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

MI: Viral Infections in Pregnancy Flashcards

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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 during labour)
  • Postnatally (from breast milk and other sources)
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2
Q

What are the potential viral causes of rashes during pregnancy?

A
  • VZV (chicken pox and shingles)
  • EBV
  • HSV
  • CMV
  • Parvovirus B19
  • Enterovirus
  • Measles
  • Rubella
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3
Q

What type of virus is rubella?

A
  • RNA virus
  • Togaviridae family
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4
Q

How is rubella transmitted?

A
  • Via respiratory droplets (therefore ISOLATE in suspected cases)
  • Virus replicates in lymphoid tissue of URT then spreads haematogenously
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5
Q

What are the symptoms of rubella infection?

A

20-50% subclinical

  • Prodrome (1-5 days pre rash) - coryza, sore throat, headache, low-grade fever
  • Fine macular rash - mildy pruritic, starts on face and spreads to trunk/limbs within hours
  • Lymphadenopathy - tender, postauricular/cervical/suboccipital
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6
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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7
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

If infected before 10 weeks, 90% incidence of foetal defects

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8
Q

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

A
  • Serology - IgG, IgM
  • Detection of virus (PCR) - blood, urine, tissues
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9
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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10
Q

What type of vaccine is the MMR?

A

Live attenuated vaccine

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11
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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12
Q

How is CMV transmitted?

A

Infectious bodily fluids: saliva, respiratory droplets, urine, blood, breastmilk

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13
Q

What are the main symptoms of CMV infection?

A

Largely asymptomatic

  • Maculopapular rash
  • Infectious mononucleosis-like illness
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14
Q

Describe the risk of transmission from primary vs non-primary infection

A
  • Primary infection - 30% transmit virus across placenta
  • Non-primary infection - 1% transmit virus across placenta

Non-primary infection far more common than primary infection due to high CMV seroprevalence rates

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15
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, ventriculomegaly, encephalitis, peri-ventricular calcifications
  • Eye - chorioretinitis
  • Ear - sensorineural deafness
  • Liver - hepatosplenomegaly, jaundice
  • Thrombocytopaenia

NOTE: late sequelae include hearing defects, mental retardation, and epilepsy

CMV associated with periventricular calcifications, whereas toxoplasmosis associated with diffuse intracranial calcifications

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16
Q

What is the risk of CMV non-primary compared to primary CMV infection to the foetus?

A

Lower risk of foetal abnormalities

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17
Q

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

A

90%

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18
Q

What is the most common neurodevelopment abnormality causes by congential CMV?

A

Sensorineural deafness

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19
Q

Outline some tests used in the diagnosis of CMV infection.

A
  • PCR of urine/saliva/amniotic fluid/tissue
  • Serology - IgG, IgM
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20
Q

How is suspected antenatal maternal CMV infection investigated?

A
  • If maternal CMV infection is suspected then check serology (compare booking to repeat sample)
  • If seroconversion suspected (i.e. infection during pregnancy) then refer to fetal medicine unit for USS +/- amniocentesis for CMV PCR
  • No treatment available
  • Neonates are investigated – urine and saliva CMV PCR within 1st 21 days.
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21
Q

Describe how foetal CMV infection is diagnosed

A

Amniotic fluid PCR at 21 weeks gestation

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22
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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23
Q

How are HSV 1 and 2 transmitted?
What are the incubation periods between oro-facial infection and genital infection?

A
  • Transmitted via direct contact with infected lesions
  • Oro-facial incubation - 2-12 days
  • Genital incubation - 4-7 days
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24
Q

What are the symptoms of HSV 1 and 2 infection?

A

Can be asymptomatic

  • Painful vesicular rash
  • Lymphadenopathy
  • Fever
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25
Q

What is the difference between primary, non-primary, and recurrent HSV infection?

A
  • Primary infection - first occurrence of gential HSV. No pre-existing HSV1 or HSV2 antibodies.
  • Non-primary infection - 1st episode of gential HSV but only has antibodies to the other HSV type
  • Recurrent infection - current HSV infection with pre-existing antibodies. Infection may previously have been asymptomatic or symptomatic.
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26
Q

How can HSV be transmitted to foetus and neonate?

A

Foetal infection - ascending infection in PROM

Neonatal infection:

  • Direct contact with infected secretions during delivery
  • Kiss baby with oral herpes
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27
Q

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

A
  • Type of maternal infection (primary infection 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
28
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
29
Q

How is HSV infection in pregnacy managed?

A
  • GUM referral
  • Aciclovir
  • Planned C-section if infection in the 3rd trimester
30
Q

How is recurrent HSV treated in pregancy?

A
  • May not treat
  • Consider daily suppressive aciclovir from 36 weeks
  • Avoid PROM and invasive foetal monitoring

In recurrent infection, maternal antibody will offer some protection (but may not prevent transmission)

31
Q

Outline the manifestations of neonatal HSV disease.

A
  • Skin, eyes, and mouth (SEM) - 45% of cases
  • CNS (+/- SEM) - 30% of cases
  • Disseminated infection (high mortality) - 25% of cases

If untreated, neonatal herpes has >80% mortality with severe neurological involvement

32
Q

How do SEM, CNS, and disseminated neonatal HSV infection present?

