Viruses Flashcards
Mechanism of action of acyclovir / -ciclorvirs?
Inhibits viral DNA polymerase
Mechanism of action of foscarnet?`
Inhibits viral DNA polymerase and reverse transcriptase and pyrophosphate-binding site
Mechanism of action of Oseltamivir?
Neuraminidase inhibitor - interferes with de-aggregation and release of viral progeny
Mechanism of action of ribavirin?
Interferes with viral messenger RNA
Mechanism of palivizumab?
RSV antibodies
URTI symptoms, flushed cheeks and lacy rash. Arthropathy later. Virus?
Parvo B19
Small DNA virus
Cause of anaemia post Parvo infection?
Transient aplastic crisis - Parvo propagates in erythropoietic cells and myocardial cells.
Increased RBC destruction can cause anaemia if underlying haemolytic disease present
Complications of Parvo infection?
Chronic haemolytic anaemia
Impaired humeral immunity (marrow failure)
Perinatal infection - hydrops fetalis
Management of Parvo?
Supportive. IVIG if aplasia
School exclusion only if RBC aplasia (usually most infectious pre-rash unless viraemic)
High fever & febrile convulsions followed by appearance of mobiliform rash. Leukopenic. Pathogen?
HHV6
Double stranded DNA virus
Complications of HHV6?
Latent in monocytes/macrophages. Reactivation during BMT
Rate of seizures in HHV6?
Most common cause of febrile seizure
1/3 w HHV6 have febrile seizures
Higher rate of complex febrile seizure and post-octal paralysis
Kaposi sarcoma?
HHV8
URTI sx with red eyes, sub occipital/post-auricular/cervical LN and pinpoint petechiae on soft palate. Pathogen?
Rubella
Cause of false positive for rubella IgM?
CMV/EBV
Complications of rubella?
Congenital rubella
Arthritis
Thrombocytopenia/haemolytic anaemia
Myocarditis
Post-exposure prophylaxis for rubella?
MMR vaccine can be given up to 3 days after exposure
School exclusion for rubella?
7 days post rash.
Exclusion up to 1 year old for congenital rubella
Fever, cough, otitis media, white spots in mouth and then rash that started behind ears/on face and spread downwards. Leukopenia and thrombocytopenia. Pathogen?
Measles
Paramyxovirus - single stranded enveloped RNA virus
Virulence factors for measles infection?
Envelope proteins - haemagluttinin and fusion proteins antibodies limit infection
Complications of measles?
Subacute pansclerosing encephalitis - up to 7 years post disease
Encephalitis
Otitis media, pneumonia, myocarditis
Post exposure prophylaxis for measles?
MMR within 72hrs
Immunoglobulin
If declines vaccine then exclude from school for 14 days
URTI sx and parotitis / orchitis. Elevated serum amylase. Leukopenia with lymphocytosis. Pathogen?
Mumps
Single stranded RNA with lipoprotein envelope
Complications of mumps?
Congenital mumps - IUGR, spont abortion in 1st trimester
Orchitis
Pancreatitis
Myocarditis
Low grade fever, malaise, anorexia, 200-500 vesicles. Leukopenia and lymphocytosis. LFT derangement. Pathogen?
Varicella
Neurotropic human herpes virus - enveloped double stranded DNA
Complications of VZV?
Congenital varicella - limb hypoplasia, skin scarring, microcephaly, chorioretinitis, cataracts
Latent infection in dorsal root ganglia - Herpes Zoster
Pneumonitis
Acute cerebellar ataxia
Treatment for VZV?
Aciclovir if immunocompromised, severe eczema, neonatal or severe disease. Needs to be initiated within 24-72hrs of rash onset
Post exposure prophylaxis for VZV?
Vaccine within 72hrs of exposure
VZV IG if vaccine contraindicated (chemo), pregnant, neonate
School exclusion for VZV?
Until all lesions crusted
If contact not consenting to vaccine - isolate for 21 days
Risk factors for CMV in transplant pts?
CMV mismatch (pos donor, neg recipient) Decreased T cell function Transplanting organ with viraemia
Best investigation for CMV?
Urine CMV PCR
IgM not useful - takes weeks/months
Low avidity of IgG for 4-6mths post infection
Treatment of CMV in immunosuppressed pt?
Ganciclovir / foscarnet / cidofivir
Child presents w 2/52 fever, lymphadenopathy, heptosplenomegaly and eyelid edema. Lymphocytosis. Pathogen?
EBV
Complications of EBV?
Splenic rupture
Lymphoproliferative disease - HLH, lymphoid granulomatosis, X-linked lymphoproliferative disease
Hodgkin, Burkitt’s, nasopharyngeal ca
In immunosuppressed pt - oral hairy leukoplakia
Test for EBV?
Monospot - heterophile antibody
Only positive 2-9 weeks post infection
25% false negative in younger children
Bronchiolitis in 6mth old what pathogen?
RSV
RNA virus - enveloped
Does not undergo antigenic shift
RFs for RSV / indications for palivizumab?
CLD
Congenital heart disease and <2yrs old
Prem <28 weeks
LRTI and hemorrhagic cystitis. Pathogen?
Human metapneumovirus
2nd most common URTI cause after RSV
Double stranded DNA virus
Hand, foot, mouth blisters with fever. Outbreak in summer/autumn at daycare. Pathogen?
Coxsackie A
Acute hemorrhagic conjunctivitis. Well systemically. Pathogen?
Enterovirus / coxsackie A24
Most common cause of viral myocarditis/pericarditis?
Coxsackie B
Antigenic shift?
Point mutation in respective gene, causes variant to be predominant virus
Antigenic drift?
Sudden appearance of new HA subgroup - new surface antigens now means no prev immunity conferred
Only occurs with influenza A virus
Oseltamivir mechanism of action?
Neuraminidase inhibitor
Contraindications to rotavirus vaccine?`
Anaphylaxis
Prev intussusception or anatomical variant pre-disposing to intussusception
SCID
HPV assoc w genital warts?
6, 11
HPV assoc w cervical ca?
16, 18
Primary route of HIV transmission in kids?
Vertical
30-40% intra-uterine
60-70% intra-partum
elLUSCS reduces risk by 87%
Zidovudine mechanism of action?
Reverse transcriptase inhibitor
SEs - lactic acidosis, hepatic steatosis
Traveller returned from Cambodia/Thailand - fever and myalgia ++, retro-orbital pain and when tourniquet applied for venepuncture petichiae are noted. Pathogen?
Dengue
Negri body. Pathogen?
Rabies
Transplant nephropathy. Pathogen?
BK virus
