Toxoplasmosis in pregnancy: Difference between revisions

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(Created page with "== Management == {| class="wikitable" !IgG !IgM !Interpretation !Management |- |– |– |no prior infection; at risk |counsel on prevention of primary infection (handwashing...")
 
(moved relevant contents from congenital infection)
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== Management ==
 +
== Clinical Manifestations ==
  +
  +
* Often no history of illness during pregnancy
  +
* Symptoms, if present, tend to be mild with low-grade fever, malaise, and lymphadenopathy
  +
  +
== Diagnosis ==
  +
  +
*Molecular
  +
**Definitive diagnosis is based on PCR of amniotic fluid around 18 months, usually done after maternal serology to confirm intrauterine infection
  +
***Sensitivity is 64 to 92% and specificity 100% (NPR around 88 to 98%)
  +
***Earlier than 18 weeks has unknown sensitivity and specificity, and has a higher risk of spontaneous abortion
  +
**Can also be done on fetal blood
  +
*Serology
  +
**Can check maternal IgM and IgG
  +
**IgM is not specific to recent infection, however, as it can be present for more than a year
  +
**IgG avidity testing is used to determine recency of infection
  +
***Low avidity is 35-50% and high is >60%
  +
***Low avidity is unhelpful, as avidity can remain low for more than a year
  +
***High avidity, on the other hand, suggests infected at least 3-4 months prior
  +
**Therefore, if infection is suspected in the first 16 weeks of gestation, avidity testing may be able to rule out infection during pregnancy
  +
*Needs serial head ultrasound to monitor for hydrocephalus and intraparenchymal brain calcifications
  +
**May also see hepatic calcifications, splenomegaly, and ascites
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  +
==Management==
 
{| class="wikitable"
  
{| class="wikitable"
 
!IgG
  
!IgG
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|–
  
|–
 
|no prior infection; at risk
  
|no prior infection; at risk
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|counsel on prevention of primary infection (handwashing after litter, cook meat well, no raw eggs or unpasteurized dairy
 +
|counsel on prevention of primary infection
 
|-
  
|-
 
|–
  
|–
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|}
  
|}
   
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=== Acute Infection ===
 +
===Acute Infection===
  +
  ⚫
*If acute infection, such as IgM + / IgG – that converts to IgG +, or IgM + / low IgG avidity with compatible clinical picture, then rule out fetal infection with an mmniocentesis after week 18
  +
*If infected < 14 weeks gestation, [[Is treated by::spiramycin]] 3 g/day until delivery
  +
**However, it doesn't cross the placenta and it's unclear whether it affects outcomes in the baby
  +
**Likely most effective if given within 8 weeks of maternal infection
  +
**Second-line would be monotherapy with [[Is treated by::sulfadiazine]] or [[Is treated by::clindamycin]]
  +
*If age ≥ 14 weeks gestation and documented fetal infection by amniocentesis, or if suspected infection was ≥14 weeks gestation, use standard therapy
  +
**Standard therapy is: [[Is treated by::pyrimethamine]] 50 mg q12h for 2 days followed by 50 mg daily (plus [[folinic acid]] 10-20 mg daily until 1 week after stopping pyrimethamine), and [[Is treated by::sulfadiazine]] 75 mg/kg load followed by 50 mg/kg q12h (maximum 4 g/day)
  +
**This treatment crosses the placenta, which is why it is used in cases of documented or suspected fetal infection, as well as in later-term infections when the risk of fetal infection is higher
  +
**Therefore, if initially started on [[spiramycin]], then switch to standard therapy if amniotic fluid PCR is positive or ultrasound is abnormal
  ⚫
**However, it is teratogenic until 14 weeks gestation so [[spiramycin]] is used until then
  +
  +
=== Prevention ===
   
  +
* Prevention mostly focusses on counselling around risk reduction:
⚫
* If acute infection, such as IgM + / IgG – that converts to IgG +, or IgM + / low IgG avidity with compatible clinical picture
  
−
** Amniocentesis after week 18
 +
** Wash hands after changing cat litter
  +
** Cook meat thoroughly
−
*** If PCR positive, treat with [[pyrimethamine]] and [[sulfadiazine]] plus [[folinic acid]], until delivery
  
