progression).
• 😀 People infected with measles are most contagious from the final day of the incubation period through the prodromal and exanthem phases, which is about four days before and after the rash appears.
• 😀 Complications from measles include pneumonia, diarrhea, encephalitis, and, in rare cases, subacute sclerosing panencephalitis (SSPE) in children under two, which can develop years later and is fatal if untreated.
• 😀 The measles vaccine is highly effective (95% efficacy rate) and provides lifelong immunity once someone recovers from the infection.

Q & A

What makes measles so contagious?

Measles is highly contagious because it is an airborne virus that spreads through tiny liquid particles released when an infected person sneezes or coughs. These particles can remain in the air for up to two hours, and touching contaminated surfaces or breathing in the air can lead to infection.

How does the measles virus enter human cells?

The measles virus enters human cells through its surface protein called hemagglutinin (H-protein), which binds to specific receptors such as CD46, CD150 (SLAM), or nectin 4 on the surface of target cells. Once bound, another protein, the fusion (F) protein, helps the virus fuse with the cell membrane and enter the cell.

What is the incubation period for measles?

The incubation period for measles is typically 10 to 14 days from the time the virus enters the body to the onset of symptoms.

What are the key symptoms during the prodromal phase of measles?

The prodromal phase of measles lasts around three days and starts with a high fever, cough, conjunctivitis (inflammation and redness of the eye), and carisa (swelling in the nasal mucous membrane).

What are Koplik spots and when do they appear?

Koplik spots are small, white spots on the inside of the cheeks, opposite the molars, and appear one to two days after the initial prodromal symptoms. They are a distinctive sign of measles infection.

How does the measles rash develop?

The measles rash, called exanthem, begins as red, blotchy, maculopapular patches that spread from the head (cephalocaudal direction) down to the extremities. The rash typically fades after about four days.

What are some potential complications of measles?

Measles can lead to severe complications such as pneumonia, diarrhea, encephalitis (brain inflammation), and bacterial superinfections. These complications are particularly severe for young children, who have the highest mortality rates during measles outbreaks.

What is subacute sclerosing panencephalitis (SSPE) and how is it related to measles?

Subacute sclerosing panencephalitis (SSPE) is a rare but severe complication that can develop 7 to 10 years after a measles infection. It involves chronic inflammation of the brain, possibly caused by a persistent measles virus infection or abnormal immune response. SSPE leads to symptoms such as mood changes, seizures, coma, and can result in death if left untreated.

How is measles diagnosed?

Measles is diagnosed through serological testing, which involves looking for measles antibodies in the blood. It is most likely to occur in unvaccinated individuals.

What is the role of the measles vaccine, and how effective is it?

The measles vaccine is a live attenuated immunization given at ages 12-15 months and again between 4-6 years. It has an impressive 95% efficacy rate, meaning that it prevents 95 out of 100 measles cases in unvaccinated individuals.