What are the symptoms, diagnosis, and treatment options for toxoplasmosis?

Symptoms, Diagnosis, and Treatment of Toxoplasmosis

Toxoplasmosis requires prompt diagnosis and treatment with pyrimethamine plus sulfadiazine and folinic acid for 12 months in confirmed cases to prevent serious complications including ocular disease, neurological damage, and death. 1, 2

Clinical Presentation

Symptoms

• Most infections in immunocompetent individuals are asymptomatic 3
• When symptomatic, common manifestations include:
  • Cervical lymphadenopathy 3
  • Flu-like symptoms (fever, fatigue, muscle aches) 3
  • Ocular disease (blurred vision, eye pain, photophobia) 4
• In immunocompromised patients:
  • Encephalitis (headache, confusion, seizures, focal neurological deficits) 3, 5
  • Pneumonitis 5
  • Myocarditis 3
• In congenital toxoplasmosis:
  • Intracranial calcifications 1
  • Hydrocephalus 1
  • Chorioretinitis 1
  • Hepatosplenomegaly 1

Diagnostic Approach

Serologic Testing

• Toxoplasma IgG and IgM antibodies are the first-line tests 1
• Positive IgM with rising IgG titers suggests acute infection 1
• In infants, persistence of IgG beyond 12 months of age confirms congenital toxoplasmosis 1
• Serial IgG testing every 4-6 weeks to document appropriate decrease or persistence 1

Molecular Testing

• PCR testing of:
  • Blood 1
  • Cerebrospinal fluid (CSF) 1
  • Amniotic fluid (in pregnant women) 6
  • Urine 1

Imaging Studies

• Head CT or MRI to evaluate for:
  • Intracranial calcifications 1
  • Ventriculomegaly 1
  • Hydrocephalus 1
• Abdominal ultrasound to assess for:
  • Hepatosplenomegaly 1
  • Intrahepatic calcifications 1

Ophthalmologic Examination

• Comprehensive retinal examination by a specialist 1
• Look for active chorioretinitis or characteristic retinal scars 1, 4

Treatment

Immunocompetent Patients with Acute Infection

• For mild to moderate disease:
  • Pyrimethamine plus sulfadiazine plus folinic acid for 2-4 weeks 1, 2
  • Pyrimethamine: 2 mg/kg/day orally divided twice daily for first 2 days, then 1 mg/kg/day 1
  • Sulfadiazine: 100 mg/kg/day orally divided twice daily 1
  • Folinic acid (leucovorin): 10 mg three times weekly 1, 2

Congenital Toxoplasmosis

• Treatment for 12 months with: 1
  • Pyrimethamine: 2 mg/kg/day orally divided twice daily for first 2 days; then 1 mg/kg/day daily for 2-6 months (longer for symptomatic cases); then 1 mg/kg/day three times weekly 1
  • Sulfadiazine: 100 mg/kg/day orally divided twice daily 1
  • Folinic acid: 10 mg three times weekly 1
• For severe chorioretinitis or elevated CSF protein (≥1 g/dL):
  • Add corticosteroids after 72 hours of anti-Toxoplasma therapy 1

Immunocompromised Patients

• Higher doses and longer duration of therapy may be required 3, 5
• Maintenance therapy may be necessary in severely immunocompromised patients 3

Ocular Toxoplasmosis

• Same regimen as for acute infection 4
• Duration typically 4-6 weeks depending on clinical response 4
• Consider corticosteroids for severe inflammation (only after 72 hours of anti-Toxoplasma therapy) 1, 4

Monitoring During Treatment

• Complete blood count with platelets at least twice weekly due to risk of bone marrow suppression 2
• Liver function tests periodically 2
• For congenital toxoplasmosis: 1
  • Physical examination every 2-3 months during first year, then every 4-6 months
  • Neurologic evaluation on same schedule
  • Ophthalmologic examination every 3-4 months during first year, then every 4-6 months
  • Auditory brainstem responses shortly after birth and yearly for first 3 years

Prevention

• Avoid consumption of undercooked meat 7
• Wash hands after gardening or contact with soil 7
• Wash fruits and vegetables thoroughly 7
• Avoid drinking untreated water 7
• Pregnant women should avoid changing cat litter or have someone else do it 6, 7
• If changing cat litter is unavoidable, wear gloves and wash hands thoroughly afterward 6

Special Considerations

Pregnancy

• Spiramycin should be offered for fetal prophylaxis if maternal infection is confirmed but fetal infection is not yet known 6
• If fetal infection is confirmed, switch to pyrimethamine, sulfadiazine, and folinic acid after first trimester 6
• Pyrimethamine is teratogenic and should be avoided in first trimester 2, 6

Immunocompromised Patients

• Higher risk of severe disease, including encephalitis 3, 5
• May require lifelong suppressive therapy 3
• HIV-positive patients should be screened due to risk of reactivation 6