Early neonatal diagnosis of congenital toxoplasmosis: value of comparative enzyme-linked immunofiltration assay immunological profiles and anti-Toxoplasma gondii immunoglobulin M (IgM) or IgA immunocapture and implications for postnatal therapeutic strategies.
Diagnostic strategies for congenital toxoplasmosis have changed profoundly in recent years. Immunological diagnostic methods, long considered disappointing, can now be used at a very early stage. Over a 3-year period, 1,050 infants at risk of congenital toxoplasmosis (born to 1,048 mothers infected during pregnancy) were monitored for a minimum of 12 months and a maximum of 7 years. More than 6,000 serum specimens were analyzed by comparative mother-infant immunological profiles (CIPs) based on an enzyme-linked immunofiltration assay (ELIFA) and an immunocapture method for the detection of specific immunoglobulin M (IgM) and IgA. IgG antibodies were also titrated. One hundred three cases of congenital toxoplasmosis were demonstrated. The CIP-ELIFA method had a better diagnostic yield (sensitivity, 90%) than specific IgM and/or IgA detection by immunocapture assay (sensitivity, 77%). By using a combination of these tests, congenital infection was diagnosed in the first month and the first 3 months of life in 90 and 94% of infants with toxoplasmosis, respectively, with a specificity of 99.8% and a positive predictive value of 99% at 8 months of age. This dual diagnostic approach (ELIFA and IgM-IgA immunocapture) is highly efficient and has important implications for therapy. Indeed, early postnatal diagnosis based on objective evidence enables therapy with pyrimethamine-sulfadoxine to be started immediately for 24 months, while spiramycin (which used to be given preventively for 9 to 12 months to all infants at risk) can be stopped after the first 3 months of life.
Services de Parasitologie, Centre Hospitalier Universitaire, Reims, France.
J M
JM
Pinon
C
C
Chemla
I
I
Villena
F
F
Foudrinier
D
D
Aubert
D
D
Puygauthier-Toubas
B
B
Leroux
D
D
Dupouy
C
C
Quereux
M
M
Talmud
T
T
Trenque
G
G
Potron
M
M
Pluot
G
G
Remy
A
A
Bonhomme
D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007124:Immunoenzyme Techniques; D007070:Immunoglobulin A / Q000097:blood*; D007075:Immunoglobulin M / Q000097:blood*; D007223:Infant; D007231:Infant, Newborn; D014122:Toxoplasma / Q000276:immunology*; D014125:Toxoplasmosis, Congenital / Q000175:diagnosis* / Q000188:drug therapy
D000913:Antibodies, Protozoan; D007070:Immunoglobulin A; D007075:Immunoglobulin M