MI: Viral Infections in Pregnancy Pt.1

Question 1

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

Answer 1

• In utero
• Perinatally (from vaginal secretions and blood during labour)
• Postnatally (from breast milk and other sources)

Question 2

What are the potential viral causes of rashes during pregnancy?

Answer 2

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

Question 3

What type of virus is rubella?

Answer 3

• RNA virus
• Togaviridae family

Question 4

How is rubella transmitted?

Answer 4

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

Question 5

What are the symptoms of rubella infection?

Answer 5

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

Question 6

What is the classic triad of congenital rubella syndrome?

Answer 6

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

Question 7

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

Answer 7

• 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

Question 8

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

Answer 8

• Serology - IgG, IgM
• Detection of virus (PCR) - blood, urine, tissues

Question 9

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

Answer 9

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

Question 10

What type of vaccine is the MMR?

Answer 10

Live attenuated vaccine

Question 11

What is the definition of congenital CMV infection?

Answer 11

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

Question 12

How is CMV transmitted?

Answer 12

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

Question 13

What are the main symptoms of CMV infection?

Answer 13

Largely asymptomatic

• Maculopapular rash
• Infectious mononucleosis-like illness

Question 14

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

Answer 14

• 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

Question 15

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

Answer 15

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

Question 16

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

Answer 16

Lower risk of foetal abnormalities

Question 17

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

Answer 17

90%

Question 18

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

Answer 18

Sensorineural deafness

Question 19

Outline some tests used in the diagnosis of CMV infection.

Answer 19

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

Question 20

How is suspected antenatal maternal CMV infection investigated?

Answer 20

• 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.

Question 21

Describe how foetal CMV infection is diagnosed

Answer 21

Amniotic fluid PCR at 21 weeks gestation

Question 22

How is congenital CMV infection treated?

Answer 22

• 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

Question 23

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

Answer 23

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

Question 24

What are the symptoms of HSV 1 and 2 infection?

Answer 24

Can be asymptomatic

• Painful vesicular rash
• Lymphadenopathy
• Fever

Question 25

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

Answer 25

• 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.

Question 26

How can HSV be transmitted to foetus and neonate?

Answer 26

Foetal infection - ascending infection in PROM

Neonatal infection:

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