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Toxoplasma gondii PCR



Test performed by: LabPLUS VIM Molecular Diagnostics


Specimen Collection

A dedicated specimen (i.e. no other tests to be performed) is required for this assay.

Do not use heparin tubes

Do not separate blood tubes. Whole blood required. 

Do not freeze. Send chilled.


EDTA4 mL EDTA Whole Blood (Always Required)

Absolute minimum is 0.5mL

Acutely infected adult or immunocompromised patients 


Micro-EDTA0.5 mL Paediatric Micro-EDTA Whole Blood (Always Required)

Congenital infection 


Sterile Container0.5 mL Sterile Container CSF

Acutely infected adult or immunosuppressed patient: 


Sterile Container5 mL Sterile Container Amniotic Fluid

Intrauterine infection
5 mL of amniotic fluid. This is the optimal specimen for identification of intrauterine infection.

Congenital infection - newborn infant :

5 mL of amniotic fluid.  


Sterile Container1 Units Sterile Container Tissue

Acutely infected adult or immunosuppressed patient:
Tissue biopsy:  e.g. Lymph node, cardiac biopsy, brain biopsy, vitreous biopsy .

Congenital infection - newborn infant:
Fresh placental biopsy:  Note: Sampling error may occur, so multiple small samples are preferred. 


Turnaround Time:

 Tests performed as requested with results available within 4 days.


Assay Method

The current test for human T. gondii is real-time PCR assay targeting the 529-bp Repeat Element of the T. gondii genome.  

Lowest limit of detection: 180 copies/mL


Diagnostic Use and Interpretation

Toxoplasma gondii is a ubiquitous protozoan parasite infecting virtually any warm-blooded animal. The definitive hosts are cats which shed infectious sporozoites in faeces. In addition to infection from a contaminated environment, humans may acquire infection through eating toxoplasma cysts in undercooked meat, or vertically through the passage of tachyzoites across the placenta of a newly infected pregnant woman.

Infection in the immunocompetent human is usually trivial. In immunocompromised patients however toxoplasma is a major opportunistic pathogen causing life-threatening disease.   Likewise, intrauterine infection potentially causes significant foetal damage with brain defects, blindness or even death.

Diagnosis of acute infection is best achieved by PCR detection of toxoplasma DNA.   CSF, vitreous fluid, tissue biopsy, amniotic fluid and in some instances, EDTA blood,   are all appropriate specimens for PCR analysis.

Serology is less helpful since IgM antibodies may persist for months after initial infection.           

 

References.

1.         Udo Reischl, Stephane Bretange, Dominique Kruger et.al. Comparison of two DNA targets for the diagnosis of Toxoplasmosis by real time PCR using fluorescence resonance energy transfer hybridization probes. BMC Infect.Dis. 2003, 2;3(1):7


Contact Information

For further information contact the laboratory  (contact via Lablink: 22000 or (09) 307-8995 or 0800 522 7587) ,or:
the Virology team virology@adhb.govt.nz

 


Specimen Transport Instructions for Referring Laboratories

Do not freeze. Send chilled



Last updated at 13:33:21 23/09/2020