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YEAR 5: Microbiology and Infection > MI: Viral Infections in Pregnancy > Flashcards

MI: Viral Infections in Pregnancy Flashcards

1
Q

What are the three times at which viral infections can be transmitted from the mother to the baby?

A
  • In utero
  • Perinatally (from vaginal secretions and blood)
  • Postnatally (from breast milk and other sources)
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2
Q

What type of virus is rubella?

A
  • RNA virus
  • Togaviridae family
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3
Q

Describe the mechanisms of teratogenicity of rubella.

A
  • Decrease in rate of cell division (leading to structural malformation)
  • Decrease in overall number of cells (small babies)
  • Interference with the development of key organs
  • Tissue necrosis due to viral replication
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4
Q

What is the classic triad of congenital rubella syndrome?

A
  • Sensorineural hearing loss
  • Congenital cardiac defects (mainly PDA)
  • Eyes - cataracts, retinopathy, microphthalmia
  • Other: mental retardation, meningoencephalitis, microcephaly, hepatosplenomegaly, thrombocytopaenic purpura
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5
Q

Describe the relationship between gestation at which rubella infection occurs and the risk of congenital abnormalities.

A
  • Highest risk from 0-12 weeks
  • Low risk from 13-20 weeks
  • Very low risk >20 weeks
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6
Q

Describe some tests that are used in the diagnosis of rubella.

A

Rubella IgG

  • Seroconversion - if woman initially has negative IgG but then has a positive IgG result after possible exposure, it suggests that they have been exposed to rubella
  • Avidity - high avidity means that exposure occured > 3 months ago
  • This is part of routine antenatal screening

Rubella IgM

Detection of virus (PCR) - blood, urine, tissues

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7
Q

What is the role of pre-natal diagnosis of rubella?

A

All cases of symptomatic rubella infection in the 1st trimester should be considered for termination of pregnancy without prenatal diagnosis

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8
Q

What type of vaccine is the MMR?

A

Live attenuated vaccine

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9
Q

Describe the antenatal screening for rubella.

A
  • All pregnant women attending antenatal clinics are tested for immune status against rubella
  • Non-immune women should be offered the rubella vaccine in the immediate postpartum period
  • NOTE: the vaccine should not be given in pregnancy because it is a live vaccine
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10
Q

What is the definition of congenital CMV infection?

A

Detection of CMV from bodily fluids (normally urine and saliva) or tissues within the first 3 weeks of life

NOTE: it is the MOST COMMON congenital viral infection

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11
Q

What is the main consequence of congenital CMV infection?

A

Sensorineural hearing loss

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12
Q

At what stage in pregnancy does CMV infection pose a risk to the foetus?

A

At any stage in pregnancy

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13
Q

What is the term used to describe congenital changes that occur as a result of CMV infection? List some features.

A

Cytomegalic inclusion disease

  • CNS: microcephaly, mental retardation, epilepsy
  • Eye: chorioretinits
  • Ear: sensorineural deafness
  • Liver: hepatosplenomegaly, jaundice
  • Lung: pneumonitis
  • Heart: myocarditis
  • Thrombocytopaenic purpura
  • Haemolytic anaemia

NOTE: late sequelae include hearing defects and redued intelligence

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14
Q

What is the risk of CMV reinfection/reactivation compared to primary CMV infection to the foetus?

A

Low risk of foetal abnormalities

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15
Q

What proportion of cases of congenital CMV infection are asymptomatic at birth?

A

90%

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16
Q

Outline some tests used in the diagnosis of CMV infection.

A
  • Virus detection - cell culture, detection of early antigen fluorescent foci (DEAFF, CMV DNA (PCR)
  • Serology - IgG seroconversion, IgG avidity, IgM
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17
Q

Describe pre-natal diagnosis of suspected CMV infection.

A
  • Used to diagnose suspected intrauterine CMV infection
  • Detection of CMV DNA in amniotic fluid at 21 weeks gestation
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18
Q

How is congenital CMV infection treated?

A
  • There is NO vaccine
  • Congenital CMV with significant organ disease
    • Valganciclovir or ganciclovir for 6 months
    • Audiology follow-up until age 6 years
    • Ophthalmology review
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19
Q

List some factors affecting the transmission of HSV to the neonate.

A
  • Type of maternal infection (primary carries greatest risk)
  • Maternal antibody status
  • Duration of rupture of membranes
  • Integrity of mucocutaneous barriers (e.g. use of foetal scalp electrodes)
  • Mode of delivery (vaginal delivery in a mother with genital HSV puts the baby at increased risk - C-section would be recommended)
  • HSV infection at the latter end of pregnancy
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20
Q

In which scenario will the neonate be at highest risk of acquiring HSV from the mother?

A
  • Primary HSV infection in the 3rd trimester (particularly within 6 weeks of delivery)
  • C-section is recommended
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21
Q

Outline the manifestations of neonatal HSV disease.

A
  • Skin, eyes and mouth (SEM) disease
  • CNS disease with or without SEM
  • Disseminated infection involving multiple organs (high mortality)
22
Q

Describe the clinical presentation of intrauterine HSV infection.

A
  • Neurological - microcephaly, encephalomalacia, intracranial calcification
  • Cutaneous - scarring, active lesions
  • Ophthalmologic - microophthalmia, optic atrophy, chorioretinitis
23
Q

Outline the features of disseminated HSV infection.

A
  • DIC
  • Pneumonia
  • Hepatitis
  • CNS involvement
  • NOTE: has a 30% mortality
24
Q

Outline the manifestations of HSV encephalitis.

