1. Toxoplasma gondii in the peripheral blood of patients with acute and chronic toxoplasmosis
Br J Ophthalmol 2011;95:396e400
R2 유영식/AP.박영훈

2. INTRODUCTION Toxoplasma gondii Toxoplasmic retinochoroiditis
Obligate intracellular protozoan parasite
Important causative agent of human infection
In the immunocompetent host
Asymptomatic
Severe symptoms such as uveitis, pneumonia, pericarditis, myositis and neurological disorders
Toxoplasmic retinochoroiditis
Rupture of cysts can release viable parasites
Induce necrosis and inflammation

3. INTRODUCTION Recurrences of ocular lesions
Usually develop at the border of old scars
Rupture of tissue cysts located within the old lesions
Triggered by changes in the parasite metabolism or by the host immune response
Transmission of parasitic infection
A new active infection may be caused
by previous lesions in the brain or eyes
by reinfection
To investigate whether or not T gondii is present in blood of patients
From peripheral blood mononuclear cells (PBMC)

4. METHODS Study population All samples were blindly analysed
20 subjects from Erechim, Southern Brazil
Mean age : 39 years (range 12 ~ 68 years)
Classified into five groups – 실험군 16 (Group 1~4), 대조군 4 (Group 5)
Based on serological test results and on presence or absence of retinal lesions

5. METHODS Detection of T. gondii by light microscopy
Peripheral blood was obtained from the 28 subjects
Blindly evaluated in the laboratory
Detection of T. gondii by immunofluorescence
To detect the presence of T gondii in peripheral blood smears
Using polyclonal IgG antibody from T gondii-infected patients
Detection of T. gondii by PCR
T. gondii infections were confirmed by nested PCR
Amplification of the 5’ end of the polymorphic marker of parasite SAG2 gene

6. METHODS Infection of immunodeficient mice with PBMC from patients
1 : acute infection with T gondii.
3 : acute infection with T gondii.
Injected in the peritoneal cavity of 6-week-old male athymic nude mice
brains and eyes were processed for histological examination on H&E staining

7. RESULTS
Tachyzoite-like organisms were found in blood samples of 16 patients
nine patients, organisms were
detected using light microscopy (LM), whereas in seven the
immunofluorescency assay (IF) was used (table 1).

8. nine patients, organisms were
detected using light microscopy (LM), whereas in seven the
immunofluorescency assay (IF) was used (table 1).

9. RESULTS
Tachyzoite-like organisms were found in blood samples of 16 patients
Either free tachyzoites and intracellular tachyzoites, or both,
were observed by IF in peripheral blood smears from one of
the two patients who had been recently infected (Group 1)
(figure 1).
LM (figure 2) detected free tachyzoites in the same
patients.

10. RESULTS
Tachyzoite-like organisms were found in blood samples of 16 patients
Seven of the eight chronically infected patients with
recurrent retinochoroiditis (Group 2) had positive samples by
IF, whereas one of them had a sample with no detectable
parasite by LM.

11. RESULTS
Tachyzoite-like organisms were found in blood samples of 16 patients
Of the three chronically infected individuals
without retinal lesions (Group 4), one had a positive sample
only by IF. In two cases, IF detected a positive signal, whereas
LM did not.

12. RESULTS For visual detection
11 of the 16 infected patients was analysed (68.8%)
Confirm the presence of the parasite by PCR
In all positive sample detected by IF, except for one patient (patient 3)
Three of the samples indicated as negative by both LM and IF (patients 2, 13 and 15)
Group 1 (IgM positive) with inactive lesions
Group 3 (IgG positive) with inactive lesions & scar(+)
Group 4 (IgG positive) with inactive lesions
nine patients, organisms were
detected using light microscopy (LM), whereas in seven the
immunofluorescency assay (IF) was used (table 1).

13. RESULTS PBMCs from patients 1, 4, 7 and 10
Inoculated to intraperitoneal area in mice
The cyst observed in the brains of mice
nine patients, organisms were
detected using light microscopy (LM), whereas in seven the
immunofluorescency assay (IF) was used (table 1).

14. DISCUSSION Tachyzoites have been isolated
From the blood of immunocompetent patients with ocular disease
Not from the blood of patients with recurrent retinochoroiditis
With chronic infection and active ocular lesions
Not in the blood of patients without active lesions
Parasitaemia is associated with ongoing disease
nine patients, organisms were
detected using light microscopy (LM), whereas in seven the
immunofluorescency assay (IF) was used (table 1).

15. DISCUSSION
The presence of tachyzoites in the blood of patients with recurrent disease
Active parasites are important in the pathogenesis of ocular disease
For treatment
Secondary prophylaxis may reduce the rate of recurrences in some patients
Protective action of the association of sulfamethoxazole with trimetoprim to avoid recurrence

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