Viral Flashcards
Mechanism of acyclovir?
nucleoside analogue which inhibits viral DNA polymerase
Indications for acyclovir?
HSV type 1 and type 2
VSV
occasional EBV
Precautions in prescribing acyclovir?
Reduce dose in renal impariment as crystalises in the tubules
Rare - neurologic toxicity
Mechanism of gancylcovir?
nucleoside analogue which inhibits viral DNA polymerase
Indications for Gancyclovir?
CMV
Side effects of gancyclovir?
Resistance can develop through target site mutations (ie. DNA polymerase)
Myelosuppression
Renal impairment
Mechanism of action of Ostelmavir?
Neramindase inhibitor
- prevents budding of virus from host cell
Indications for Ostelmavir?
Influenza A and B
Side effects of Foscarnet?
Renal insufficiency
Electrolyte wasting - low K, MG, phos, Ca
Clinical features of CMV infection?
Prolonged fever, night sweats, malaise, anorexia, fatigue, arthralgias
Deranged LFTs, leucopenia, thrombocytopenia, and atypical lymphocytes
Lung involvement: SOB, hypoxia, non productive cough with bilateral interstitial infiltrates that begin in the periphery of lower lobes and spread upwards
GI involvement: oesophageal ulcers, stomach, small intestine or colon, hepatitis (particularly after liver transplant)
What complications of CMV occur more frequently in HIV patients?
Meningioencephalitis and retinitis particularly in HIV patients
Highest risk time period for CMV after transplant??
1-4 months following transplant
Possible treatment options for CMV?
Valgancyclovir
Gancyclovir
Foscarnet
Cidofovir
Complications of EBV in the immunocompromised?
EBV lymphoproliferative disorder
Oral hairy leukoplakia in HIV patients
Manifestations of HHV-6 in immunocompromised?
Cytopenias
Limbic encephalitis
Hepatitis
Pneumonitis
Manifestations of HHV-8 in immunocompromised?
Kaposis sarcoma
Castlemans disease
Primary effusion lymphoma
How does ebola virus enter the cell?
glycoprotein 1 and 2 on the surface of virus bind to cell surface markers
How does MERs-Cov enter the cell?
Enters via DPP-4 on non ciliated bronchial cells
What type of virus is the ebola virus?
Filovirus
What type of virus is dengue?
Flavivirus
What are the phases of infection with dengue?
inital: fever, retroorbital pain, rash, arthralgia, headache, back pain
defeverescence: occurs around 3-7 days (at risk for getting critical disease - haemorrhagic fever/shock syndrome)
recrudescence: rash, skin desquamation and fever
recovery
Complications of Dengue?
Dengue shock syndrome = haemorrhagic dengue + shock
Increased vascular permeability
Marked thrombocytopenia
Torniquet test - petichiae
Diagnosis of dengue?
serology - arbovirus Igm/IgG
NS1 antigen can be tested early and is specific
Bloods - plts less than 100 and raised LFts = severe disease
Vector of dengue?
Aedes aegyptii
Countries that have dengue?
Across equatorial band
- occurs in northern queensland
What is the incubation period?
3-10 days
Greater then 14 days - excludes diagnosis
Tests for EBV?
Blood film - atypical lymphocytes Heterophile antibodies (aka Paul Bunnell/Monospot - not sensitive or specific EBV serology more specific - VCA IgM/IgG and EBNA - last for life
Causes of infectious mono
EBV most common - 90%
CMV
Toxoplasmosis
HIV
What infections do you get with HSV-1?
Oral ulcers
Meningoencephalitis
What infections do you get with HSV-2?
Genital ulcers - painful lesions
Meningitis
What does antigen shift mean (in context of influenza)
Major genetic reassortment of surface proteins (Haemagglutinin & Neuraminidase)
Cause pandemics as population has not previously been exposed
What does antigenic drift mean (in context of influenza)
Point mutations in surface proteins resulting in small change
Cause epidemics/local outbreak as population has seen part of virus before
Complications of influenza
Pneumonia - viral and secondary bacterial
Myositis
Rhabdomyelitis
CNS involvement - transverse myelitis, GBS, aseptic meningitis
Myocarditis/pericarditis
Groups at high risk for severe influenza
Children 65 Chronic illness Pregnant Obesity Immunocompromised - particularly IgG2 Asthma
5 types of illness from Parvovirus B19
Slapped cheek - erythema infectiosum Polyarthropathy syndrome Transient aplastic crisis Fetal infection Chronic infection in immunosuppressed host
