herpes viruses

Question 1

why are viruses dangerous to me

Answer 1

transmitted by saliva in asymptomatic and symptomatic individuals

Question 2

herpesviridae virology

Answer 2

-family herpesviridae
enveloped
-double stranded DNA
-150kbp
-lytic infection-replicates in cytoplasm and causes cell death by bursting
-latent infection- can reactivate symptomatically or asymptoaticlaly

Question 3

how does latency work

Answer 3

Causes tissue damage with vesicles full of fluid with active virus in them. Once the body fights of the vrisus it will move down the sensory neurons to the spinal ganglia. Hsv1 tends to be the trigeminal ganglia and hsv2 is tends to be the scaral ganglia but not strict rules. Then it wll reactive and move down the neuron to the epithelial cells and then replicate and then you get active symptoms or asymptomatic

Question 4

primary infection

Answer 4

if you have already had hsv1 you cannot get a hsv2 infection as they follow a similar immune response

Question 5

HSV epidemiology

Answer 5

Most primary infections before 5 years

HSV 1 UK seroprevalence up to 50-70%
HSV 2 UK seroprevelance ~10% ( more in usa 25%)

Oral - close social contact – kissing, nurseries..
Genital – sexual contact

Question 6

what is seroprevalence

Answer 6

Seroprevalence refers to combined HSV 1 and/or 2, Newer HSV-1 data suggests lower seroprevalence. Seroprevalence varies in different countries or different groups in the same country (e.g. HSV-2 seroprevalence 25% in USA)

Question 7

hsv primary oral herpes

Answer 7

primary infection with HSV1 OR HSV usually asymptomatic and cause cause sever gingivostomatitis - swollen lips and lesions
may require hospitalisation as dehydration or pain and child may need nasogastric feeding

Question 8

HSV oral reactivation

Answer 8

reactivation of HSV1 or HSV2 usually asymptomatic but can cause cild sores on boarder of lips- rarely intra-oral

• can be random and have non-specific triggers e.g. stress, fever,mesntration,cold
• can be itching or tingling before vesicles and lasts 5-12 days

Question 9

hsv- genital disease

Answer 9

• HSV1 and HSV2
  reactivate is usually with HSV2
• primary more sever than reactivation and cause discomfort
  reactivation can often be asymptomatic

Question 10

hsv mian complications

Answer 10

• Secondary bacterial infection (beaking down)
• Corneal Ulcers, risk of scarring, loss of vision
• Meningitis, self limited, usually HSV 2, can be recurrent (Mollaret’s meningitis)
• Herpes Simplex Encephalitis, life-threatening, usually HSV 1
• Neonatal Herpes Simplex – life threatening
• Life threatening infection in the immunocompromised- can cause liver ailue

Question 11

what is hsv- hepatic whitlow

Answer 11

thumb sucking/contact sports

Question 12

HSV -ocular infection

Answer 12

dendritic ulcer and can be sight treating

Macliver drops needed

Question 13

HSv neonatal

Answer 13

during birth process or someone who has the virus either asympomaitc or symptomatic
more risk if the mother has primary
- c-section required
- acyclovir
the baby can get a rash (dermatomes or CNSor gets multi-organ failure

Question 14

HSv-encephalitis

Answer 14

Commonest cause of viral encephalitis
70% mortality untreated
High rate of poor neurological outcome
Temporal lobe enema
Confused and fevers but can cause phycological impairment if they survive can be missed in older patients  
mimimm of 10 days treatment iv acyclovir

Question 15

diagnosis

Answer 15

direct viral detection
PCR
-lesion swab
cerebrospinal fluid -not common

Question 16

treatment

Answer 16

Aciclovir
Needs activated by a viral enzyme – thymidine kinase(only active in virus cells) – so specific for infected cells
Poor oral bioavailability, 5 x per day dosing

Valaciclovir
Prodrug of aciclovir
Good oral bioavailability, but more expensive
Can get kidney issues with it

Question 17

VZV-primary infection chicken pox

Answer 17

Prodrome of fever before rash is common
Centipetal distribution- head,no arms
Macules       Papules       Vesicles       Pustules
All stages can be seen at the same time
Crops of lesions at different stages
More severe in adults
Oral vesicles can occur before those elsewhere and can be extremely painful.
range of severity

Question 18

Centripetal distrubution

Answer 18

Centripetal distrubution – vesicles start on trunk and are more numerous on trunk than limbs.

Question 19

chicken pox epidemiology

Answer 19

UK > 90% seroprevelance (naturally immune)
Outbreaks mainly in winter/spring
Attack rate for household contacts is 90%
Peak age is now <5 years
Respiratory transmission or direct contact
Incubation period 8-21 days (average 14 days)
Infectious from 2 days before rash to full crusting of vesicles
- fully crusting takes average of 5 days from rash onset

Question 20

VZV reactivation zoster shingles

Answer 20

dermatomal- never crosses dermatomes and doesn’t cross halves of bodies - in more than one dear,tome it could be immunocompromised and could be HIV

Question 21

eye shingles

Answer 21

ophthalmic zoster
affecting trinomial nerve
- ocular complications particular likely if nasocillary branch is involved
lesions on side of nose
post hepatic neuralgia- can last long tie cannot sleep

Question 22

diagnosis

Answer 22

clinical
direct viral detection
PCR-lesion swab/cerebrospinal fluid