Assessment of the value of detecting specific IgA antibodies for the diagnosis of a recently acquired primary Toxoplasma infection.
OBJECTIVE
To assess the value of detecting IgA antibodies for the diagnosis of a recently acquired primary Toxoplasma infection.


METHODS
IgA antibodies were screened in sera from 87 women with different serological profiles of Toxoplasma gondii IgM and IgG antibodies and Toxoplasma-specific IgG avidity. The IgM and IgG antibodies and the IgG avidity were measured with an automated Vitek Immuno Diagnostic Assay System (VIDAS). Anti-T.gondii IgA was measured with Platelia Toxo IgA TMB kits.


RESULTS
All 12 sera obtained from women with clinical and/or serological evidence of a recently acquired Toxoplasma infection were positive for IgA. In 42 serum samples obtained more than 6 months after T. gondii infection from women with no clinical evidence of infection, but who had a positive IgM test and a high IgG avidity index, the IgA-enzyme linked immunosorbent assay (ELISA) test results were positive, negative, and doubtful in 16 (38.1%), 23 (54.8%), and 3 (7.1%) sera, respectively. In eight women, IgA was detected in sera collected more than 9 months after the onset of infection. The IgA test result was also positive in 11 of 12 sera (91.7%) obtained from women with no clinical evidence of toxoplasmosis, but who had a positive IgM test and a borderline IgG avidity index. The IgA-ELISA was negative in 21 sera obtained more than 2 years after the onset of T. gondii infection from women with no clinical evidence of toxoplasmosis, but who had a negative IgM test and a positive IgG test.


CONCLUSIONS
These results show that IgA is not a dependable marker for a recently acquired primary Toxoplasma infection.
Nascimento
Fernanda Santos
FS
Department of Clinical Pathology, Faculty of Medical Sciences, University of Campinas, Campinas, São Paulo, Brazil.
Suzuki
Lisandra Akemi
LA
Rossi
Cláudio Lúcio
CL
D000293:Adolescent; D000328:Adult; D000818:Animals; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood*; D013997:Time Factors; D014122:Toxoplasma / Q000276:immunology*; D014123:Toxoplasmosis / Q000097:blood / Q000175:diagnosis* / Q000276:immunology
D007070:Immunoglobulin A