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Human Development 2 > Viral infections in childhood > Flashcards

Viral infections in childhood Flashcards

1
Q

describe the structure of a virion

A
  • nucleic acid
  • protein coat - which is called the capsid
  • might or might not have a envelope
  • nucleocapsid = combination of DNA/RNA with repeating structures of capsomeres
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2
Q

what is a nucelocapsid

A

= combination of DNA/RNA with repeating structures of capsomeres

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3
Q

what are the different types of viruses

A

DNA
RNA

  • Double-stranded DNA
  • (Single-stranded DNA in parvovirus)
  • Single-stranded RNA (+ or – polarity)
  • (Double-stranded RNA in reoviruses)
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4
Q

what virus has single stranded DNA

A
  • single stranded DNA in parvovirus
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5
Q

what virus has double stranded RNA

A

= reovirus

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6
Q

how is most viral diagnosis made

A
  • by PCR
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7
Q

what are viruses

A
  • these are obligate intracellular parasites meaning that they are completely dependent on the cellular machinery
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8
Q

what are the steps in the viral life cycle

A

ATTACHMENT

ENTRY

UNCOATING

SYNTHESIS OF VIRAL COMPONENTS

ASSEMBLY AND RELEASE

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9
Q

describe how viral attachement happens

A

Binding sites on the virus

Receptors (+/- co-receptors) on plasma membrane of cell

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10
Q

what is cell tropism

A

“Cell tropism” – determines what cell the virus can get into

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11
Q

what does it mean if the cell is permissive

A
  • this means it has all the right intracellular components required by the virus to replicate
  • in order for the virus to be able to replicate and survive it has to enter a permissive cell
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12
Q

describe how the virus enters the cell

A
  • Takes from seconds to several minutes
  • Enveloped viruses undergo membrane fusion with the cell membrane
  • May undergo receptor-mediated endocytosis
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13
Q

where does uncoating of the virus take place

A

Endosome (receptor-mediated endocytosis) – due to low pH and lysosomal enzymes

Cytosol

Nuclear membrane

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14
Q

what happens once uncoating of the virus has taken place

A
  • the virus can synthesis more copies of itself
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15
Q

how does synthesis of viral components take place

A

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

All other viruses must synthesize their viral mRNA

May carry their own enzymes (eg RNA polymerase, reverse transcriptase

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16
Q

describe how positive and negative polarity RNA viruses can synthesise there viral components and the difference between them

A

Positive polarity means it already has its RNA to be activated as messenger RNA to be translated and make more virions

Negative polarity – has opposite compoesnation of RNA it needs to make virons, therefore RNA polymerase is needed to mke positive polarity RNA which can be processed by the cell

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17
Q

how does the virus release from the cell

A
  • cell lysis - if this happens this can kill the cell which might not be a good thing for the virus in the long term
  • budding (without cell death)
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18
Q

several thousands of …

A

Several thousand viral particles can be produced per cell

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19
Q

name some DNA enveloped viruses

A

Herpes viruses

  • Herpes simplex
  • Varicella zoster
  • CMV
  • Epstein-Barr
  • HHV 6/7/8

Hepatitis B

Poxviruses

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20
Q

name herpes viruses

A 
Herpes simplex
Varicella zoster
CMV
Epstein-Barr
HHV 6/7/8
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21
Q

name some non-enveloped DNA viruses

A

Papillomavirus

Adenovirus

Parvovirus (ssDNA)

  • spell out PAP, cervical smar for papillomarvirus
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22
Q

what do all enveloped viruses typically cause

A
  • typically cause a rash type illness
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23
Q

How does herpes simplex virus present in the adult

A
  • get herpes labials
  • cold sore
  • herpetic whitlow
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24
Q

how does Herpes simplex virus present in neonates

A

Disseminated HSV

  • Sepsis-like syndrome
  • Hepatitis, coagulopathy

HSV encephalitis

  • Fever, seizures
  • Haemorrhagic infarction of white matter and cortex
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25
Q

How do you treat disseminated HSV

A
  • IV Aciclovir
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26
Q

what are the two HSV presentations in neonates

A

Disseminated HSV

HSV encephalitis

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27
Q

describe what virals are like in early life

A

Often more severe disease – immature antiviral immunity can cause this

More likely to become chronic

Prolonged shedding of the infection - don’t clear the infection as quickly for example CMV can take months or years for the immune system can bring this under control

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28
Q

What is immunity like in early life

A
  • Has evolved to protect babies against extracellular pathogens (bacteria and fungi) which can be rapidly fatal
  • Consequence is that antiviral immunity is less well developed in early life
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29
Q

describe the characteristics of cytomegalovirus

A
  • self-limiting illness
  • sometimes presents like a mononucleosis like illness such as EBV
  • severe disease in immunosuppressed
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30
Q

what is the most comments congenital infection in developed countries

A
  • CMV
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31
Q

what is the main symptoms that CMV can cause

A
  • sensorineural hearing loss
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32
Q

