export_sst viruses i Flashcards
What causes non-infectious skin lesions in viral infections?
Immune response
What causes infectious skin lesions in viral infections?
Viral replication
Papilloma
Benign growth on the surface of the skin or mucous membrane
Macule
Small discolored patch of skin that forms an area distinct from the normal surrounding surface
Papule
Small, circumscribed, raised portion of the skin
Vesicle
Small pouch on the surface of the skin filled with clear liquid
Pustule
Small, circumscribed, raised portion of the skin filled with purulent material
Warts general features
Hyperkeratotic
Usually painless
Koilocytes may be found
Lump/nodule/papilloma
Caused by HPV
Verruca valgaris
Cutaneous warts
Common, can be in groups
Most commonly on hands, elbows, and knees
Verruca plantaris
Flat, flushed cutaneous warts
Found on the feet
Verruca plana
Less common cutaneous wart
Flat
Most common in children, on the face, on the chest
HPV virus family features
Papovaviridae
Non-enveloped
dsDNA
Replication associated with differentiation status of tissue
HPV virulence factors
HPV E7
HPV E6
HPV E7
Inhibits Rb
HPV E6
Inhibits p53
HPV serotypes that cause common cutaneous warts
HPV 2
HPV 3
HPV 10
HPV serotypes that cause plantar warts
HPV 1
HPV 4
Diagnose warts
Clinical appearance
Hyperkeratosis and Koilodal cells
Wart removal
Cryotherapy
Cytotoxic chemicals
Surgical removal
Molluscum contagiosum presentation
Painless, p early, u mbilicated n odules
Molluscum contagiosum virus family features
Poxviridae family
dsDNA genome
Replicates in cytoplasm
Molluscum contagiosum transmission and treatment
Direct contact (sexual activity) or fomite transmission Often resolves on its own, but removal also through surgery and cryotherapy
Herpes labialis presentation
Cold sores, on mouth
Herpes labialis causative agent
HSV
HSV primary infection
Can be asymptomatic
Can be a normal cold sore
Can have widespread lesions inside (primary herpetic gingivostomatitis) and around mouth
Herpes simplex keratitis
Leading cause of blindness in the U.S.
Initially causes conjunctivitis
Recurrent disease leads to corneal opacity
Herpes simplex encephalitis
Most common cause of infectious encephalitis in the U.S.
High mortality rate
Survivors often have neurologic dysfunction
Herpetic whitlow
HSV lesion on fingers (also toes)
HSV virus family and features
Herpesviridae
Enveloped
dsDNA
Latent and lytic phases of life cycle
What form is the HSV virus in when it is causing a cold sore?
Lytic phase
Where is the HSV found in the latent phase?
Neurons
Which serotype of HSV is more commonly associated with oral lesions?
HSV-1
Treatment for HSV
Acyclovir
Acyclovir mechanism of action
Inhibits viral DNA polymerase
Chickenpox causative agent
Varicella-zoster virus (VZV)
Chicken pox lesion evolution
Vesicles
Pustules
Scabs
Where are chicken pox lesions usually not found?
Soles of feet
Palms of hands
Neonatal chicken pox
Pregnant mother infected within first 20 weeks - low birth weight, skin scarring
Infection late/right after birth results in disseminated infections, much more serious
Zoster/Shingles features
Elderly/immunosupproessed
Paresthesia prodrome
Vesicular lesions are unilateral
Fever and malaise
Postherpetic neuralgia
Postherpetic neuralgia
Pain at site of lesions for months after lesion resolution
Zoster/Shingles cause
VZV reactivation
What is the pattern of zoster/shingles in the affected individual?
Follows one dermatome
VZV virus family and features
Herpesviridae
Enveloped
dsDNA
Latent infection
Diagnose VZV
Based on clinical presentation of lesions
Tzanck smear
Prevent VZV
Varicella vaccine
Zoster vaccine
Varicella vaccine features
Live attenuated
Combined with MMR
One dose at 12-15 months, second at 4-6 years
Used to prevent primary infection
Zoster vaccine features
Same live attenuated strain as varicella vaccine (higher titer)
Used to protect from VZV reactivation
Treat VZV
Antiherpetic drugs (acyclovir) in severe cases VZV is not as sensitive to these drugs as HSV
