Original Article
Journal of Perinatology (2009) 29, 668–672; doi:10.1038/jp.2009.79; published online 25 June 2009
Toxoplasmosis in pregnancy: determination of IgM, IgG and avidity in filter paper-embedded blood
I Cañedo-Solares1, L B Ortiz-Alegría1, R Figueroa-Damián2, M L Bustos-Bahena1,3, H González-Henkel1, E Calderón-Segura1, H Luna-Pastén1 and D Correa1
- 1Instituto Nacional de Pediatría, Secretaría de Salud, México DF, México
- 2Instituto Nacional de Perinatología, Secretaría de Salud, México DF, México
- 3Laboratorios Flemming SA de CV, Jojutla, Morelos, México
Correspondence: Dr D Correa, Lab. Inmunología Experimental Torre de Investigación Instituto Nacional de Pediatría, SSA Av. Insurgentes Sur 3700-C Col Insurgentes Cuicuilco México 04530 DF, México. E-mail: mariadol@yahoo.com or E-mail: mariadol@salud.gob.mx
Received 17 September 2008; Revised 29 March 2009; Accepted 8 April 2009; Published online 25 June 2009.
Abstract
Objective:
To detect immunoglobulin M (IgM) anti-Toxoplasma gondii antibodies and determine immunoglobulin G (IgG) titer and avidity in filter paper-embedded blood (FPEB) samples of pregnant women.
Study Design:
A total of 100 FPEB samples of pregnant women (30 positive and 70 negative) were analyzed for anti-T. gondii-specific IgM antibodies. Eleven and nine pairs of serum and FPEB samples were used to standardize IgG titration and avidity, respectively. Then, the correlation of avidity results was determined with 23 serum/FPEB pairs from IgG-positive cases.
Result:
IgM detection in FPEB was 92% sensitive and 100% specific. The titration of IgG antibodies in FPEB correlated with that of serum (r 
0.9). Significant difference in avidity between the acute and the undetermined/chronic cases was observed in both samples. As expected, no correlation was found between IgM levels and avidity.
Conclusion:
The FPEB is useful to infer infection phase, and thus to speed clinical decisions in congenital toxoplasmosis management.
Keywords:
avidity, IgM, IgG, newborns, paper filter-embedded blood, pregnant women
