Herpes simplex virus

Question 1

definition of herpes simplex virus

Answer 1

disease from HSV1 or HSV2 infection

Question 2

aetiology of HSV

Answer 2

an a-herpes virus with dsDNA

transmitted bia close contact with an individual shedding the virus eg kissing/sex

Question 3

pathology of HSV

Answer 3

multiply in epithelial cells of mucosal surface = vesicles/ulcers

follwoing primary viral infection, virus becomes dormant (classically in trigeminal or sacral root ganglia)

reactivation can occur in response to physical or emotional stress or immunosuppression

virus causes cytolysis of infected epithelial cells and vesical formation

get disseminated infection if impaired T cell immunity - pneumonitis, hepatitis, colitis

Question 4

epidemiology of HSV

Answer 4

90% adults sero positibe for HSV1 by 30yrs

35% adults >60 yrs seropositive for HSV2

>1/3 world pop has recurrent HSV infections

HSV1 infection in ⅔ of world’s population (~3.7 billion <50yrs), and HSV2 in ~11% (~400 million)

Question 5

sx of HSV1

Answer 5

primary infection often asymptomatic

sublinical or sensory nerve (tinglining) prodrome, then vesicles, then shallow ulcers

systemic symptoms - fever, malaise, lymphadenopathy

heals in 8-12d

pharyngitis

gingivostomatis - may make eating painful - fever, sore throat, tender oropharyngeal vesicles

keratoconjunctivitis - corneal dendritic ulcers

herpetic whitlow - innoculation of virus into a finger through break in skin (distal phalynx)

recurrent infection/reactivation less severe unless immunocompromised (herpes labilais/cold sore) - prodrome (6hr) - perioral tingling and burning. Vesicles appear (48h duration) ulcerate and crust over. complete healing in 8-10days

HSV encephalitis

secondary infection - eg HSV infection of eczematous skin - eczema herpeticum

Question 6

sx of HSV2

Answer 6

very painful blisters and rash in genital, perigenital and anal area

dysuria

fever and malaise

Question 7

HSV keratoconjunctivitis

Answer 7

epiphoria (watering eyes)

photophobia

Question 8

signs of HSV1 primary infection

Answer 8

tender cervical lymphadenopathy

erythematous, oedematous pharynx

oral ulcers filled with yellow slough (gingivostomatitis

digital blisters/pustules (herpetic whitlow)

Question 9

signs of herpes labialis

Answer 9

perioiral vesicles/ulcers/crusting

Question 10

signs of HSV2

Answer 10

maculopapular rash

vesicles and ulcers - external genitalia, anal margin, upper thighs

inguinal lymphadenopathy

pyrexia

Question 11

signs of HSV keratoconjunctivitis

Answer 11

characteristic lesion is a dendritic ulcer

may be visualised following staining with 1% flurescein

Question 12

Ix for HSV

Answer 12

usually clinical dx

vesical fluid (swab/scraping) - electron microscopy, PCR, direct immunofluorescence, growth of virus in tissue culture

can PCR CSF

serology

dx of HSV encephalitis

confirmation needed in encephalitis, keratoconjunctivitis or immunosuppression

Question 13

summarise herpes encephalitis

Answer 13

most common treatable viral encephalitis

transfer of virus from a peripheral site to brain through neuronal transmission

prodrome - fever, malaise, headache, nausea

encephalopathy - general/focal signs of cerebral dysfunction - psychiatric problems, seizure, focal neurology (temporal involvement in 60%), memory loss

in HSV1 immunocompetent pts