Herpes Simplex and Varicella Zoster Flashcards Preview

Medical Microbiology > Herpes Simplex and Varicella Zoster > Flashcards

Flashcards in Herpes Simplex and Varicella Zoster Deck (22):
1

Herpes Viruses

HSV1 HSV2 VZV EBV CMV HHV6 HHV7

2

Common characteristics of herpes viruses

Large, enveloped dsDNA viruses, very ubiquitous, chronic/latent infection follows acute infection, reactivations are common, mostly transmitted during asymptomatic shedding, mostly transmitted by close contact

3

Which herpes virus isn't transmitted via close contact and asymptomatic shedding?

Varicella

4

Herpes Viruses Mechanisms of Injury

Direct Cell damage, immune reactions, malignant transformation, immunosuppression and opportunistic infections

5

Life cycle of the herpes viruses

Attachment and penetration by fusion, immediate early protein synthesis regulates viral replication, early protein synthesis replicates the genome, late protein synthesis mediates the assembly of viral particles, release, cell to cell spread.

6

Acyclovir

Herpes DNA polymerase inhibitor that requires phosphorylation by a viral thymidine kinase.

7

HSV 1 and 2 pathogenesis

Enters via abraded skin and mucosa, create lesions at the site of entry and remain latent in the sensory ganglia (geniculate and dorsal root). Reactivates with intercurrent illness, UV light, stress and immunosuppression.

8

HSV pathology

Giant cells with intranuclear inclusions: Tzanck Test

9

What infections are associated with HSV-1/HSV-2?

HSV-1 more commonly associated with oral infection, HSV-2 more commonly associated with genital infeciton

10

How does HSV spread?

Close contact

11

What does HSV cause?

Crops of painful small blisters and ulcers. Asymptomatic shedding

12

HSV esophagitis

Happens, so does HSV encephalitis

13

Diagnosis of HSV

Viral culture (but not good for CSF), DFA of skin lesions, PCR for CSF, Tzanck smear (older test)

14

What is better than oral acyclovir?

Valacyclovir (prodrug that is converted to acyclovir) is absorbed more efficiently.

15

Adverse effects of acyclovir?

Rare kidney dysfunction, resistance due to mutations in viral thymidine kinase or DNA polymerase

16

How to treat acyclovir resistant HSV?

Foscarnet, an inorganic pyrophosphate that inhibits viral DNA polymerase, iv administration only, can be nephotoxic and screw with calcium and phosphate levels.

17

Valacyclovir prophylaxis

Can be used to decrease shedding in genital secretions, can prevent HSV complications

18

Varicella Pathogenesis

Infection of mucosa of upper respiratory tract, viral replication in regional lymph nodes, primary viremia, viral replication in liver and spleen, secondary viremia, fever and contagion, infection of skin and appearance of vesicular rash. This occurs 12-15 days after initial infection.

19

Varicella Zoster virus

Chickenpox, latency in the DRG/sensory ganglia, reactivation=zoster (shingles). Highly contagious, spread by respiratory droplets and aerosols, and by contact.

20

Complication of shingles

post-herpetic neuralgia

21

Treatment of shingles

Acyclovir and valacyclovir

22

vaccine for VZV?

Live attenuated vaccine