How do you treat CMV

A

For babies with symptomatic disease:

- IV ganciclovir (requires a central line) or oral valganciclovir (pro-drug of ganciclovir) – inhibits DNA synthesis

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33
Q

What can treatment of CMV reduce

A

6 months of treatment reduces hearing loss and improves neurodevelopment

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34
Q

what are the problems with the treatment of CMV

A
  • Neutropenia,
  • thrombocytopenia
  • IV access
  • Long term fertility/malignancy risk
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35
Q

what are the symptoms of CMV

A
  • sensioruneal deafness
  • calcification in the brain
  • hydrocephalus
  • extra medullary haemopoitesis
  • hepatosplenomeagly
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36
Q

what people is varicella zoster virus severe in

A

Severe in immunosuppressed

  • Steroid treatment
  • Chemotherapy
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37
Q

what can varicella zoster virus cause to happen

A
  • can have complications especially in secondary bacterial infection such as staphylcocous and streptococcus that can get in the lesions
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38
Q

what can chicken pox cause to happen in adults

A
  • more server disease - if the host has a robust immune response this can cause pathology this is what happens to adults as they have a more robust immune system than children
  • pneumonitis
  • particular serve in pregnancy women
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39
Q

what are the symptoms of varicella zoster virus

A
  • rash - lasts 4-5 days

- once the lesions have crusted over they are no longer transmittable

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40
Q

what is the goldilocks effect

A

need an immune response that is:

  • not too small - severest disease such as neonatal HSV
  • not too big - immunopathology e.g adult VZV
  • just right
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41
Q

what are the symptoms of EBV in early life versus older children

A 
Usually asymptomatic in early life
Infectious mononucleosis (glandular fever), typically 15-25 yrs old
42
Q

what does EBV stand for

A

Epstein-Barr virus

43
Q

how does EBV spread

A
  • spread by salvia
44
Q

EBV presents differently depending on …

A

geography

45
Q

what does EBV cause in Africa

A
  • Burkitt’s lymphoma
  • EBV infection at early age
  • Plus chronic immunosuppression due to endemic malaria
46
Q

how does EBV effect host immunity

A

Lymphoma in children and adults with advanced HIV disease - people who are immunuosupressed can get an advanced tumour that is driven by EBV

Post-transplant lymphoproliferative disease

47
Q

what is HHV 6 and 7 cause

A

Roseola infantum

48
Q

when do people have roseola infantum

A

Also known as exanthem subitum

Common between 6mo-2yrs of age

49
Q

what are the symptoms of Roseola infantum

A

Sudden onset of high fever, lasts few days then suddenly stops, rash appears

50
Q

Hep B - how does the age of the infection effect how long you have then infection

A
  • if you are born with the infection then you are likely to have chronic infection
  • as you get older there is a lesser chance that you get chronic HepB
51
Q

How does the chances of getting symptoms vary with age in Hep B

A
  • as you get older you are more likely to present with symptoms even though you won’t get chronic HepB whereas if you are younger you might not present with symptoms but you have chronic HepB
52
Q

what are the consequences of chronic Hep B infection

A

Cirrhosis

Hepatocellular carcinoma

53
Q

how is hepatitis B passed from mother to child

A
  • chronic Hep B can be passed down to the baby
  • want to intervene around the time of brith, the E antigen is found in the virus and this tells us about how infectious, if you are E antigen positive then the virus is dividing more rapidly and therefore the risk of transmission is higher
54
Q

How do you reduce the risk of transmission at birth

A
  • give Hep B virus vaccine at birth and then at 1 month of age
  • and HBIG as well (hepatitis B immunoglobulin)
55
Q

what increases your risk of transmission in Hep b

A

eAg-negative 10-20%
eAg-positive 90%

  • being eAg positive - this is because the virus is dividing more rapidly if it has this therefore there is a higher risk of transmission
56
Q

what does poxvirus cause

A

smallpox

molluscum contagiosum

57
Q

how was small pox eradicated

A

Routine vaccination

Isolation of cases lead to outbreak control

58
Q

what are the factors of small pox that aided eradication

A

Severe disease, easy to identify

Slow spread, poor transmissibility

No carrier state, no animal reservoirs

Easy vaccine to produce and distribute

59
Q

What is molluscs contagiosum

A
  • this is often found in most areas such as in the groin and axilla
  • spread by direct contact or fomites
  • mild but can persist fore several years
60
Q

what is a cause of cervcial cancer

A

Papillomavirus

61
Q

what are the serotypes of HPV that can cause cancer

A

HPV 16 and 18

62
Q

what does HPV stand for

A

human Papillomavirus

63
Q

what HPV serotypes lead to genital warts

A

HPV 6 and 11

64
Q

what vaccinations are given for HPV

A

Old:
Cervarix vaccine, bivalent (16, 18)

