Opportunistic Viral Infections Flashcards
What are opportunistic viral infections?
Those occurring in immunocompromised individuals with more severe presentations.
- Viral infection of a niche not available in the healthy
- ‘Endogenous’
- Latent viruses that reactivate in absence of immune system
- Acquired in past prior to immune suppression e.g. Varicella Zoster
- ‘Exogenous’
- Viruses acquired from environment
- increased severity in immunosuppressed e.g. Influenza, SARS-CoV-2
Which infections may occur more frequently or more severely in immunocompromised individuals?
Occur more frequently in immunocompromised
CMV, EBV, HSV
More severe presentation
VZV, Measles.
How may infection exist in immunocompromised individuals?
Absence or diminution in signs of infection
40% of infections post solid organ transplant were afebrile
Loss of localizing signs (peritonism and steroids)
Fever could be due to non-infectious causes
22% of fevers in solid organ transplant recipients
What problems does impaired ability to respond normally?
Metabolic/ Endocrine:
Alcohol Abuse
Diabetes Mellitus
Uraemia
Malnutrition
Impaired Barriers to Infection:
Burns
Haemodialysis
IVDU
Pregnancy, Extremes of Age
What are the types of immunodeficiency?
Primary immunodeficiency
UNC93B deficiency and TLR3 deficiency leading to predisposition to herpes simplex encephalitis, Epidermodysplasia verruciformis, SCID, haemophagoytic lymphohistiocytosis in perforin deficiency.
Acquired immunodeficiency
Solid organ transplantation
Bone marrow transplantation
Immunosuppressive drugs
Advanced HIV infection
Which virus and which genetic lesion?
EBV/perforin
HSV/UNC93B
HPV/EVER1 or EVER2
HHV8/STIM1
None of the above
HSV/UNC93B
How do we predict risk of opportunistic infections in HIV?
Risk of developing specific opportunistic infections can be predicted from CD4 count
AIDS defining illnesses (reference only)
Candidiasis of the esophagus, bronchi, trachea, or lungs
Cervical cancer, invasive
Coccidioidomycosis, disseminated or extrapulmonary
Cryptococcosis, extrapulmonary
Cryptosporidiosis, chronic intestinal (greater than one month’s duration)
Cytomegalovirus disease (other than liver, spleen, or nodes)
Cytomegalovirus retinitis (with loss of vision)
Encephalopathy, HIV related
Herpes simplex: chronic ulcer(s) (more than 1 month in duration); or bronchitis, pneumonitis, or esophagitis
Histoplasmosis, disseminated or extrapulmonary
Isosporiasis, chronic intestinal (more than 1 month in duration)
Kaposi sarcoma
Lymphoma, Burkitt’s (or equivalent term)
Lymphoma, immunoblastic (or equivalent term)
Lymphoma, primary, of brain
Mycobacterium avium complex or M kansasii, disseminated or extrapulmonary
Mycobacterium tuberculosis, any site (pulmonary or extrapulmonary)
Mycobacterium, other species or unidentified species, disseminated or extrapulmonary
Pneumocystis jiroveci pneumonia
Pneumonia, recurrent
Progressive multifocal leukoencephalopathy
Salmonella septicemia, recurrent
Toxoplasmosis of brain
Wasting syndrome due to HIV
How does transplant affect immunocompromise?
Ongoing immunosuppression
What are major immunosuppressants?
From highest to lowest risk, what causes most risk of viral infection?
Allogeneic stem cell transplant
Advanced HIV infection (CD4 dep)
Solid organ transplant
Various monoclonal antibody therapies
Cytotoxic chemotherapy
DMARDs and steroids
What changes state of immunosuppression?
}Immunosuppressive Treatment
◦Type, Timing, Intensity
}Prior Treatment
◦Antimicrobial use, Chemotherapy
}Muco-cutaneous Integrity
◦Catheters, lines, drains
}Surgical Complications
◦collections
}Metabolic Conditions
◦Uraemia, alcoholism, DM, age
}Viral Infection
◦Herpesviruses, HBV, HCV, HIV, RSV,respiratory virus
What is the timeline of infection from a solid organ transplant?
How do post transplant infections happen?
What pre transplant serology is needed?
Pre-transplant serology
}HIV Ag/Ab
}HBV sAg
}HBV cTAb
}HBV sAb
}HVC Ab
}EBV IgG
}CMV IgG
}HSV IgG
}VZV IgG
}HTLV Ab
CMV monitoring or prophylaxis
EBV monitoring
Adeno monitoring (paeds BMT)
HSV prophylaxis if indicated
Which bugs can you test for in the CSF?
