Toxoplasma gondii

Question 1

Screening? toxoplasmosis

Answer 1

Not routinely in Australia - pros and cons are complex

Question 2

Advice on prevention of toxo infection

Answer 2

1. Avoid raw / undercooked meat
2. Wash hands after gardening
3. Wash raw vegetables
4. Minimise contact with young kittens and their litter etc.

Question 3

Symptoms of toxoplasmosis

Answer 3

Malaise, fever, lymphadenopathy

Question 4

Toxoplasma IgM

Answer 4

Can remain +ve for months or years
Rising IgG level and/or low IgG avidity are more specific for “recent” infection (within 3 months)

Question 5

Past or recent toxo?

Aysmptomatic
Inconsistent/low +ve IgM
and/or
High IgG avidity (≤16 weeks)

Answer 5

Past toxo
No further action

Question 6

Past or recent toxo?

Symptoms and/or additional testing (repeat, avidity, antenatal specimen testing):
Repeat/high +ve IgM
Low IgG avidity

Answer 6

Recent toxo

Question 7

Risk of transmission and damage with toxo in first trimester

Answer 7

• Fetal infection low risk (4-15%)
• If infected, high risk of damage (34-84%), likely to be severe

Question 8

Risk of transmission and damage with toxo in second trimester

Answer 8

• Fetal infection intermediate risk (25-44%)
• If infected intermediate risk of damage (18-33%), likely to be less severe

Question 9

Risk of transmission and damage with toxo in third trimester

Answer 9

• Fetal infection high risk (30-75%)
• If infected low risk of damage (4-17%), usually asymptomatic at birth

Question 10

Treatment for toxo infection ≤18 weeks

Answer 10

Consider spiramycin to prevent vertical transmission (not routinely available in Australia.)
Does not cross placenta, no RCT evidence
Continue therapy until delivery

Question 11

Treatment for toxo infection ≥18 weeks or confirmed fetal infection

Answer 11

Pyrimethamine + sulfadiazine + folinic acid to treat fetus
Potentially toxic in first trimester

Question 12

Ultrasound findings in toxo (not specific)

Answer 12

Hydrocephalus
Brain or hepatic calcification
Ascites
Splenomegally

Question 13

Intrauterine diagnosis of fetal toxo

Answer 13

• Amnio + T. gondii PCR at 18-20 weeks gestation or 4 weeks post maternal infection (high sens and spec)
• Fetal US + MRI not diagnostic but can provide information

Question 14

Management of confirmed fetal toxo

Answer 14

Ultrasound for prognostic information
Treat mother with pyrimethamine + sulfadiazine + folinic acid
Confirm diagnosis in infant

Question 15

Symptoms of congenital toxoplasmosis

Answer 15

• chorioretinitis / retinal scarring
• intracranial calcification
• hydrocephalus
• hepatosplenomgealy
• pneumonia
• thrombocytopenia
• myocarditis