  +
** Avoid raw eggs and unpasteurized dairy
−
*** If PCR negative, continue prophylaxis with [[spiramycin]] 1 g po TID
  
−
* Choice of antiparasitic
  
−
** [[Spiramycin]] does not cross the placenta, while [[pyrimethamine]] and [[sulfadiazine]] do
  
⚫
** However, [[pyrimethamine]] is teratogenic before 14 weeks gestation
  
   
 
[[Category:Infectious diseases]]
  
[[Category:Infectious diseases]]

Revision as of 13:13, 30 July 2020

Clinical Manifestations

  • Often no history of illness during pregnancy
  • Symptoms, if present, tend to be mild with low-grade fever, malaise, and lymphadenopathy

Diagnosis

  • Molecular
    • Definitive diagnosis is based on PCR of amniotic fluid around 18 months, usually done after maternal serology to confirm intrauterine infection
      • Sensitivity is 64 to 92% and specificity 100% (NPR around 88 to 98%)
      • Earlier than 18 weeks has unknown sensitivity and specificity, and has a higher risk of spontaneous abortion
    • Can also be done on fetal blood
  • Serology
    • Can check maternal IgM and IgG
    • IgM is not specific to recent infection, however, as it can be present for more than a year
    • IgG avidity testing is used to determine recency of infection
      • Low avidity is 35-50% and high is >60%
      • Low avidity is unhelpful, as avidity can remain low for more than a year
      • High avidity, on the other hand, suggests infected at least 3-4 months prior
    • Therefore, if infection is suspected in the first 16 weeks of gestation, avidity testing may be able to rule out infection during pregnancy
  • Needs serial head ultrasound to monitor for hydrocephalus and intraparenchymal brain calcifications
    • May also see hepatic calcifications, splenomegaly, and ascites

Management

IgG IgM Interpretation Management
– – no prior infection; at risk counsel on prevention of primary infection
– + acute primary infection or false positive repeat serology in 2 to 3 weeks; if unchanged, then was false positive
+ – prior infection no risk of transmission except rare cases of immunocompromise
+ + recent or prior infection do avidity testing: if high avidity, infection was >4 months ago so unlikely to be acute; if low avidity, uncertain

Acute Infection

  • If acute infection, such as IgM + / IgG – that converts to IgG +, or IgM + / low IgG avidity with compatible clinical picture, then rule out fetal infection with an mmniocentesis after week 18
  • If infected < 14 weeks gestation, spiramycin 3 g/day until delivery
    • However, it doesn't cross the placenta and it's unclear whether it affects outcomes in the baby
    • Likely most effective if given within 8 weeks of maternal infection
    • Second-line would be monotherapy with sulfadiazine or clindamycin
  • If age ≥ 14 weeks gestation and documented fetal infection by amniocentesis, or if suspected infection was ≥14 weeks gestation, use standard therapy
    • Standard therapy is: pyrimethamine 50 mg q12h for 2 days followed by 50 mg daily (plus folinic acid 10-20 mg daily until 1 week after stopping pyrimethamine), and sulfadiazine 75 mg/kg load followed by 50 mg/kg q12h (maximum 4 g/day)
    • This treatment crosses the placenta, which is why it is used in cases of documented or suspected fetal infection, as well as in later-term infections when the risk of fetal infection is higher
    • Therefore, if initially started on spiramycin, then switch to standard therapy if amniotic fluid PCR is positive or ultrasound is abnormal
    • However, it is teratogenic until 14 weeks gestation so spiramycin is used until then

Prevention

  • Prevention mostly focusses on counselling around risk reduction:
    • Wash hands after changing cat litter
    • Cook meat thoroughly
    • Avoid raw eggs and unpasteurized dairy

References

  1. ^  K. Boyer, D. Hill, E. Mui, K. Wroblewski, T. Karrison, J. P. Dubey, M. Sautter, A. G. Noble, S. Withers, C. Swisher, P. Heydemann, T. Hosten, J. Babiarz, D. Lee, P. Meier, R. McLeod. Unrecognized Ingestion of Toxoplasma gondii Oocysts Leads to Congenital Toxoplasmosis and Causes Epidemics in North America. Clinical Infectious Diseases. 2011;53(11):1081-1089. doi:10.1093/cid/cir667.

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