Herpes Viruses Flashcards
(36 cards)
What herpes viruses are there?
Herpes 1, 2, 3, 4, 5, 6, and 8
What is herpes virus 1 and 2?
Herpes simplex virus 1 and 2 (HSV1, HSV2)
What is herpes virus 3?
Varicella zoster virus
What is herpes virus 4?
Epstein-Barr virus (EBV)
What is herpesvirus 5?
Cytomegalovirus (CMV)
Which is more common, HSV1 or HSV2?
HSV1 - 2/3 of world’s population are infected.
HSV2 - around 11% of world’s population
Explain pathology of HSV.
Viruses multiple in epithelial cells of mucosal surface producing vesicles or ulcers.
There is a lifelong latent infection when virus enters sensory neurons at infection site.
They can then reactivate, replicate and infect surrounding tissue.
When might disseminated infection happen in HSV?
If there is impaired T cell immunity leading to pneumonitis, hepatitis and colitis.
Presentation of primary HSV infection.
Subclinical or sensory nerve tingling
Vesicles and shallow ulcers
Systemic features might occurs such as fever, malaise and lymphadenopathy.
How long does it take for primary HSV infection to heal?
8-12 days
Where might HSV infect? (Anatomy-wise)
Herpes labialis - cold sores at lip border (HSV1)
Genital herpes (HSV2)
Gingivostomatitis
Keratoconjunctivitis with corneal dendritic ulcers. (Avoid steroids in this)
Herpetic whitlow - painful vesicles on distal phalanx
Herpes encephalitis
Explain herpes encephalitis.
This is the most treatable encephalitis.
There is transfer of virus from peripheral site to brain via neuronal transmission.
This is predominantly in HSV1 and generally affects temporal lobe.
Presentation of herpes encephalitis.
Fever, malaise, headache and nausea.
There is then encephalopathy involving general and focal neurological signs and dysfunction.
Psychiatric symptoms
Seizures
Memory loss
Secondary infection of HSV.
HSV infection of eczematous skin like eczema herpeticum
Diagnosis of HSV.
Clinical diagnosis.
Confirmation is needed if there is encephalitis, keratoconjunctivitis or immunosuppression.
This is then done with viral PCR of CSF, swab or vesicle scraping.
Culture, immunofluorescence and serology can also be done.
Treatment of HSV.
Aciclovir - will reduce symptoms and viral shedding. It will however not prevent latent infection.
In herpes encephalitis empirical IV aciclovir should be done.
What is Varicella zoster virus (VZV)?
Primary infection transmitted by respiratory droplets.
The incubation period is 14-21 days.
Pathology of VZV.
It invades the respiratory mucosa and replicates in lymph nodes.
It then disseminates via mononuclear cells to infect skin epithelial cells.
The virus is then contained in vesicles = chicken pox.
The virus then lies dormant in sensory nerve roots.
What is dermatomal reactivation of dormant VZV called?
Shingles
Presentation of chicken pox.
1-2 days of fever, malaise, headache and abdo pain.
Then the rash comes which is a pruritic, erythematous macules going to vesicles.
Crust develops in 48h from onset of rash.
Patient is then infectious 1-2 days prior to onset of symptoms and 5 days post rash development.
Complications of chicken pox.
This is usually only the case in immunosuppresion.
Encephalitis with cerebellar ataxia
VZV pneumonia
Transverse myelitis
Pericarditis
Purpura fulminans/DIC
Presentation of shingles.
Painful hyperaesthetic area in one dermatome.
There is then a macular rash going vesicular in one dermatome.
The patient is infectious until scabs appear.
There is also a risk of causing chicken pox in a non-immune contact.
This means that someone with shingles can infect a non-immune causing them to have chicken pox.
Complications of shingles.
Disseminated infection
Post-herpetic neuralgia
Ramsay-Hunt syndrome.
Diagnosis of VZV.
Clinical diagnosis unless the patient is immunosuppressed.
Then you go for viral PCR, culture and immunofluorescence.
