Viral Infections Flashcards
HIV: Describe the 4 phases in its natural history
1- Early SEROCONVERSION (3 weeks)
- Flu-like illness with fever
- Maculopapular rash
- Lymphadenopathy, mouth ulcers
2- Early ASYMPTOMATIC (months)
- CD4 > 0.5 (normal)
- Well
- +- mild thrombocytopaenia
3- Intermediate (5 years)
- CD4 <0.5
- Begin to get opoortunistic infections/ malignancies
- Less severe illnesses - may still not be recognised as HIV.
4- Late/ AIDS (10 years)
- CD4 < 0.2
- AIDS-defining illnesses
- Cytopaenias
HIV: What are ‘AIDS-defining’ illnesses?
In setting of proven HIV:
INFECTIONS
- Cryptococcus
- Cerebral toxoplasmosis (ring enhancing brain lesion)
- PJP
- TB
- Cryptosporidial diarrhoea
- Invasive candidiasis
- MAC
- CMV retinopathy
etc.
MALIGNANCIES
- Kaposi sarcoma
- NHL
- Cerebral lymphoma
+ Dementia
At what CD4 count do invasive/ AIDS-defining illnesses typically occur:
CD4 <0.2 x 10 9
Exception: bacterial pneumonia and TB, which can occur in intermediate phase
What is the likely diagnosis in HIV patient?
PCP
Pneumocystis jiroveci- fungal.
AIDS-defining
Non-specific, bilateral pulmonary infiltrates
Interstitial or alveolar
Many HIV patients are on Prophylactic Bactrim (almost 100% effective)
What is the likely diagnosis in HIV patient?
Kaposi sarcoma
AIDS-defining
Can occur in intermediate phase/ CD4 >0.2
Skin and mucous membranes
HIV: What is the utility of:
- CD4 count
- Viral load (RNA)
CD4 count
- Degree of immunosuppression
- Susceptible to infection/malignancy <0.5, and AIDS-defining illness <0.2
Viral Load (RNA)
- Infectiousness
–> ‘Undetectable’ virtually unable to spread virus
- Effectiveness of treatment
- Prognostic
List 4 important adverse effects of antiretrovirals:
Pancreatitis
Hepatitis
Renal impairment
DRESS
Antiretroviral resistance!
Drug interactions (multiple)
HIV: Diagnostic test
Antibody/antigen assay (EIA)
–> If early, can be neg. Repeat 2,4,6 weeks.
Confirmed with Western Blot
(RNA is for viral load)
Varicella Zoster: About
Spread via respiratory droplets, or fluid from chickenpox or shingles vesicles.
Chickenpox acutely.
Latent within dorsal root ganglia
Reactivates as shingles (zoster)
Complications:
–> Varicella zoster ophthalmicus
–> Ramsay-Hunt
–> Post-herpetic neuralgia
–> Disseminated incl encephalitis
–> Congenital
Treatment within 72 hours reduces blister time, neuralgia rates (partic >60):
–> ACICLOVIR 10-20/kg (800) 5x daily for 1 week.
(IV if disseminated, ophthalmicus)
Avoid babies, pregnant women
Infective until crusted (10ish days)
PEP if high-risk contacts
Shingles recurrence low (1%)
Zoster vaccine for >70 (NOT if immunosuppr)
Post-Herpetic Neuralgia:
Usually >60yo
10-20%
Pain that persists >3 months beyond rash
Severe and debilitating
Prevent with early antivirals within 72hours
Topical
–> Capsaican
Antidepressants
–> TCA: AMITRIPTYLINE, nortriptyline
–> SNIRI: Venlafaxine
Anticonvulsants
–> Gabapentin
–> Pregabalin
–> Carba, valpro
Opioids
Herpes Zoster Opthalmicus:
Ophthalmic branch of trigeminal (V1)
Can involve eye itself:
- Keratitis
- Anterior uveitis (iritis)
- Deeper spread: eg. scleritis, retinitis
Usual treatment of:
- Zoster with PO/IV aciclovir
- Keratitis with aciclovir drops
- Iritis with tropicamide
- Neuralgia prevention with neuropathic meds (more likely with ophthalmicus)
Ramsay-Hunt Syndrome:
Geniculate ganglion of CN VII (Facial)
- Hemifacial paresis (whole)
- Shingles in ipsilateral ear canal, or mouth(bucca, palate, ant 2/3 tongue)
CN VIII (vestibular) may become involved:
- Vertigo
- Hearing loss, tinnitus
Usual zoster + eye care
Audiology
Post-exposure prophylaxis (PEP) regimen Zoster:
Immunosuppressed
First week of life
Pregnant
Zoster Immunoglobulin
+
Aciclovir 7-10 day orals (10\kg) or 10/kg IV TDS if eg. neonate
Ensure vaccinated post.
