Laboratoire de Parasitologie-Mycologie, Université Joseph Fourier, Grenoble 1 et Centre Hospitalier Universitaire A. Michallon, Grenoble, France.
J Clin Microbiol. 2013 Jul;51(7):2103-11. doi: 10.1128/JCM.00169-13. Epub 2013 Apr 24.
Classically, Toxoplasma infection is associated with high levels of specific IgM antibody and a rise in specific IgG levels 1 to 3 weeks later. Atypical IgG seroconversion, without IgM detection or with transient IgM levels, has been described during serologic follow-up of seronegative pregnant women and raises difficulties in interpreting the results. To evaluate the frequency and the characteristics of these atypical cases of seroconversion, an investigation was conducted within the French National Reference Center for Toxoplasmosis, from which 26 cases collected from 12 laboratories belonging to the network were identified. The aim of this work was to retrospectively analyze the results of serologic testing, the treatments administered, and the results of prenatal and postnatal follow-up for these women. In each case, IgG antibodies were detected using both screening and confirmatory tests. IgM antibodies were not detected in 15 cases, and the levels were equivocal or low-positive in 11 cases. The IgG avidity results were low in 16 cases and high in one case. Most of the pregnant women (22/26) were treated with spiramycin from the time that IgG antibodies appeared until delivery. Amniotic fluid was analyzed for Toxoplasma gondii DNA by PCR in 11/26 cases, and the results were negative in all cases. Congenital toxoplasmosis was ruled out in 12/26 newborns. There was no abnormality observed at birth for 10 newborns and no information available for 4 newborns. In conclusion, when the interpretation of serological results is so difficult, it seems cautious to initiate treatment by spiramycin and to follow the pregnant women and their newborns.
经典情况下，弓形虫感染与高水平的特异性 IgM 抗体相关，并在 1 至 3 周后特异性 IgG 水平升高。在对血清阴性孕妇进行血清学随访期间，已描述了不检测 IgM 或 IgM 水平短暂出现的非典型 IgG 血清转换，这给结果解释带来了困难。为了评估这些非典型血清转换病例的频率和特征，在法国国家弓形虫病参考中心进行了一项调查，从属于该网络的 12 个实验室中收集到了 26 例。本研究的目的是回顾性分析这些妇女的血清学检测结果、所给予的治疗以及产前和产后随访的结果。在每种情况下，均使用筛选和确认试验检测 IgG 抗体。在 15 例中未检测到 IgM 抗体，在 11 例中 IgM 抗体水平为不确定或低阳性。16 例 IgG 亲和力结果较低，1 例结果较高。大多数孕妇（22/26）在 IgG 抗体出现至分娩期间用螺旋霉素治疗。在 11/26 例中通过 PCR 分析羊水的弓形虫 DNA，所有结果均为阴性。12/26 名新生儿排除了先天性弓形虫病。10 名新生儿出生时无异常，4 名新生儿无信息。总之，当血清学结果的解释如此困难时，似乎谨慎的做法是开始用螺旋霉素治疗，并对孕妇及其新生儿进行随访。
