opportunistic viral infections Flashcards
What’s the definition of opportunities infections and categories
An infection of a niche, not available in healthy people.
Endogenous - latent viruses, acquired prior to immuno-compromised
Exogenous (environment, Iatrogenic,from graft)- increased severity in Immuno-suppressed.
What drugs can induce immunocompromise? (5 types)
Steroids
Calcineurin inhibitors - cyclosporine, tacrolimus
Antiproliferative agents- (DMARDs) Azathioprine, mycophenolate mofetil-organ transplabt, sirolimus
Antibodies - depleting/ non eg anti CD25r ABs,
Co-stimulation blockers
How are viruses detected - investigations
Indirection - immune response (not useful in immunocomp pts) Serology - IgM Active or resolving infection. IgG - past infection >6 weeks
Direct -Viral proteins, genetic material (eg NATs, PCR)
How do you monitor infections in immunocompromised patients
Screen prior to immunosuppression - HIV Ag/Ab, HBV surface ag, core, surface ab, HCV ab, EBV ab, CMV ab, HSVab, VZVab, HTLVab guides prophylaxis
Monitor using PCR - reactivation and new infection.
CMV, EBV, BK, adenovirus (paeds BMT), HSV prophylaxis
What is the order of risk for opportunistic infections (groups of pts)
Worst Allogenic stem cell Advance HIV Solid-organ transplant monoclonal abs cytotoxic chemo DMARDs and steroids
What investigations would you do in a symptomatic immunocompromised patient. Throat swab Bloods CSF Gut biopsy
.
Resp- Flu-A/B, paraflu 1-4, adenovirus, enterovirus, RSV, HMPV, rhinovirus, coronavirus, CMV (on BAL)
Blood- CMV, EBV, Adeno, HHV6, parvo.
CSF- HSV,VZV, enterovirus, EBV, CMV, adenovirus, HHv6, JC virus
Gut biopsy- HSV, CMV, adeno
How does the treatment of viral infections differ in immunocompromised patients
Pre-emptive + prophylaxis ^dosage and duration (increased toxicity) Combination therapy (increased resistance)
How are patients receiving transplants immunosuppressed
Total Body irradiation, cyclophosphamide
Haematological - suppressed for a while after the transplant but will be tapered and return to normal following transplant.
Solid organs - will remain on immunosuppressants forever
What infections are commonly opportunistic viral and fungal
Viral
-CMV, EBV, HSV, VZV, HHV8
-JC and BK
-Influenza A and B, Parainfluenza 1,2,3,4, RSV, Adeno, coronaviruses
Fungi
-Candida, cryptococcal, Aspergillus, dermatophytes, mucormycosi
When does each Flu strain peak
ignore for now
A - H1 - peaks in early January
B H1N1- end of December
B - March
Which infections are most likely following HSCT - <30 days, 30-100 >100
<30
Coagulase negative staph, virdians Step, HSV, Candida, Aspergillus, Gram negatives.
30-100 -
Adeno, CMV, VZV, Aspergillus+ some rarer eg Pneumocystis and toxoplasmagondi
> 100
CMV, VZV, Aspergillus
How do viral infections present differently in immunocompromised patients
May be more severe- disseminated, oncogenic
, may be infections not seen in immuno competent individuals, May be asymptomatic/ non-specific due to a lack of immune response.
How does HSV present differently in immunocompromised patients and how is its management different?
Dissemination - oral, oesophageal, pneumonitis, hepatitis.
Aciclovir resistance
eg HIV maintain CD4<200
Prophylaxisis + regular IgG test if BM or organ transplant
How is VZV different in immunocompromised pts
Dissemination - Varicella - pneumonitis, encephalitis, hepatitis, Purpura fulminans (neonates)
Shingles - multi-dermatomal
VZV management in immunocomp
Prophylaxis (BM), Vaccination
Tx- Chicken pos - antiviral 7-10, IV until no new lesions then PO until crusted
Zoster - IV if disseminated +/- steroids
What is PTLD
Post-transplant lymphoproliferative disease
- Induced by EBV- have suspicion on rising viral load.
Latently infect B cell-> polyclonal activation -> RF for lymphoma.
Confirm with lymph node biopsy
Management of CMV in immunocompromised patients?
Reassurance if immunocompetent
Prophylaxis ( pre transplant- solid organ) /Pre-emptive (check CMV viral load HSCT Ganciclovir - IV 1st line Valganciclovir oral step down Foscarnet- IV Cidofovir IVIg or reduce immunosuppresants
What immunosuppression is JC virus associated with?
HIV, ( antiretrovirals have reduced this)
Monoclonal Abs eg Natalizumab (for MS)
What are the signs and symptoms of progressive mutifocal leukoencephalopathy?
Cognitive disturbance + focal neurology (caused by neuronal demyelination- seen on MRI)
How do you manage viral hepatiis in immunocompromised pts? Each type
A - (more severe) Vaccinate
B- (Re-activation)- Vaccinate/ prophylaxis (lamivudine, tenofovir, entecavir)
C- direct-acting antiviral
E- chronic infection - reduce immunosuppression
Explain the serology of Hepatitis B
surface antigen - cirrculating virus
Core antibody- Current / previous infection - IgG acute, igG/total can show prior, depending on sAg
Surface antibody - from vaccine or virus
