Toxoplasmosis

Question 1

Define

Answer 1

Protozoon toxoplasma gondii (parasite excreted in cat faeces, incubation period of 5-23 days)

• Transmission is faeco-oral route (from infected meat and cat faeces)
• Increased risk of vertical transmission with increasing gestational age (5% 1st, 80% 3rd trimester)
  
  • Infection in 1st trimester- most likely to cause foetal damage but transmission rate is LOW (10%)
  • In 3rd trimester- risk of foetal damage is low (10%) but transmission MUCH higher (85%)

Risk of congenital toxoplasmosis reduced with increasing gestational age (60-80% 1st, 5% 3rd)

Risk factors – household cats, increased incidence in rural areas and in France

Question 2

Signs and Symptoms

Answer 2

Mother: often asymptomatic fever, malaise, arthralgia

Child:

• 60% asymptomatic at birth; may develop… deafness, low IQ, microcephaly
• 40% symptomatic at birth… CLASSIC TRIAD/ ‘the 4 C’s of toxoplasmosis’:

1. Chorioretinitis
2. Convulsions
3. Hydrocephalus (microcephaly) Hepatosplenomegaly/jaundice
4. Intracranial (‘tram-like’) calcifications

• Scattered throughout the brain (unlike CMV, which is peri-ventricular)

Question 3

Investigations

Answer 3

NOT USUALLY SCREENED - as very unlikely for babies to be affected

Sabin Feldman Dye Test

Bloods – IgM (active – may persist for months/years after), IgG (immunity)

USS – foetal anomaly scan

Other – amniocentesis and PCR to detect foetal infection (done if USS raises suspicion)

Question 4

Management

Answer 4

(mother should avoid eating raw/rare meat and handling cats and cat litter)

 

Toxoplasmosis PCR +ve in mother, -ve in baby  Spiramycin (3-week course, 2-3g/day)

• I.E. no vertical transmission
• Spiramycin prevents vertical transmission - Can be given < 20 weeks gestation and can be continued throughout pregnancy if no evidence of transmission to foetus

  Toxoplasmosis PCR +ve in mother, +ve in baby  Pyrimethamine + Sulfadiazine + calcium folinate

• If foetal transmission is found < 20 weeks, give sulfadiazine alone until 20 weeks, and then add pyrimethamine and calcium folinate
• Treat baby for up to 1 year after delivery (if no TOP)
• Adjunct: Prednisolone

Question 5

Complications

Answer 5

miscarriage