3.Measles Flashcards
What is the causative agent of measles?
Paramyxovirus (HA-only morphology).
How is measles transmitted?
Highly contagious via respiratory droplets or airborne spread.
What is the target cell for measles virus?
Epithelial cells of the respiratory tract.
What are the phases of measles infection?
Incubation, Prodromal, Exanthem, and Recovery phases.
What are the symptoms in the prodromal phase of measles?
Fever, Cough, Coryza, and Conjunctivitis (4 Cs).
What is the diagnostic feature seen in the oral cavity during measles?
Koplik’s spots—white lesions with red halos inside the cheeks.
What type of rash is characteristic of measles, and how does it spread?
Maculopapular rash spreading from the head to the body.
What is the mechanism behind the measles rash?
It is due to T-cell immunity attacking infected small blood vessels.
What are the acute complications of measles?
Bronchopneumonia, Encephalitis, Otitis media, UTI, and Photophobia.
What is SSPE, and when does it occur?
Subacute Sclerosing Panencephalitis (SSPE)—a fatal neurological sequela occurring 7–10 years later.
What laboratory tests are used to diagnose measles?
ELISA (antibodies), PCR (viral RNA), and Immunofluorescence Antigen Detection.
What are the components of the MMR vaccine?
Live attenuated measles virus (Schwartz and Moraten B strains).
What is the vaccination schedule for the MMR vaccine?
1st dose at 18 months, 2nd dose at 6 years.
How does vitamin A help in measles management?
Reduces complications such as pneumonia and blindness.
Why are immunocompromised patients at higher risk in measles?
Due to suppressed cell-mediated immunity, leading to opportunistic infections.
What is the primary receptor used by the measles virus?
CD46 (nucleated cells), CD150 (B/T cells), and Nectin-4 (epithelial cells).
Why is cell-mediated immunity important in measles?
It limits viral replication and prevents severe disease spread.
What is the morphology of the measles virus?
HA-only morphology for attachment to host cells.
What are Koplik’s spots?
White lesions with red halos found inside the cheeks during the prodromal phase.
What is the role of the RNA polymerase in the measles virus replication?
It facilitates replication of the viral RNA in the host cell.
What is the most contagious period of measles?
Measles is most contagious 4 days before and 4 days after the rash appears.
How is measles co-infection with HIV unique?
Measles co-infection with HIV is not associated with enanthema or exanthema.
What atypical presentation may occur in immunocompromised patients with measles?
Measles pneumonia without rash may occur in immunocompromised patients.
What is SSPE, and when does it occur?
Subacute Sclerosing Panencephalitis (SSPE) is a fatal complication occurring 7–10 years after infection.
How does measles virus replicate inside host cells?
Measles virus uses HA to bind host cell receptors, and F-protein facilitates membrane fusion. RNA polymerase drives replication and translation within the host cell.
What receptors does the measles virus use to infect host cells?
CD46 (nucleated cells), CD150 (B/T cells), and Nectin-4 (epithelial cells).
How does the measles virus spread systemically after initial infection?
The virus spreads via viremia from the respiratory tract to lymph nodes and other organs.
What causes the rash seen in measles?
Rash is due to T-cell immunity targeting infected small blood vessels.
What are the components of the MMR vaccine?
The MMR vaccine includes live attenuated measles, mumps, and rubella viruses.
What strains of the virus are used in the MMR vaccine?
Schwartz and Moraten B strains are used in the MMR vaccine.
What role does vitamin A play in measles management?
Vitamin A reduces morbidity and complications like pneumonia and blindness.
What histological findings are characteristic of measles infection?
Nuclear and cytoplasmic inclusion bodies and cytopathic effects (CPE) are characteristic histological findings.
