4. Viral Infections in Childhood Flashcards
What viruses have ssDNA or dsRNA?
Describe the 5 steps in the viral life cycle.
Parvovirus (ssDNA), reoviruses (dsRNA)
1) Attachment: binding sites on virus and receptors on cell plasma membrane, cell must be permissive
2) Entry: s/min, enveloped viruses undergo membrane fusion. May be receptor mediated endocytosis.
3) Uncoating: takes place in endosome/cytosol/nuclear membrane, transport to right part of cell for step 4
4) Synthesis of viral components: need viral mRNA to enable peptide and nucleic acid syntheisis. DNA viruses use cell enzymes. Many carry own enzymes e.g. RNA pol
5) Assembly and release: via cell lysis/budding
What are some important enveloped and non-enveloped DNA viruses?
What might you observe if an older child or adult had herpes simplex?
What might you observe if a neonate had herpes simplex?
Enveloped: herpes viruses (herpes simplex, herpes zoster, CMV, Epstein-Barr, HHV 6/7/8), Hep B, Poxviruses. Non-enveloped: papillomavirus, adenovirus, parvovirus (ssDNA). Enveloped tend to cause infections characterised by rash. Non spell out PAP
Cold sore, herpetic whitlow
Disseminated HSV (sepsis-like syndrome, hepatitis, coagulopathy, high mortality, treat with IV acyclovir), HSV encephalitis (fever, seizures, haemorrhagic infarction of white matter and cortex)
What are childhood viral infections in early life like compared to adult infections?
Why is this?
Describe CMV.
What can congenital CMV cause in the longterm?
How is congenital CMV treated?
More severe, more likely to become chronic, prolonged shedding.
Immunity evolved to protect babies against extracellular pathogens (bacteria and fungi) which can be rapidly fatal. Antiviral immunity not well developed in early life. Timing of infection has major impact on outcome.
Cytomegalovirus. Self-limiting illness. Rash, big glands, fever. Severe in immunosupressed.
Hearing deficit, neuro-developmental delay
If symptomatic: oral valganciclovir (inhibits DNA synthesis)
Describe varicella zoster virus.
What is the ‘Goldilocks’ effect?
Common in childhood, usually uncomplicated, severe in immunosupressed (steroid treatment, chemo), can have complications esp in 20 bacterial infection. Chicken pox rash. More severe in adults due to bigger T cell response, can cause pneumonia.
Need immune response that is not too small (severe disease e.g. neonatal HSV) and not too big (immunopathology e.g. adult VZV) - need one just right.
What are the impacts of age, geography and host immunity of EBV?
What is roseola infantum?
Age: usually asymptomatic early in life, spread by saliva, infectious mononucleosis (glandular fever). Geography: Burkitt’s lymphoma in Africa: EBV at early age + chronic immunosupression due to endemic malaria, affects mandible. Host immunity: lymphoma in children and adults with advanced HIV. Post-transplant lymphoproliferative disease.
Caused by HHV 6 and 7, “exanthum subitum”, 6m-2y, sudden onset of fever, lasts a few days then suddenly stops, rash appears as kid gets better. [pic]
What are the trends of chronic infection and symptomatic infection of hepatitis B with age?
What are 2 consequences of chronic hepatitis B infection?
Hepatitis B can be passed from mother to child. What marker is used to see how infectious the virus is, and what interventions are given?
More likely to become chronic the younger you are when you acquire it. Symptomatic infection increases with age as immune response kicks in (kids tend to be asymptomatic)
Cirrhosis, hepatocellular carcinoma
eAg: E antigen found in middle of DNA virus, amount = marker of how infectious it is. Screening during pregnancy. Vaccine +/- HBIG.
How was smallpox eradicated?
What does papillomavirus cause?
What are some symptoms of adenovirus?
Routine vaccination, isolation of cases. Aided by: easy to identify, slow to spread and transmission poor, no animal reservoirs or carrier state, easy vaccine to produce and distribute
Cervical cancer (serotypes 16, 18). Genital warts (serotypes 6, 11). Vaccine given to adolescent girls.
URTI/pneumonia, conjunctivitis, diarrhoea, disseminated disease in immunocompromised hosts
What condition is this?
Molluscum contagiosum in normal host (top 2) and immunocompromised host (bottom 2). In pox virus family. Umbilicated lesions (dome shaped), in moist areas.
Differentiate between the effect of parvovirus B19 on unsusceptible and highly susceptible hosts.
What can parvovirus B19 cause?
Unsusceptible: attaches to blood group P antigen, so if lacking it, not susceptible. Highly susceptible: replicates in reticulocytes, so in people with haematological problems e.g. sickle cell = aplastic crisis (palor, breathlessness, low Hb)
Asymptomatic, slapped cheek syndrome, arthropathy, aplastic crisis, fetal loss
List some important enveloped and non-enveloped RNA viruses.
What are the symptoms of measles?
What is a rare long term consequence of acute viral infection of measles?
Enveloped: MMR, RSV, influenza, parainfluenza, Hep C, HIV. Non-enveloped: rotavirus, enteroviruses (inc. polio), Hep A. Enveloped tend to be respiratory or tropical (ebola etc.) + HIV and Hep C. Non-enveloped mostly enteric + hep A = diarrhoea and vomiting
Fever, cough, conjunctivitis, miserable. Macular rash starts behind ears and spreads downwards. 2 weeks incubation after exposure.
Subacute sclerosing pan-encephalitis (SSPE), often infected <2yrs and present years later with neurodegenerative disease
What is rubella? What are some signs/symptoms?
What is the classic triad of congenital rubella? What are some other symptoms/signs?
What viral infection of infants does RSV, influenza and parainfluenza cause? What are the signs/symptoms?
What is given to prevent this viral infection?
Mild, german measles, fever, occipital lymphadenopathy, mild rash.
Eyes (cataracts (so shine light into newborn’s eyes to see red retinal reflex = OK), micro-ophthalmia, glaucoma), Ears (sensorineural deafness), Heart (pulmonary artery stenosis, VSD). Low birth weight, rash, microencephaly.
Bronchiolitis: inflammation of bronchioles. Cough, respiratory distress, wheeze. Can be severe in preterm, congenital heart disease.
Palivizumab (monoconal Ab)
What is used to prevent mother to child transmission of HIV?
Why is HIV infection more severe in infants than adults?
What are some signs/symptoms of rotavirus?
HAART: control viral loads to undetectable levels.
High viral loads, rapid progression, no reliable markers, fewer drug options, challenging adherence, long-term costs, toxicity of antiretrovirals
Fever, vomiting, watery diarrhoea. Oral rotavirus vaccines now being given, but less immunogenic in Asia/Africa b/c gut prob chronically inflamed
List some viruses that can:
a) become latent
b) be more severe or less severe than adults
c) lead to chronicity
d) be transmitted from mum -> child
e) cause congenital infection
f) cause cancer
g) be eradicated
a) CMV, EBV, VZV (all herpes viruses)
b) more severe = HSV, less severe = VZV
c) Hep B
d) Hep B, HIV
e) CMV, rubella, herpes, VZV
f) papilloma, EBV, Hep B
g) smallpox, polio (soon)
