Lec48 Infectious disease of skin Flashcards
What causes warts?
HPV
What types of dermo findings for HPV1 and 2?
- palmoplantar [palms and soles] and common warts
What type of dermo findings for HPV6 and 11?
- genital warts
What are effects of HPV16/18?
cervical/genital cancer
What is pathogenesis of HPV infection?
- spread by direct contact with broken skin –> virus enters basal –> induces cellular proliferation
What is appearance of HPV warts?
- verrucuous papule/plaque with thrombosed capillaries
- thrombosed capillaries show as black dots
- elevated, rough skin
How do you distinguish corn/callous from wart?
wart ablates skin lines
corn/callous does not
What is typical therapy for warts?
- mechanical destruction –> cryotherapy [freezing] or salicylic acid plasters
- induce immune response: inject candida to cause local immune response
What is sign of HSV derm?
crop of vesicles on erythematous base
Which type of herpes primarily responsible for labial herpes? genital herpes?
HSV1 = labial [lips] HSV2 = genital
What is pathogenesis of HSV? transmission?
- virus contacts skin –> replicates in dermis/erpidermis –> infects and latent in trigeminal or sacral sensory ganglion –> recurs focally where nerve innervates
transmission by direct contact –> contagious until crusted
What triggers HSV reinfection?
stress, UV light, fever
What is manifestation of HSV prodrome?
tenderness/burning –> then skin pressentation/blister
What happens if HSV near eye?
can lead to eye infection –> keratitis/blindness
When do you get eczema herpeticum?
- spreads along contiguous skin due to compromised barrier [eczema, burn, etc]
What is disseminated HSV? who gets it?
- spreads more widely than one area, can have more scattered individual lesions
- occurs in immunocompromised
Where does ZVZ stay latent?
sensory nerve root
What is life cycle involved in shingles? clinical signs?
- dermatomal rash, does not cross midline [vs HSV crosses midline]
- can have post-herpetic nerualgia in affected sensory nerve
- lytic life cycle
Who gets disseminated VZV? sign?
- in immunocompromised
- have dermatomal rash + individual lesions via hematogenous spread
How is VZV transmitted?
- contagious –> by contact
How do you diagnose HSV/VZV?
- tzanck spear [only tells you part of herpes family]
- DFA –> anti HSV/VZV antibodies
- viral culture
- PCR
What is treatment for HSV/VZV?
- acyclovir, valganciclovir, famciclovir
- foscarnet [for resistant]
What can cause mononucleosis?
- usually EBV [human herpesvirus 4]
- also could be CMV, toxoplasmosis rarely
What are clinical features of infectious mono?
- triad: pharyngitis, fever, lymphadenopathy [esp cervical]
- periorbital edema
- hepatosplenomegaly
- can have rash beginning on trunk with later extension to face
- 90% have hypersensitivity skin rxn to ampicillin/amoxicillin
How do you diagnose mono?
- > 50% lymphocytes, > 10% LFTs
- monospot test: detects IgM antibodies in wk 2]
How do you treat mono?
- coritcosteroid in case of complications
- otherwise supportive
What causes erythema infectiosum? Other names?
other names: fifth disease, slapped cheek disease
- due to human parvovirus B19
What type of properties human parvovirus B19 [strandedness, DNA or RNA]?
- single strand
- DNA
What are clinical features of erythema infectiosum?
- prodrome: fever, headache, myalgia
- exanthem: bright red macular erythema [= bright red patches esp on face]
- may have arthralgia or arthritis
What is pathogenesis of erythema infectiosum?
- initially infect respiratory –> B19 viremia with decrease in reticulocytes –> viremia ends with IgM Ab –> IgG appears with rash and arthralgia after a few days