A
  • Seizures
  • Lethargy
  • Poor feeding
  • Temperature instability

NOTE: this tends to present late - 10-28 days

25
Q

List some approaches to improving outcomes in neonatal HSV infection.

A
  • Decrease time to diagnosis
  • Early antiviral therapy
  • Prompt collection of specimens
26
Q

Describe the treatment of neonatal HSV infection.

A
  • High-dose IV aciclovir (60 mg/kg/day) in three divided doses
  • For 21 days minimum in disseminated disease (repeat LP and CSF PCR until PCR-negative)
  • For 14 days minimum in SEM disease
  • Monitor neutrophil count
27
Q

What type of virus is VZV?

A

DNA virus of the herpes family

28
Q

What are the risks to the mother of VZV infection during pregnancy?

A

Pneumonia

Encephalitis

29
Q

What are the possible outcomes of intrauterine VZV infection?

A
  • Congenital varicella syndrome
  • Neonatal varicella
  • Herpes zoster during infancy or early childhood
30
Q

List the main features of congenital varicella syndrome.

A
  • LBW
  • Cutaneous scarring
  • Limb hypoplasia
  • Microcephaly
  • Chorioretinitis
  • Cataracts
31
Q

At what stage in pregnancy is the risk of congenital varicella syndrome highest?

A

13-20 weeks

NOTE: shingles has no risk in pregnancy

32
Q

During which time period is a newborn vulnerable to acquiring neonatal varicella infection?

A

If maternal infection occurs within 7 days before to 7 days after delivery

NOTE: there is not enough time for maternal antibodies to develop and be transferred

33
Q

Describe the manifestations of neonatal varicella infection.

A
  • Mild course
  • Disseminated skin lesions
  • Visceral infection
  • Pneumonia
34
Q

How can neonatal/congenital varicella be prevented?

A
  • Live virus vaccine (only pre-conception)
  • Avoidance of exposure in pregnancy
  • VZIG given within 10 days of exposure if gestation < 20 weeks
  • Antivirals if exposed
    • Aciclovir from day 7-14 post exposure
    • Tends to be used if >20 weeks and exposed
35
Q

What type of virus is measles?

A

RNA virus

36
Q

Describe the symptoms of measles.

A
  • Prodrome (2-4 days): fever, malaise, congestion, conjunctivitis, Kopolik spots
  • Maculopapular rash starting behind the ears and spreading across the body
37
Q

List some complications of measles.

A
  • Opportunistic bacterial infection (otitis media, pneumonia, bronchitis)
  • Encephalitis
  • Subacute sclerosing panencephalitis
    • Tends to occur 6-15 years after measles infection
    • Present with delays motor skills and behavioural problems
38
Q

What are the risks of measles in pregnancy?

A
  • Foetal loss (miscarriage, intrauterine death)
  • Preterm delivery
  • Increased maternal morbidity
  • IMPORTANT: NO congenital abnormalities to the foetus
39
Q

How should pregnant women who have been in contact with suspected/confirmed measles be treated?

A

Measles immunoglobulin attenuates the illness if given within 6 days of exposure

40
Q

What type of virus is parvovirus B19?

A
  • DNA virus
  • Parvoviridae family
41
Q

Describe the clinical presentation of parvovirus B19 infection.

A
  • Erythema inifectiosum (fifth disease, slapped cheeck syndrome)
  • Transient aplastic crisis
  • Arthralgia
  • Non-immune hydrops fetalis
42
Q

Outline the pathophysiology of parvovirus B19 infection.

A
  • Tropism for rapidly-dividing erythrocyte precursors
  • Causes suppression of erythrogenesis
  • NO reticulocytes are available to replace ageing or damaged arythrocytes as they are cleared by the reticuloendothelial system
43
Q

What does the virus require in order to infect red cell precursors?

A

P blood antigen receptor (globoside)

44
Q

Describe the pathophysiology of congenital parvovirus B19 infection.

A
  • Virus crosses the placenta and destroys foetal red blood cell precursors foetal anaemia → high-output congestive cardiac failure → hydrops fetalis
  • Virus can also directly damage myocardial cells
45
Q

At what stage in pregnancy is parvovirus B19 infection most concerning?

A

< 20 weeks gestation

46
Q

Describe how maternal parvovirus B19 infection can be diagnosed.

A
  • PCR - DNA amplification
  • Serology - parvovirus IgG seroconversion and IgM
  • Foetal infection - same tests
47
Q

How might parvovirus B19 infection in pregnancy be treated?

A
  • Intrauterine blood transfusion
  • Some will resolve spontaenously
  • If the foetus survives the hydropic state, they have a good prognosis
48
Q

Outline the symptoms of Zika virus.

A
  • 80% asymptomatic
  • May cause fever, rash, myalgia and arthralgia
49
Q

What are some consequences of Zika virus infection in pregnancy.

A
  • Miscarriage
  • Stillbirth
  • Congenital Zika syndrome
    • Severe microcephaly
    • Decreased brain tissue
    • Seizures
    • Retinopathy/deafness
    • Talipes
    • Hypertonia
50
Q

What advice can be given to pregnant women who are concerned about Zika virus?

A
  • Bite avoidance
  • Avoid travelling to Zika endemic countries if pregnant
  • Avoid conception 2-6 months after travel to Zika endemic country (6 months for men, 2 months for women)
  • Test only if symptomatic or abnormalities seen on USS

YEAR 5: Microbiology and Infection (24 decks)

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