Other Opportunistic Infections Flashcards
What are the phases of infection of herpes viruses?
Primary infection
Latency
Reactivation
Immune compromised patients increased risk of worse primary infections and reactivation
What are the three groups of herpes viruses?
1 alpha - hsv, VZV. Primary targetcmucoepithelial with latency developing in nerve cells
- Beta - cmv, hhv 6 and 7
- Gamma - ebv, KSHV (hhv8)
What is the incidence of herpes zoster (shingles) in general population?
1.5-3 per 1000 persons per year
More frequently in those over 60 and who are immunocompromised
What is the relative risk of herpes zoster in HIV patients
15 or greater compared to age matched hiv zero negative individuals
At what CD4 count are herpes zoster outbreaks more frequent?
Cd4 <200-250
Recurrences common - up to 20-30% of cases
Effect of ARVs unclear
Risk of primary zoster infection in HIV positive population?
Uncommon due to childhood infections but can result in severe disease with visceral dissemination particularly pneumonitis
How might zoster present in HIV patients?
Usually vesicles along single deratome
In HIV can be bullous, haemorrhagic, necrotic and painful
Blisters and crusts usually last 2-3 weeks - necrotic lesions may last up to 6 weeks and heal with severe scarring
Can herpes zoster be part of IRIS?
Yes - 2-4 fold increase in risk in first few months of starting HAART. Same presentation as other HIV+ pts.
What is HZO?
Herpes zoster ophthalmicus involves ophthalmic division of trigeminal nerve
Symptoms of HZO?
Skin lesions
Involvement of conjunctiva, cornea and other eye structures can result in visual loss, keratitis, anterior uveitis, severe post heretic neuralgia, necrotising retinopathy
Presentation of disseminated herpes zoster?
Multi focal leukoencephalitis, vascularised with cerebral infarcts, myelitis, ventriculitis, optic neuritis, meningitis, focal brainstem lesions
Can herpes zoster CNS disease occur in absence of neurological lesions?
Yes
Should always be considered in patients presenting with neurological disease especially if advanced immune deficiency
How is VZV diagnosed?
Usually skin lesions diagnosed in clinical appearance
VZV antigen testing using fluoroscein-conjugated monoclonal antibodies to confirm presence of VZV antigens
Culture less sensitive but may allow for aciclovir resistance to be detected
PCR rapid and more sensitive than culture
What is found on CSF testing for VZV?
Pleocytosis
Mildly raised protein
Positive PCR for VZV DNA - absence of this does not exclude
What is the treatment of primary varicella?
IV aciclovir 5-10mg/kg TDS for 7-10 days
More prolonged treatment courses may be required until all lesions are healed
If no evidence of visceral involvement can switch to 800mg po 5x day when afebrile
In patients with high CD4 counts oral aciclovir may be considered if started within 24hrs
What is the treatment of herpes zoster?
Begin within 72hrs rash
Localised dermatomal illness 800mg 5x day
If severe cutaneous disease or disseminated infection admit to hospital for iv aciclovir 10mg/kg tds for 10-14 days
Start on ART or optimise to improve immune deficiency
How to tell if patient is resistant to aciclovir?
Failure to respond to treatment
Has been reported in patients with advanced hiv disease
IV foscarnet used instead
What is the relationship between HSV and HIV?
Genital HSV2 increases acquisition risk of HIV - doubles risk of becoming infected through sexual transmission
Coinfected individuals are more likely to transmit infection - ? High titres of HIV in genital secretions during HSV2 outbreak
What is the definition of primary genital herpes?
First infection of HSV 1 or 2 in an individual with no pre-existing antibodies to either type
Non primary first episode is forst infection of hsv 1 or 2 but person has antibodies to other type
What may be different about primary HSV in immunocompromised person?
May not resolve spontaneously but persist with development of progressive, eruptive and coalescing mucocutaneous anogenital lesions
Healing may be delayed beyond 2-3 weeks
Systemic symptoms such as fever and myalgia
Rare severe systemic complications - hepatitis, pneumonia, a sceptic meningitis, autonomic neuropathy
What is the typical frequency of genital HSV recurrences in HIV zero negative population?
5 episodes per year for first 2 years and reduce in frequency after
Frequency and severity of outbreaks significantly greater in hiv infected persons with low CD4 counts
How can HSV affect the eye?
Keratoconjunctivitis
Acute retinal necrosis
Possible outcomes of
Pneumonia
Hepatitis
Oesophagitis
CNS disease
What can HSV infection of CNS cause?
Aseptic meningitis (usually a consequence of primary HSV2 infection)
Encephalitis
Myelitis
Radiculopathy
How is HSV diagnosed?
Swabs taken from base of lesion
PCR rapid and sensitive
Culture less sensitive and requires cold chain 4 degrees
How is HSV diagnosed and typed in asymptomatic individuals?
Type specific serology tests detect HSV specific gylcoproteins g1 and g2 which are specific to types 1 and 2 hsv respectively
How is HSV encephalitis or meningitis diagnosed?
CSF - PCR of HSV DNA method of choice. Lymphocytosis and elevated protein, low glucose may occur.
MRI supportive but not diagnostic
Culture not recommended