How are HSV, VZV, and Variola spread?
HSV: direct contact
VZV: respiratory route
variola: respiratory or contact
Cowdry’s Type A Acidophilic intranuclear inclusion bodies
Tzanck Smear
see multinucleate giant cells
Where does the HSV replicate?
in vesicular lesions
What is the immune response against HSV?
ABs against glycoproteins to neutralize/limit the spread of EC virus
CMI: essential for controlling & resolving the infection
mutlinucleate giant cells
What is the pathogenesis of VZV?
replication in respiratory tract
viremia: blood & lymph to reticuloendothelial cells
skin lesions on entire body: dermal vesciulopapular rash, develops in successive crops
becomes latent in DR or CN ganglia
How is HSV treated?
1st herpes episode: acyclovir (oral or topical)
What is the incubation period of VZV?
14 days
dew drop on rose petal
successive crops with lesions in all different stages
unilateral lesions in a dermatome
Herpes Zoster
postherpetic neuralgia (chronic pain syndrome)
can develop from herpes zoster
How is VZV treated?
vaccine: live, attenuated
adults/immunocomp: acyclovir
What is the largest, most complex dsDNA virus?
variola/small pox
Guarnieri bodies
What is special about the variola virus compared to other DNA viruses?
It replicates in the cytoplasm instead of the nucleus
What are the 2 variola viruses that infect humans?
orthopox virus (small pox)
molluscipox vireus (molluscum contagiousum)
wart-like growth in clusters
molluscum contagiousum
hemorrhage of small BVs
orthopox virus (small pox)
rash starts on face/extremities and spreads inward
small pox
Which human virus of variola can lead to death?
orthopoxvirus: can lead to death
molluscipoxvirus: benign/self-limiting
slapped-cheek rash
parvovirus B19
ssRNA (-) sense virus
How is measles transmitted?
respiratory droplets
contagious 1-2 days before and up to 4 days after the rash
90% attack rate, 100% symptomatic
What are the virulence factors of measles?
HN: viral attachment
F: fusion of cells/viral entry
M: inside viral envelope; important in viral assembly
cough, coryza, conjuctivitis, fever, Kaplik’s spots
What are some complications of measles?
bacterial superinfection
post-infectious meningo-encephalitis
progressive infectious encephalitis
giant cell PNA w/rash
ssRNA (-) sense virus
What is the clinical presentation of Rubeola Virus?
Cough, Coryza, Conjuctivitis, Kalik’s spots, maculopapular rash that lasts for 5 days
cough, coryza, conjuctivitis, kaplik’s spots, maculopap rash
rubeola vrius
How is Rubeola Virus spread?
respiratory droplets
contagious 1-2 days before and up to 4 days after rash
peaks in winter & spring
Explain the pathogenesis of Rubeola Virus
1. HN: viral attachment
2. F: fusion of cells/viral entry
3. M: important in viral assembly inside envelope
4. 7-21 day incubation
5. local replication in respiratory epithelium
6. lymph spread
7. viremia
5. systemic infection
6. immune response/maculopap rash
7. complications: PNA, post-infectious encephalitis, subacute sclerosing panencephalopathy
What virus does not replicate in the respiratory epithelium?
What are some complications of Rubeola Virus?
bact. superinfection i.e. PNA
post-infectious meningo-encephalitis
SSPE caused by defective virus assembly
progressive infectous enceph (2-10yrs after primary infection)
giant cell PNA w/rash
When is the MMR vaccine administered?
12-15 months and a booster during elementary school
What age group is most affected by Parvovirus B19?
ages 4-15
How is parvovirus B19 spread?
resp secretions and parenteral transmission
What virus replicates in mitotically active cells of erythyroid origin?
parvovirus B19
slapped-cheek rash
parvovirus B19
What are the 2 phases in fifth disease?
1. flu-like Sxs
2. slapped-cheek rash, arthralgias
Who is at risk for complications from parvovirus B19?
chronic anemia: risk for aplastic crisis
seronegative women: at risk for fetal loss
immunocomp: progressive BM suppression
naked DNA virus
parvovirus B19
How is roseola spread?
saliva and respiratory aerosols
In what age group is Roseola most common?
<4 years old
What is the clinical presentation of Roseola (Human Herpesvirus-6)?
high fever, maculopapular rash seen in AIDS patients and children <4
syncytia formation/multinucleate giant cells
rubeola virus
ssDNA virus
parvovirus B19
Categories: Microbiology