Mumps, Measles, slow

Question 0

Measles, mumps vs flu

Answer 0

All hemagglutinate
Mumps is antigenetically similar to parainfluenza

BUT
Single strand RNA -> no genetic reassortment -> no rapid antigen shifts
Flu (ortho) and paraflu (paramyxo) both local, nonviremic
Measles, mumps (paramyxo) systemic, viremic (longer incubation, lifelong immunity via IgG)

Question 1

Paramyxoviruses

Answer 1

Single (-) RNA
Helical, envelope
Must carry RNA polymerase in virion

Question 2

Mumps epidemiology

Answer 2

One serotype, only in humans ->
effective vaccine has decreased cases
lifelong immunity even after subclinical infection

Transmission = respiratory (saliva)
Infectious before and after symptoms
Incubation 18-21 days

Question 3

Mumps presentation

Answer 3

Incubation 18-21 days
Prodrome = fever, malaise, anorexia
PAROTIDITIS - unilateral or bilateral, swelling, inflamed duct
Can also have orchitis, aseptic meningitis, pancreas, ovaries
No therapy

Question 4

Mumps vaccine

Answer 4

Live attenuated
Part of MMR
Given in two low doses to minimize side effects

Effective drop in incidence when introduced (60’s)
Still epidemics in unvaccinated pockets (UK, summer camp)
Endemic in Africa

Question 5

Mumps pathogenesis

Answer 5

Respiratory transmission ->
obligatory viremia (IgG response) ->
parotid gland -> duct -> mouth ->
shed in saliva

Question 6

Measles epidemiology

Answer 6

Most contagious disease known!
Exposure (resp, tears, urine) -> almost 100% infection -> 100% symptoms
Only humans, enveloped/unstable -> requires large susceptible population

Pre-vaccine: cyclical epidemics every 3 years
(no antigenetic variation -> new births susceptible-> no herd immunity -> rapid spread)

Question 7

Measles presentation

Answer 7

Respiratory -> resp epithelium -> lymph ->
VIREMIA ->
prodrome = fever, URI, conjunctivitis = infectious shedding! ->
Koplik’s spots (red with white) on mucosa ->
rash, photophobia, fever, URI, conjunctivitis

Incubation = 14 days
No treatment

Question 8

Measles complications

Answer 8

More likely in adult, immunocompromised (partially dt immune response)
1:20 -> bacterial pneumonia
- giant cell pneumonia - can occur without rash
frequent otitis media (bact)
acute encephalitis (1-2:1000)
deaths (1-3:1000)

Question 9

Measles pathophysiology

Answer 9

Syncytia - viral membrane proteins -> fusion -> large multinucleated cells in lymphoid, resp

• damage without IgG exposure
• > giant cell pneumonia

Anergy - grows in T cells -> severely depresses cell-mediated immunity -> secondary infections -> death

Question 10

Measles in developing world

Answer 10

Higher mortality!
5-25% vs can’t regenerate immune system)
Reduced mortality from Vitamin A (best ROI for global health!)

Eradicated from US but 50-100 cases imported each year

Question 11

Measles vaccine

Answer 11

Live attenuated
Part of MMR -> given twice

Must maintain herd immunity due to high infectivity

How to eradicate? Vaccine not effective megadoses earlier?

Question 12

Slow virus overview

Answer 12

Long incubation (years) -> slow death
Can have latency -> reemerge with immune compromise
Often genetic predisposition

Ex HIV, PML, SSPE, BK nephropathy (transplant failure)

Question 13

PML

Answer 13

Progressive multifocal leukoencephalopathy
JC virus (papovavirus) -> CNS oligodendroglia ->
Immune compromise activates -> demyelination ->
Blind, dementia, coma, death

No inflammation

Question 14

SSPE

Answer 14

Subacute sclerosing pan-encephalitis
Insidious neuro/psych -> blind -> paralysis -> death

Measles and inclusion bodies in CNS, high antibody titers
Early, subclinical infection -> ? mechanism unclear, no CTL in CNS?
Can occur after vaccine but lower risk (1:million vs 1:100K)

Question 15

Prion definition

Answer 15

Disease-causing proteins - no nucleic acid
Long incubation (years) -> CNS -> spongiform encephalopathy

Ex
Scrapie (sheep)
Kuru
CJD, variant CJD
Gerstmann-Straussler-Scheinker (GSS)
fatal familial insomnia

Question 16

Scrapie

Answer 16

Prion disease of sheep
Genetic susceptibility (inbred lines)

Can infect mice (reproduce symptoms)
Resistant to UV, formaldehyde, alkylating -> not virus

Question 17

Kuru

Answer 17

Progressive prion disease
Spongiform encephalopathy - esp in cerebellum

50% mortality in New Guinea tribe
Transmission via ingestion of CNS

Question 18

CJD

Answer 18

Creutzfeld-Jacob disease
Most common prion disease in humans

Familial (fCJD) and inherited
Spontaneous/sporadic
Iatrogenic (cornea, GH, instruments)

Question 19

Variant CJD

Answer 19

aka mad cow disease

Infected cows and sheep meat -> cows ->
Humans eat contaminated meat