TORCH group of infections - Toxoplasmosis

Toxoplasmosis, rubella, cytomegalovirus and herpes simplex viruses are collective called as TORCH group of infections.

These are important infections that should be ruled out in pregnancy because they can cause congenital malformations.

Toxoplasmosis

Causative organism:  Toxoplasma gondii

Transmission :

-Through encysted organisms by eating infected raw or uncooked beef or  pork.

-Through contact with oocytes in infected cat feces.

-The fetus can get infected by transplacental route.

  Usually fetus will be protected by maternal immunity. So if the women get infection  during the pregnancy the fetus can get affected.

Incidence:

Incidence of new infection in pregnancy is 0.5 to 8.1/1000.

Symptoms of maternal infection:

-Usually the infection will remain sunclinical.

-Some women may present with features like:

  Fatigue

  Muscle pains

  Fever

  Chills

  Maculopapular rash

  Lymphadenopathy etc.

-Infection can result in abortion or live baby with evidence of disease.

Effect on the fetus:

-The possibility and severity of the congenital infection depends on the gestational age when the fetus acquired it.

-With progression of pregnancy the risk of fetal infection increases but severity decreases.

-Generally less than 25% of congenital toxoplasmosis infected newborns will have clinical illness at birth. But later most of the children can show some sequelae of infection. So follow-up is needed.

-Clinically affected infants at birth can present with:

   Evidence of generalized disease

   Low birth weight

   Hepatosplenomegaly

   Icterus

   Anemia

-Some infants can have neurological sequelae also, like:

  Convulsions

  Intracranial calcifications

 Mental retardation

 Hydrocephaly or microcephaly.

-All most all infected infants develop chorioretenitis.

Treatment:

-Routine screening is not recommended in general.

But in women with HIV infection screening should be done.

-In women with active toxoplasmosis (IgM positive) antimicrobial treatment should be given.

Spiramycin, a macrolide antibiotic is usually used. Which reduces the incidence of fetal infection but it may not modify its severity.

Pyrimethamine plus sulfadiazine can also be used when the fetus is infected.

The usual followed protocol is:

If the pregnant suspected or confirmed of toxoplasmosis during gestation:

-In less than 18 weeks – spiramycin therapy and fetal ultrasound are adviced.

 Amniotic fluid PCR should be done after 18 weeks.

If PCR and ultrasound show negative results the spiramycin therapy(1 g, thrice a day ttill deleivery) can be continued.

Or if PCR and/or ultrasound show positive result combination therapy with pyrimethamin is preferred.

-In more than 18 weeks gestation: combination therapy with pyrimethamin is preferred.

 Ultrasound and amniotic fluid PCR should be done.

Pyrimethamin combination therapy is:

Pyrimethamin - 50mg, twice a day for two days. Followed by 50mg, once a day till delivery.

Sulfadiazine- 75mg/kg body weight, twice a day for 2 days. Followed by 50mg/kg body weight, twice a day till delivery.

Folinic acid- 10 to 20mg/day.

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