MMR (RNA Viruses) Flashcards
(46 cards)
How is the measles virus different from the other Paramyxoviruses?
It lacks a neuraminidase activity (has an H protein rather than an HN) and it forms intracellular inclusion bodies.
What phase of life is Measles associated with and how is it spread?
Childhood; respiratory route
What is the latent period of Measles?
10-14 days
What are the symptoms of Measles?
2-3 prodrome of fever, cough, and conjunctivitis followed by a characteristic maculopapular rash
What does the rash coincide with in Measles?
T-Cell response (CD8) and virus clearance
What is the clinical definition of Measles?
Generalized rash (>3 days), Temperature >38.3 C, Cough, +/- Rhinorrhea, +/- conjunctivitis
Where is replication of Measles initially limited to? Where does it spread to after that?
Initially in trachea and bronchial epithelium, after 2-4 days to lymph nodes
What does replication of Measles in lymphoid tissue result in?
The appearance of lymphoid or reticuloendothelial giant cells (Warthin-Finkeldey Cells)
When do symptoms occur in Measles?
Soon after the onset of viremia
When is the patient infectious in Measles?
1-2 days BEFORE symptoms occur (10-20 days post exposure)
What are the two characteristic symptoms of Measles?
Maculopapular (morbilliform) rash and Koplik spots
What is the adverse effect that occurs during a Measles virus infection that will lead to suppression of delayed type HS skin test responses? What else is impaired?
Immunosuppression; Ab and cellular immune responses to new antigens
According to the timeframe given in the handout, what is the first Measles complication and when does it occur?
Acute disseminated encephalomyelitis (ADEM) or postinfectious encephalomyelitis (PIE); Occurs about 10-30 days after an infection.
What is ADEM/PIE? (no…. not just what does it stand for…) What does it do to you?
It is a autoimmune demyelinating disease associated with an immune response to myelin basic protein. Induction is unknown and not restricted to measles. Good prognosis
According to the timeframe in the handout, what is the second Measles complication and when does it occur?
Measles Inclusion Body Encephalitis (MIBE); occurs 1-9 months post infection
According to the timeframe in the handout, what is the third Measles complication and when does it occur?
Subacute Sclerosing Panencephaliits (SSPE); occurs 3-12 years after (more detailed chart says 6-10 years)
What are MIBE and SSPE resultant from?
Result from the establishment of persistent infections of the brain; mechanism of entry to CNS unknown, are fatal within years
What is the main method of prevention of Measles?
MMR; live-attenuated measles vaccine is effective and safe; administered in the trivalent (with mumps and rubella) at 12-15 mo. and again at 4-6 years
Why are both mumps and measles so easy to vaccinate against?
They both are antigenically stable monotype viruses; so once someone recovers they are immune for life
Are there different strains of measles and mumps? Does it matter?
Yes there are, defined by AA differences in H and HN proteins but it doesn’t matter because neutralizing Ab to one protects against all known strains
Why are Measles and Mumps good candidates for “eradication”
Only one serotype, most cases clinically identifiable, no animal reservoir, and “herd immunity” (98%) can be achieved with vaccine
What are the factors limiting the MMR vaccine?
Pregnancy and Immune status
What genus is Measles a part of?
morbillivirus genus of Paramyxoviridae
What genus is Mumps a part of?
Rubalavirus genus of parayxoviridae
