Toxoplasmosis in Pregnancy

Question 1

How is Toxoplasma spread

Answer 1

• Contact with contaminated meat
• Contact with cat faeces

Question 2

Prevention of Toxoplasmosis

Answer 2

• Freeze meat for several days prior to cooking
• Cook food to safe temperatures
• Wash cutting boards, counters, hands with hot, soapy water
• Avoid untreated fresh water, unpasteurised dairy
• Wear gloves when gardening and practice hand hygiene
• Minimise contact with cats and kittens
• Feed cats canned or dried food (not fresh meat)
• Avoid changing cat litter, or if not possible use gloves
• Change litter daily

Question 3

Diagnosis

Answer 3

• Routine antenatal screening not recommended in Australia
• 50% of the population are susceptible
• Incidence of infection in pregnancy: 2/1000
• Cumulative incidence of congenital toxo 3.4/100 000 LB
• History
  o Usually asymptomatic infection
  o May have vague symptoms such as malaise, fever, headache, myalgias
• Examination
  o Cervical lymphadenopathy occurs in 7%
• Investigations
  o Diagnosis of an acute infection in pregnancy can be complex
  o Repeat serology in 2 weeks after initial to confirm diagnosis
  o Toxoplasma serology
• IgG – IgM –
• No past infection, at risk
• Education on prevention of exposure
• IgG + IgM –
• Past infection, no further action required
• IgM +ve IgG +/-
• IgM may remain positive for 10-13 months
• Most reliable diagnostic test is seroconversion of IgG during pregnancy
  o Check paired booking serology
• IgG avidity can be performed but unreliable
• High IgM titres or rising IgG titres are suggestive of infection
• Fetal transmission increases with increasing GA at seroconversion
  <4w: <1%
  13w: 4-15%
  36w: >60%

Risk of congenital abnormality inversely related to GA at seroconversion
- Greatest severity in T1
- Highest risk 13-28 weeks

Question 4

Neonatal sequelae

Answer 4

• mainly affects CNS and eyes
  microcephaly
  ventriculomegaly
  hydrocephalus, intracranial calcifications
  chorioretinitis, retinal scarring

Other:
* Pneumonia
* Thrombocytopaenia
* Myocarditis

Can affect any organ:
HSM
anaemia
rash
jaundice

Question 5

Sequelae in childhood

Answer 5

• Learning difficulty
• Convulsion and spasticity
• chorioretinitis and blindness

Question 6

Management

Answer 6

• Counsel re fetal risks
  o First trimester infection
• Low risk fetal infection 10%
• High risk of fetal damage 70%, likely severe
  o Second trimester infection
• Intermediate risk of infection 25%
• Intermediate risk of fetal damage 25%
  o Third trimester infection
• High risk of fetal infection 70%
• Low risk of fetal damage 10%, usually asymptomatic at birth
• Treat mother
  Depends on gestation and whether fetal infection confirmed
  DW ID
• Diagnosis of fetal infection
  o Ultrasound >4-6/52 after infection
• Hydrocephalus, brain/hepatic calcification, ascites, splenomegaly
• Non-specific
  o Amniocentesis
• Perform >=4 weeks after maternal infection or at 18-20/40
• T gondii PCR highly sensitive and specific
• Management in utero
  o Can be reassured if USS –ve and PCR –ve
• Continue maternal treatment if infection certain
  o If PCR +ve
• Consider termination
• Continue treatment
  o If USS abnormal
• Consider termination
• Management after delivery
  o Paediatric referral
  o Full clinical examination and imaging
• Audiology, ophthalmology, cerebral imaging
  o Investigations
• Blood serology
• Placental histology and T gondii PCR
• Blood and CSF PCR
• FBE
  o Treat infant if infection confirmed
  o Otherwise follow-up serology