Current:
Gardasil vaccine, quadrivalent (6, 11, 16, 18)

–given at age 12-13 years

65
Q

what can adenovirus cause

A

URTI / pneumonia

Conjunctivitis

Diarrhoea

Disseminated disease in immunocompromised hosts

66
Q

when is parvovirus not susceptible

A
  • people who do not express the group P antigen are not susceptible as they cannot be infected
67
Q

Who is highly susceptible to parvovirus

A
  • have haematological problems such as sickle cells disease which can lead to an aplastic crisis
  • parvovirus can replicates in rapidly dividing cell which occurs in people who have haematological problems
68
Q

What are the symptoms of parovirus B19

A

Asymptomatic

‘Slapped cheek’ syndrome

Arthropathy (adults) - present with disabling arthritis

Aplastic crisis

Fetal loss in pregnant women

69
Q

What are important RNA enveloped virus

A

Measles, mumps, rubella

RSV, influenza, parainfluenza

Hepatitis C

HIV

  • MMR, RSV, influenza, parainfluenza - respiratory in presentation
  • Hepatisis C, HIV - blood infections
70
Q

What are non enveloped RNA viruses

A

Rotavirus

Enteroviruses (includes polio)

Hepatitis A

  • broadly cause enteric infections and gut infections
71
Q

what is the incubation period for measles

A

7-14 days

72
Q

what are the original symptoms of measles

and then what happens after 2 days and then 2 days after

A

Fever
Cough
Conjunctivitis
Miserable

then after 2 days get kopek spots
then after another 2 days a rash develops - usually starts behind the ear and spread downwards

73
Q

where does the measles rash usually start

A
  • behind the ear and spread downwards
74
Q

what are complications of measles

A

Rare complication

Often in children who were infected at young age (<2 yrs)

Present years later with neurodegenerative disease

and they have developed Subacute sclerosing pan-encephalitis (SSPE)

75
Q

what are the symptoms of rubella

A
  • Fever
  • occipital lymphadenopathy
  • Mild rash
76
Q

what are the symptoms of congenital rubella

A

EYES: cataracts, micro-ophthalmia, glaucoma

EARS: sensorineural deafness

HEART: pulm artery stenosis, VSD

  • Low birth weight, rash, microcephaly
77
Q

what are the three typical congenial infections that we test for

A
  • rubella
  • CMV
  • toxoplasmosis
78
Q

what is bronchiolitis caused by

A

Viral infection of infants (70% RSV)

79
Q

what is bronchitis

A

Inflammation of bronchioles

80
Q

How does bronchiolitis present

A
  • cough
  • respiratory distress
  • wheeze
81
Q

who can bronchiolitis be severe in

A
  • preterm

- congenital heart disease

82
Q

What is the treatment for bronchiolitis

A

Palivizumab (monoclonal Ab) for RSV prophylaxis - given monthly as an injection to high risk babies which prevents them from getting RSV infection

83
Q

How is Hepatitis c treated

A
  • direct antiviral agent’s (DAAs) in past few years
  • 8-12 weeks treatment course with greater than a 95% cure
  • little experience in children yet
84
Q

children below the age of 3 years will….

A

Many children below 3 years of age will spontaneously clear infection and no indication for treatment at young ages

85
Q

why is there little transmission of hepatitis C in children

A
  • lower risk of mother to child transmission, approximately 5%
86
Q

what type of virus is HIV

A

retrovirus

87
Q

how do you prevent mother to child transmission of HIV

A
  • NII
  • AZT
  • Dural ART
  • HAART = 1% transmission rate - can have a normal vaginal delivery
88
Q

HIV infection is more…

A

severe in infants than adults

89
Q

describe HIV in infants

A
  • Higher viral loss
  • rapid progression
  • more likely to develop diarrhoea
  • wasting
90
Q

there are fewer drugs for …

A

HIV in infants

  • toxicity
  • long term costs
91
Q

what are the symptoms of rotavirus

A

Fever
vomiting
watery diarrhoea

92
Q

what vaccines can now be used for rotavirus

A

RotaTeq

RotaRix (included in UK schedule since 2013

93
Q

When was the rotavirus vaccine introduced

A

2013

94
Q

how is the rotavirus vaccine given

A

Oral vaccines are easier to give in mass immunization campaigns

95
Q

what is the rotavirus given

A

2 and 3 months of age

96
Q

why does the oral rotavirus work less well in areas such as Africa and Asia

A
  • due to the gut problems (enteropathy)
97
Q

what viral infections lead to latency

A

CMV, EBV, VZV

98
Q

what viruses can be chronic

A

Hepatitis B

99
Q

what virus is more server and less serve in children

A
  • HSV more severe

- VZV less serve

100
Q

what viruses can be transmitted from mother to child

A

hepatitis B, HIV

101
Q

what viruses can cause cancer

A

papilloma, EBV, hep B

Human Development 2 (34 decks)

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