A
  • SEM (first 2 weeks)- oral and skin vesicles, keratoconjunctivitis
  • CNS (weeks 2-3) - seizures, lethargy, irritability, reduced feeding, fever, bulging fontanelle (requires CSF sample)
  • Disseminated (week 1) - presents like sepsis, multiorgan involvement (liver, lungs, CNS, heart, GI, renal, bone marrow)
33
Q

Describe the clinical presentation of intrauterine HSV infection.

A
  • Neurological - microcephaly, encephalomalacia, intracranial calcification
  • Cutaneous - scarring, active lesions
  • Ophthalmologic - microophthalmia, optic atrophy, chorioretinitis
34
Q

Outline the features of disseminated HSV infection.

A
  • DIC
  • Pneumonia
  • Hepatitis
  • CNS involvement

30% mortality rate even with treatment

35
Q

List some approaches to improving outcomes in neonatal HSV infection.

A
  • Decrease time to diagnosis
  • Early antiviral therapy
  • Prompt collection of specimens
36
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
37
Q

What type of virus is VZV? How is it transmitted?

A
  • DNA herpes virus
  • Transmitted via respiratory droplets (ISOLATE suspected cases)
38
Q

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

A
  • Pneumonia (10-20%)
  • Encephalitis (5-10% mortality rate)
39
Q

What are the possible outcomes of intrauterine VZV infection?

A
  • Congenital varicella syndrome
  • Neonatal varicella
  • Herpes zoster during infancy or early childhood
40
Q

List the main features of congenital varicella syndrome.

A
  • Low birth weight
  • Cutaneous scarring
  • Limb hypoplasia
  • Microcephaly
  • Chorioretinitis and cataracts
  • GORD
41
Q

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

A

12-20 weeks (2% risk)

NOTE: shingles has no risk in pregnancy

42
Q

During which time period of maternal infection 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

43
Q

Describe the manifestations of neonatal varicella infection.

A
  • Mild course
  • Disseminated skin lesions
  • Visceral infection
  • Pneumonia
44
Q

How is antenatal varicella exposure managed?

A
  • Check previous infection/vaccination status (if unsure, do VZV IgG serology)
  • Give VZIG ASAP (effective for up to 10 days post-exposure)
45
Q

How is antenatal VZV infection managed?

A

Oral aciclovir (IV if severe)

46
Q

What type of virus is measles? How is it transmitted?

A
  • RNA virus
  • Transmitted via respiratory droplets (ISOLATE), conjuctiva
47
Q

Describe the symptoms of measles.

A
  • Prodrome (2-4 days): fever, malaise, coryza,
  • Conjunctivitis
  • Kopolik spots
  • Maculopapular rash starting at hairline and spreading to trunk/limbs within 3 days
48
Q

List some maternal complications of measles infection.

A
  • Secondary bacterial infection (otitis media, pneumonia, bronchitis)
  • Encephalitis
  • Subacute sclerosing panencephalitis
49
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

50
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

51
Q

What type of virus is parvovirus B19?

A
  • DNA virus
  • Parvoviridae family
52
Q

Describe the clinical presentation of parvovirus B19 infection.

A

Mostly asymptomatic

  • Erythema infectiosum (fifth disease, slapped cheeck syndrome)
  • Transient aplastic crisis
  • Polyarthropathy
53
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 egeing or damaged arythrocytes as they are cleared by the reticuloendothelial system
54
Q

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

A

<20 weeks gestation

  • 33% risk of tranmission to foetus
  • 9% infection risk
  • 50% of foetal infections result in intrauterine death

Infection >20 weeks has no documented risks

55
Q

What is the main complication to the foetus from parvovirus B19 infection?

A
  • Viral destruction of erthrocyte precursors causes severe anaemia
  • This leads to high-output heart failure and hydrops fetalis
56
Q

How is parvovirus B19 infection <20 weeks managed?

A
  • Referral to fetal medicine for monitoring
  • May require intrauterine blood transfusion
  • Some will resolve spontaenously
  • If the foetus survives the hydropic state, they have a good prognosis
57
Q

Describe how maternal parvovirus B19 infection can be diagnosed.

A
  • Viral detection (PCR)
  • Serology
58
Q

Name some human pathogenic enteroviruses?
How can they be transmitted?

A

Transmitted via respiratory droplets +/- faecal

59
Q

What are the symptoms of enterovirus infection?

A
  • Hand, foot, mouth disease
  • Rash
  • Encephalitis
  • Myocarditis
60
Q

Which enterovirus presents the biggest risk to the neonate?

A

Coxsakie virus

  • Perinatal infection can occur in the last week of pregnancy
  • Neonates are at risk of myocarditis, fulminant hepatitis, bleeding, and multi-organ failure
61
Q

Outline the symptoms of Zika virus.

A
  • 80% asymptomatic
  • May cause fever, rash, myalgia and arthralgia
62
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
63
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
64
Q

What questions to ask pregnant women presenting with rashes in history?

A
65
Q

What is the general investigations to conduct in pregnant women with rashes?

A
66
Q

What is subacute sclerosing panencephalitis?

A
  • Fatal progressive degenerative disease
  • Tends to occur 7-10 years after measles infection
  • Present with delays motor skills and behavioural problems

YEAR 5: Microbiology and Infection PM (26 decks)

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