Viral Infections in Childhood Flashcards
What forms the nucleocapsid?
Nucleic acid and protein coat (capsid)
DNA viruses are usually ____-stranded and RNA ____-stranded.
Double
Single
What is the exception to the rule that DNA viruses are usually double stranded?
Parvovirus (single stranded)
What is the exception to the rule that RNA viruses are usually single stranded?
Reoviruses (double stranded)
What are the five steps in the viral life cycle?
- ATTACHMENT
- ENTRY
- UNCOATING
- SYNTHESIS OF VIRAL COMPONENTS
- ASSEMBLY AND RELEASE
What is required for step 1 of the viral life cycle (attachment)?
Cell must be permissive (ie have all the right intracellular components required by the virus to replicate) and have receptors (and co-receptors) on the plasma membrane of the cell. There must also be binding sites on the virus.
What happens in step 2 of the cycle (entry)?
How long does it take?
Enveloped viruses undergo membrane fusion and may undergo receptor-mediated endocytosis.
Seconds to minutes
Where can step 3 take place (uncoating)?
What does it result in?
Endosome, cytosol, nuclear membrane
Results in transport to the right part of the cell to begin new virion production
What does step 4 involve/require?
Requires viral mRNA to enable viral polypeptides and nucleic acid to be synthesized by cell machinery. DNA viruses that enter the nucleus can use only cellular enzymes, but all other viruses must synthesize their viral mRNA (may carry their own enzymes).
What does step 5 involve/require?
New virions assembled and are released by cell lysis.
What are the important enveloped DNA viruses in this lecture?
Herpes viruses (herpes simplex, varicella zoster, CMV, Epstein-Barr, HHV 6/7/8)
Hepatitis B
Poxviruses
What are the important non-enveloped DNA viruses in this lecture?
Papillomavirus
Adenovirus
Parvovirus (single stranded DNA)
What does herpes simplex cause in neonates? (2)
Disseminated HSV - a sepsis-like syndrome with high mortality. It causes hepatitis and coagulopathy.
HSV encephalitis - this presents with fever and seizures. There is haemorrhagic infarction of white matter and cortex.
How is disseminated HSV treated?
IV aciclovir
What can be said about viral infections in early life? (3)
Often more severe
More likely to become chronic
Prolonged shedding
Why are viral infections more severe in early life?
Antiviral immunity is not well developed
Cytomegalovirus - for which population of patients is this NOT subclinical/self-limited?
What types of symptoms does it cause?
Immunosuppressed
Mononucleosis-type illness
What is the most common congenital infection in developed countries?
Congenital CMV
How many % of babies with congenital CMV are symptomatic at birth?
10%
What are the long-term complications of congenital CMV?
Long term hearing deficit
Neuro-developmental delay
How is congenital CMV treated?
IV ganciclovir or oral valganciclovir (pro-drug) – this inhibits DNA synthesis
6 months of treatment
What are the problems associated with long-term treatment for congenital CMV?
Neutropenia
Thrombocytopenia
IV access
What treatments might cause varicella zoster to be severe? (2)
Steroid treatment
Chemotherapy
What are the complications of varicella zoster?
Secondary bacterial infection
Is chickenpox more severe in children or adults?
What can it cause?
Adults (particularly pregnant women)
Pneumonitis
Epstein Barr Virus - how does it present in early life vs when 15-25 years old?
Usually asymptomatic vs infectious mononucleosis (glandular fever)
What is Burkitt’s lymphoma caused by?
EBV infection at early age plus chronic immunosuppression (e.g. due to endemic malaria in Africa).
What is caused by HHV 6 and 7?
When is it common?
Roseola infantum (also known as exanthem subitum) 6 months to 2 years
How does roseola infantum present?
Sudden onset of high fever, lasts few days then suddenly stops and a rash appears.
What are the four stages of Hep B?
Tolerance
Clearance
Latency
Reactivation
What are the consequences of a chronic hep B infection? (2)
Cirrhosis
Hepatocellular carcinoma
When was smallpox eradicated and how?
1977
Combination of routine vaccination and isolation of cases (outbreak control). It is a severe disease that is easy to identify and has poor transmissibility due to slow spread. There are no animal reservoirs or carrier state. The vaccine was easy to produce and distribute.
Where is Molluscum contagiosum often found? How is it spread?
Moist areas e.g. groin, axilla
Spread by direct contact or fomites
What is papillomavirus a cause of?
Cervical cancer
Which papillomavirus serotypes are carcinogenic? Which vaccine protects against these?
Serotypes 16, 18 - Cervarix
Which papillomavirus serotypes cause genital warts?
Serotypes 6, 11
Which vaccine protects against HPV serotypes 6, 11, 16 and 18?
Gardasil
What does adenovirus cause?
Upper resp tract infection/pneumonia
Conjunctivitis
Diarrhoea
Disseminated disease in immunocompromised hosts
Where does parvovirus B19 attach to?
Blood group P antigen
In people with haematological problems, parvovirus replicates in _____ ____ cells (____ ____ precursors). What does this lead to?
Rapidly dividing cells (red cell precursors)
Aplastic crisis
What is another name for parvovirus?
‘Slapped cheek’ syndrome
What are the important enveloped RNA viruses in this lecture?
Measles, mumps, rubella
RSV, influenza, parainfluenza
Hepatitis C
HIV
What are the important non-enveloped RNA viruses in this lecture?
Rotavirus
Enteroviruses (includes polio)
Hepatitis A
Which viruses lead to latency? (3)
CMV, EBV, VZV
How long is the incubation period for measles?
7-14 days
What are the symptoms of measles?
Fever, cough, conjunctivitis, miserable
What sign is pathognomonic of measles?
Koplik spots
What long term neurological consequence can measles have?
Subacute sclerosing pan-encephalitis (SSPE) - these children are often infected at a young age and present years later with neurodegenerative disease.
What is another name for rubella?
German measles
What are the signs/symptoms of rubella?
Fever
Occipital lymphadenopathy
Mild rash
What are the signs/symptoms of congenital rubella?
EYES: cataracts, micro-ophthalmia, glaucoma
EARS: sensorineural deafness
HEART: pulmonary artery stenosis, VSD
Low birth weight, rash, microcephaly
What is bronchiolitis?
Viral infection of infants, causing inflammation of bronchioles.
What causes 70% of bronchiolitis?
RSV
What are the signs/symptoms of bronchiolitis?
Cough, respiratory distress, wheeze
How is bronchiolitis prevented?
Palivizumab (monoclonal antibody)
Is HIV more severe in infants or adults? Why?
Infants
High viral load, rapid progression, no reliable markers, fewer drug options, challenging adherence, long-term costs, toxicity of antiretroviral drugs…
What is the most common cause of hospital admission in Europe/USA?
Rotavirus diarrhoea
What are the symptoms of rotavirus infection?
Fever, vomiting, watery diarrhoea
What two oral vaccines are now being rolled out for rotavirus?
RotaTeq
RotaRix
