Viral infections

Question 1

What are herpes viruses and what kinds are there?

Answer 1

DNA viruses

Herpes simplex virus = herpes genitalis HSV2, herpes labialis HSV1, herpetic keratoconjunctivitis HSV1 of eye)

Varicella-zoster virus (VZV) = 1) chicken box (varicella), 2) shingles (herpes zoster = latent varicella in dorsal root ganglia, unilateral neuropathic pain

cytomegalovirus (CMV) = asymptomatic in immuno-competent patient, cause disease in immunocompromised (retinitis, esophagitis, colitis)

Question 2

What are the drugs used to treat herpes virus?

Answer 2

Foscarnet = nephrotoxic, not routine

Aciclovir = not well absorbed through skin or gut (poor + erratic)

Valciclovir (prodrug of aciclovir) and famciclovir = well absorbed orally, less frequent dosing compared to aciclovir

Ganciclovir (IV) = used in immunocompromised patients, dose dependent bone marrow suppression

Valganciclovir (prodrug of ganciclovir) (oral form of ganciclovir) = well absorbed orally, as effective as IV

Question 3

What is a primary herpes illness?

Answer 3

Occurs in childhood, inflammation/herpes in the gums

Herpes typically will start where the first infection/exposure was

Question 4

How is mild herpes recurrence treated?

Answer 4

Topical aciclovir

Question 5

How is severe herpes recurrence treated?

Answer 5

Oral aciclovir (many doses)

Famciclovir, valciclovir (less doses than aciclovir)

Question 6

What are the suppressive therapies for herpes virus?

Answer 6

oral aciclovir, valciclovir (6 months)

Question 7

How are genital herpes treated?

Answer 7

Oral aciclovir, famciclovir, valciclovir

Lower dose for initial infection

Higher dose episodic treatment recurrence

same drugs for suppressive therapies = 6 months

Question 8

Are children typically treated for varicella?

Answer 8

No, only neonates and adults (primarily) are treated due to inc risk of complications of varicella and severe disease

Question 9

When should adults be treated for varicella?

Answer 9

treat within 36 hours after rash onset

Treat pregnant women within 72 hrs after rash onset

Question 10

How do you treat varicella in adults?

Answer 10

oral aciclovir, famciclovir, valciclovir = if they havent had varicella before and are immunocompetent

Question 11

How is varicella treated in immuno-compromised or complicated varicella cases?

Answer 11

IV aciclovir irrespective of rash duration

For neonates, preg, HIV, if varicella is in brain, liver, lung

Question 12

What is shingles?

Answer 12

reactivation of herpes zoster later in life, presents as rash blisters w/ a dermatomal distribution on erythematous base

Question 13

What is the antiviral treatment for shingles?

Answer 13

Immunocompetent (w/i 72 hrs) = famciclovir 8hrly, valaciclovir 8hrly, aciclovir 5*daily

Immunocompromised = admit to hospital, IV aciclovir

Will reduce = pain, duration of rash, viral shedding, ophthalmic complication

Question 14

What are the types of herpes keratitis?

Answer 14

Epithelial keratitis

Stromal keratitis = corneal scarring and loss of vision

Question 15

How is herpes keratitis treated?

Answer 15

Aciclovir eye ointment topically 5*/day

Question 16

How is herpes zoster keratitis treated?

Answer 16

Topical is not effective

Oral for immunocompetent

IV for immunocompromised (acyclovir)

Question 17

How is cytomegalovirus treated?

Answer 17

Immunocompetent = self-limiting (mono or hepatitis like syndrome)

Immunocompromised = valganciclovir, ganciclovir, foscarnet (immunocompetent), cidofovir (immunocompetent)

Question 18

How is influenza treated?

Answer 18

Treat with neuraminidase inhibitors = oseltamivir or zanamivir

Antiviral therapy recommended for preg women after risk/benefit discussion = high risk of poor outcome

Question 19

Give a general summary of herpes treatment

Answer 19

Treat as soon as possible

Herpes simplex = topical

Herpes zoster = systemic (oral, IV for high risk)

Acicolvir not ideal = freq dosing, erratically absorbed

Question 20

Discuss Hep A

Answer 20

Contracted via = uncooked/contaminated food/water or direct contact w/ infected person

Self-limiting, no specific treatment

Question 21

Discuss Hep B

Answer 21

Contracted via = bodily fluids, mother to child, unprotected sex

No cure (can be self-limiting otherwise chronic illness), low chance of chronic liver disease/cancer (except high chance for foetus)

Treatments (supress viral load, inactivate) = nucleotide/nucleoside analogues, pegylated interferon

Question 22

Discuss Hep C

Answer 22

Contracted via = unsafe injection practice, infected blood/organ transfer, unprotected sex

Can survive outside body for long time, no natural immunity

Cause chronic infection, liver cirrhosis

Question 23

What drugs are used to suppress Hep B viral load?

Answer 23

Entecavir, tenofovir

Question 24

Can hep C be cured?

Answer 24

Yes, can be cured using directly acting antiviral drugs

Protease inhibitors, nucleotide polymerase inhibitors, non-nucleotide polymerase inhibitors, NS5A inhibitors

But no immunity after previous exposure

Question 25

What is the post treatment monitoring for Hep C

Answer 25

W/ no cirrhosis = no monitoring

W/ cirrhosis = monitoring/management of cirrhosis, surveillance for hepatocellular carcinoma, gastro-oesophageal varicies

Question 26

Explain the PEP for Hep B

Answer 26

W/ hx of immunity/vaccine = no further follow up

non-immune = vaccination and follow up after 6 months

Non-immune, source has chronic hep B = single dose of HBIF w/in 72 hrs, hep B immunisation commenced

Question 27

Explain the PEP for Hep C

Answer 27

Potential risk (shared needles, needlestick injury, men who have sex with men) = baseline follow up testing

Refer if Hep C seroconversion detected, inform about acute hep C symptoms