HSV
VZV
Enterovirus
EBV
CMV
Adenovirus
HHV6
JC virus
Which bugs can you test for in the blood?
CMV
EBV
Adeno
HHV6
Parvo
What bugs can you find in respiratory secretions?
Flu A/B (Oseltamivir (oral drug) for 5 days, If resistance/severe/immunosuppressed → zanamivir (inhalation or IV))
Paraflu 1-4
Adenovirus
Enterovirus
RSV
HMPV
Rhinovirus
Coronaviruses
CMV in BAL
SARS CoV-2 (Tx with Sotrovimab or Casirivimab/imdevimab)
What bugs can you find on gut biopsy?
HSV
CMV
Adeno
What is the treatment?
}Opportunistic viral infections are often more difficult to treat
}Often requires
◦Early treatment
◦higher dose
◦longer course
◦sometimes drug combinations
}Increased risk of antiviral drug resistance
What are HHVs?
◦Herpes simplex virus (HSV) 1 & 2
◦Varicella zoster virus (VZV)
◦Cytomegalovirus (CMV)
◦HHV6 : Human herpes virus 6
◦Epstein Barr Virus (EBV)
◦HHV-8
What kind of viruses are the herpesviruses?
}DNA viruses
}Latent infection
◦Only a small subset of genes are expressed
◦Reactivation can occur leading to the expression of viral genes and production of progeny virus
Leads to destruction of the host cells
What do herpes viruses cause?
Most commonly
Cold sores, stomatitis, mouth ulcers
Recurrent genital disease (HIV and adult transplant
Serious complications
Cutaneous dissemination
Oesophagitis
Hepatitis
Viraemia
Treatment
Aciclovir or valaciclovir
Foscarnet
(Ganciclovir sensitive also)
When does HSV show up after transplant?
HSV reactivation in the pre-engraftment period
Aciclovir prophylaxis until CD4 count increases above a certain threshold or for specific time period
What is VZV?
}Varicella (primary infection)
Carries an Increased risk of complications:
◦Pneumonitis
◦Encephalitis
◦Hepatitis
◦Purpura fulminans in neonate
How does shingles reactivate post transplant?
- Shingles-often late complication post-transplant
- Shingles can be early sign of HIV infection-indication for HIV testing particularly in young person
- Multidermatomal or disseminated zoster is associated with high mortality
How may VZV in immunocomprised present?
Acute retinal necrosis (ARN)
Progressive outer retinal necrosis (PORN)
VZV-associated vasculopathy
What is VZV prevention?
Aciclovir prophylaxis provides some protection
Post-exposure prophylaxis of varicella with VZIg
What is VZV treatment?
}Aciclovir (first line)
}Valaciclovir
}Foscarnet sensitive
}Ganciclovir sensitive
What is the presentation of CMV?
When does CMV present post transplant?
In transplant the risk of CMV disease relates to pre-tx serostatus
solid organ transplant
D+/R- : carries the greatest risk of reactivation
bone marrow transplant: adoptive immunity
D-/R+ : carries the greatest risk of reactivation
What is CMV prevention strategies post-transplant?
CMV viral load twice weekly, treat if virus reactivates until suppressed (pre-emptive therapy)
Valganciclovir prophylaxis for 100 days
What is CMV treatment?
Prophylaxis (i.e. lung transplant)
Pre-emptive treatment (i.e. renal transplant / HSCT)
Treat if disease (HIV/AIDS)
Rx: Ganciclovir / Valganciclovir
Rx: Reduce immunosuppression
- Ganciclovir (IV): bone marrow suppression
- Valganciclovir: oral
- Foscarnet (IV) (nephrotoxicity)
- Cidofovir (nephrotoxicity)
- IVIg (with another drug for pneumonitis)
What are the phases of EBV?
Acute phase: febrile illness with lymphadenopathy & moderate hepatitis
After the acute phase: lifelong, latent, subclinical infection of B cells.
Intermittent attempts at viral replication kept in check by immunosurveillance
EBV stimulates host cells to divide – also kept in check.
In EBV/PTLD, illustrate immunosurveillance breakdown
Post-transplant lymphoproliferative disease (PTLD)
◦Latently infected B cells – polyclonal activation
◦Predisposes to lymphoma
◦suspicion on rising EBV viral load (> 105 c/ml) and CT scan
◦Confirmation with biopsy of lymph nodes
◦Management:
Reduce immunosuppression (regression in < 50%)
Anti-CD20 monoclonal Ab therapy (B cell marker) (“rituximab”)