Acquired Toxoplasmosis in a 6-Year-Old Child
Clinical Presentation
In a previously healthy 6-year-old child, acquired toxoplasmosis most commonly presents as asymptomatic infection or with cervical lymphadenopathy and a mononucleosis-like syndrome, though most cases (70-90%) remain clinically silent. 1
Typical Manifestations
Cervical lymphadenopathy is the most common clinical finding when symptoms occur, often the presenting sign that brings the child to medical attention 1, 2
Constitutional symptoms include malaise, fever, sore throat, and myalgia—mimicking infectious mononucleosis 1
Mononucleosis-like syndrome may feature a maculopapular rash and hepatosplenomegaly 1
Neurologic complications are extremely rare in immunocompetent children but can include facial nerve palsy or other cranial neuropathies 3
Important Clinical Context
The available guidelines 1 focus heavily on HIV-infected children and congenital toxoplasmosis, but the key principle for immunocompetent children is that acquired infection after birth is usually benign and self-limited 1. The severe presentations (encephalitis, chorioretinitis) described in the guidelines primarily apply to immunocompromised patients or congenital infection, not to previously healthy 6-year-olds with acquired disease 1, 4.
Diagnostic Work-Up
Serologic testing is the primary diagnostic method, specifically looking for Toxoplasma-specific IgM and IgG antibodies to confirm acute infection. 1, 5
Essential Diagnostic Steps
Toxoplasma serology: Order IgM and IgG antibodies; positive IgM with rising IgG titers confirms acute infection 1, 5
Complete blood count: May show atypical lymphocytosis similar to infectious mononucleosis 6
Consider specialized reference laboratory if serologic interpretation is unclear, as these assays can be confusing and difficult to interpret 1, 5
Additional Testing Based on Clinical Findings
Ophthalmologic examination if any visual complaints, as isolated ocular toxoplasmosis can occur (though rare and usually associated with CNS involvement) 1, 4
Neurologic examination is mandatory if chorioretinitis is detected 1, 4
Brain MRI (more sensitive than CT) only if neurologic symptoms develop—fever, altered consciousness, seizures, or focal deficits 5, 4, 7
PCR for Toxoplasma DNA in blood can be performed at reference laboratories if diagnosis remains uncertain 3
Common Diagnostic Pitfall
Do not confuse this with congenital toxoplasmosis—the 6-year-old with acquired infection has a fundamentally different disease course and prognosis than infants with congenital infection described extensively in the guidelines 1, 4. The severe late sequelae (progressive retinitis, seizures, developmental delays) occur in congenital cases, not in immunocompetent children with acquired infection 1, 4.
Treatment Recommendations
For uncomplicated acquired toxoplasmosis in an immunocompetent 6-year-old presenting with lymphadenopathy alone, treatment is generally not required as the infection is self-limited. 6, 8
Treatment Algorithm
If symptomatic disease warrants treatment (persistent symptoms, severe adenopathy, or any neurologic/ocular involvement):
Pyrimethamine: 2 mg/kg/day for 3 days, then 1 mg/kg/day 5, 7
Leucovorin (folinic acid): 10-25 mg/day—must always be given with pyrimethamine to prevent bone marrow suppression 5, 7
Duration: Continue for at least 6 weeks if treating neurologic disease; 2 months for the case with facial nerve palsy reported in the literature 3
Monitoring: Weekly complete blood count while on daily pyrimethamine to detect bone marrow suppression 7
Alternative Regimen
- Pyrimethamine plus clindamycin if the child cannot tolerate sulfa drugs 5
Treatment Considerations
Most immunocompetent children with acquired toxoplasmosis and simple lymphadenopathy recover completely without specific antimicrobial therapy 6, 9, 8. The decision to treat should be based on:
- Severity and persistence of symptoms
- Presence of neurologic or ocular involvement
- Patient and family preference after discussing the self-limited nature of disease
The case reports demonstrate complete recovery even with treatment 3, 9, but also show spontaneous resolution without intervention in many cases 9.
Critical Caveat
Never give pyrimethamine without leucovorin—this combination is non-negotiable to prevent potentially severe hematologic toxicity 5, 7. Weekly CBC monitoring is mandatory during treatment 7.