Congenital toxoplasmosis: evaluation of molecular and serological methods for achieving economic and early diagnosis among Egyptian preterm infants.
BACKGROUND
Early diagnosis of congenital toxoplasmosis (CT) is difficult when specific immunoglobulin M (IgM) antibodies are absent, or if persist for months, in the newborn infant's blood.


OBJECTIVE
To study the risk factors of neonatal toxoplasmosis and to compare different immunologic profiles (Toxoplasma-specific IgM, IgA antibodies and the avidity of IgG antibodies) with polymerase chain reaction (PCR) for reaching economic and early postnatal diagnosis.


METHODS
We prospectively studied 80 preterm neonates, recruited from neonatal intensive care units (NICUs) of Cairo University hospitals. Whose gestational age ≤ 34 weeks with (n = 60) or without (n = 20) CT risk. Serum samples for specific IgA, IgM antibodies and avidity of IgG toxoplasma antibodies were measured by ELISA then compared to PCR.


RESULTS
Of the 60 studied cases, 16 (26.7%) were positive for toxoplasmosis by PCR, of which 15 (25%) had low avidity of IgG antibodies (positive), 14 (23.3%) were positive for IgA and 10 (16.7%) were positive for IgM, with sensitivity for avidity of IgG, IgA and IgM: 93.2%, 87.5% and 62.5%, respectively.


CONCLUSIONS
Determination of avidity of IgG toxoplasma antibodies and/or serological detection of specific IgA for toxoplasmosis offer, simple tests for diagnosis of congenital toxoplasmosis with (better sensitivity) than IgM.
Department of Neonatology, Cairo University Children's Hospital, Cairo, Egypt. reemnbl@yahoo.com
Reem N
RN
Said
Mayssa M
MM
Zaki
Manal B
MB
Abdelrazik
D000913:Antibodies, Protozoan / Q000097:blood*; D000915:Antibody Affinity; D042241:Early Diagnosis; D004534:Egypt; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D007231:Infant, Newborn; D007234:Infant, Premature; D007235:Infant, Premature, Diseases / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D008297:Male; D015997:Neonatal Screening / Q000191:economics / Q000379:methods*; D016133:Polymerase Chain Reaction; D011446:Prospective Studies; D012307:Risk Factors; D012680:Sensitivity and Specificity; D014122:Toxoplasma / Q000276:immunology*; D014125:Toxoplasmosis, Congenital / Q000097:blood / Q000175:diagnosis* / Q000276:immunology
D000913:Antibodies, Protozoan; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M