Virology Flashcards
Intrauterine vs perinatal infection
before birth vs in 1w after birth
5 significant intrauterine infections
Rubella
CMV
VZV
Parvovirus B19
Zika
3 important perinatal infections
HSV1/2
Enterovirus
HPV
How many adults are immune to rubella?
90%
Transmission of rubella
Aerosol
Presentations of rubella (3)
morbilliform rash (face to trunk to limbs)
fever, malaise
small joint pain
Congenital infection of rubella and sequels on the foetus
<12w: congenital rubella syndrome (90%)
cataract, glaucoma, deafness, retardation, PDA, DM
12~16w: deafness (20%)
Diagnosis of rubella
- Serology (IgM, serum acute + convalescent)
- PCR on urine / NPA / amniotic fluid
Management for congenital rubella syndrome
<16w: counselling for termination of pregnancy
isolation
Vertical transmission rate of CMV
40% for primary infection
1-3% for activation / reinfection
Congenital infection of CMV (2)
Congenital cytomegalic disease (10-15%)
deafness (10%)
Diagnosis of CMV congenital infection
[before birth] amniotic fluid PCR
[after birth] urine / saliva PCR
Why CMV serology is not applicable in screening and diagnosis of congenital infection? (3)
- CMV IgG +ve in most adults –> screening not effective
- immaturity of baby to produce IgM
- could be FP by passively acquiring IgG from mother
What’s the difference between congenital and post-natal infection of CMV? How to determine which is which?
- post-natal infection will not cause cytomegalic disease
- if sample +ve within 3 weeks, it must be congenital. Otherwise it is hard to determine
% of adults with VZV IgG +ve
90%
Congenital infection of VZV: timeframe
<20w: congenital varicella syndrome (1~2%)
>20w: zoster
perinatal (5d pre and 2d post): severe congenital varicella syndrome (fatal)
Diagnosis of VZV congenital infection
clinical (seldom do vesicular swab)
Management for risk of VZV congenital infection
Post-exposure prophylaxis by VZIG if the mother is susceptible
% of adults having Parvovirus B19 IgG
30%
Transmission of parvovirus B19
aerosol, blood products
Presentations of parvovirus B19 infection
- 50% asymptomatic
- 5th disease / erythema infectiosum (“slapped face” rash)
- arthritis
Congenital infection of parvovirus B19
all or none
anaemia, hydrops fetalis (25~33%)
Transmission of Zika
vector borne, sexual, blood transfusion
intra-uterine, breast milk
Diagnosis of Zika congenital infection
[Before birth]
1. Serology: IgM (acute + convalescent)
2. PCR on urine & blood
(timing: within 14 days from onset / back from endemic areas)
3. PCR on aminotic fluid / cord blood
[After birth]
- <7d: PCR on CSF
- >7d: IgM
Antenatal screening in HK (3)
Rubella IgG
HBsAg
HIV antibodies
What if antenatal screening reveals HBsAg positive on a pregnant lady?
- give antiviral (tenofovir) for mother at ~32w
- give hyperimmune globulin + vaccine for newborn
Which congenital infection can result in microcephaly? (2)
VZV, Zika
Vector for Zika virus
Aedes mosquitoes
Respiratory viruses that are more common in children (2)
RSV, Parainfluenza
Respiratory viruses (7)
Influenza, Adenovirus, RSV, Parainfluenza
Rhinovirus, Enterovirus, Coronavirus
Basic virology for influenza virus (family, genome, replication, envelop?)
Family: Orthomyxoviridae
Genome: (-) ssRNA, 8 segments
Replication: in nucleus
Enveloped with antigens
Types of antigens of Influenza virus (number of subtypes)
Haemaglutinin (18), Neuraminidase (11)
Groups of influenza virus
A~D (MC is A, only A, B, C infect human)
Diagnosis for influenza virus (2)
NPA for RT-PCR
Rapid antigen test by direct IF assay
3 classes of antivirals against influenza virus, examples of drugs (2+2+1), actions
M2 ion channel blocker:
- Amantadine, Rimantadine
- inhibit viral uncoating
Neuraminidase inhibitor:
- Zanamivir, Oseltamivir
- inhibit release
Cap depenpent endonuclease inhibitor:
- Baloxavir
- inhibit RNA transcription
Which class of antiviral against influenza is for group A only
M2 ion channel blocker
Vaccine types for influenza (2)
- Inactivated vaccine (injected)
- Live attenuated vaccine (intranasal)
Which pathogen causes formation of multinulceated giant cells?
RSV
Family and groups of RSV
Pneumoviridae
A, B
MC pneumonia in children
RSV
Treatment / Prophylaxis for RSV
Palivizumab 帕利非
Serotypes of parainfluenza virus
1,2,3,4a,4b
Subgenera of adenovirus
A~G
Family, genome, and groups of Rotavirus
Reoviridae, dsRNA, A~E
MC viral GE inchildren
Rotavirus
Diagnosis of rotavirus
Stool or rectal swab
antigen detection by enzyme immunoassay or latex agglutination
(microscopy)
Vaccines for rotavirus (2) (nature) (time) (complication)
RotaRix, RotaTeq
[oral] live attenuated vaccine
1st dose 6-15w, 2nd dose before 32w
intussuception
Which 2 serotypes of adenovirus can cause enteric infection?
40, 41