El-Bali Mohammed, Zaglool Dina A M, Khodari Yousif A W, Al-Harthi Saeed A
J Egypt Soc Parasitol. 2016 Apr;46(1):201-8. doi: 10.12816/0026165.
Congenital toxoplasmosis is associated with important morbidity and mortality. Since vertical transmission of Toxoplasma gondii can occur in acute cases, antenatal screening for recent infections is vital. Accurate determination of acute toxoplasmosis requires a combination of immunoassays, usually not routinely applied for screening purposes. This study evaluated the anti-T. gondii (IgG+IgM)/IgM prenatal screening procedure by IgG avidity assay. The routine prenatal screening for (IgG+IgM) anti-T. gondii by indirect hemagglutination (IHA) in serum samples was done of 2247 pregnant women who attended two hospitals between 2011 and 2013 revealed 487 (21.7%) positive samples. Examination of IHA-positive sera by IgM and IgG/IgG-avidity concurrent ELISA tests revealed 7 positive and 3 border-line IgM-ELISA titers during the initial check-up of 10 women, who were then followed up at 3-4 week-intervals. Among these, 4 (40%) showed simultaneous high avidity IgG antibodies, indicating distant infection by the parasite, and no anti-T. gondii specific IgG could be detected in follow-up sera of two cases (20%), indicating false IgM initial positive results. Only 4 (40%) women showed simultaneous IgM and low avidity IgG antibodies indicating active infections. Avoidance of an over-diagnosis of acute toxoplasmosis Anti-T. gondii (IgG+IgM)/IgM prenatal screening must be supplemented by a discriminative test like IgG avidity ELISA.
先天性弓形虫病与严重的发病和死亡相关。由于急性弓形虫病病例中可发生弓形虫垂直传播，因此对近期感染进行产前筛查至关重要。准确诊断急性弓形虫病需要联合使用免疫测定法，而这些方法通常并非用于常规筛查目的。本研究通过IgG亲和力测定评估了抗弓形虫（IgG+IgM）/IgM产前筛查程序。采用间接血凝试验（IHA）对2011年至2013年间在两家医院就诊的2247名孕妇血清样本进行常规产前抗弓形虫（IgG+IgM）筛查，结果显示487份（21.7%）样本呈阳性。通过IgM和IgG/IgG亲和力同步ELISA检测对IHA阳性血清进行检测，在对10名女性的初次检查中发现7份IgM-ELISA滴度呈阳性和3份临界阳性，随后每3至4周进行一次随访。其中，4名（40%）女性同时显示高亲和力IgG抗体，表明为寄生虫的远期感染，2例（20%）女性的随访血清中未检测到抗弓形虫特异性IgG，表明IgM初始阳性结果为假阳性。只有4名（40%）女性同时显示IgM和低亲和力IgG抗体，表明为活动性感染。避免急性弓形虫病的过度诊断 抗弓形虫（IgG+IgM）/IgM产前筛查必须辅以如IgG亲和力ELISA等鉴别试验。
