Schijman Alejandro G, Altcheh Jaime, Burgos Juan M, Biancardi Miguel, Bisio Margarita, Levin Mariano J, Freilij Héctor
Laboratorio de Biología Molecular de la Enfermedad de Chagas, Instituto de Ingeniería Genética y Biología Molecular (INGEBI), Buenos Aires, Argentina.
J Antimicrob Chemother. 2003 Sep;52(3):441-9. doi: 10.1093/jac/dkg338. Epub 2003 Aug 13.
This prospective study focused on the evaluation of anti-parasitic therapy in congenital Chagas' disease, diagnosed and monitored by PCR and conventional diagnosis.
We studied 152 children born to seroreactive mothers, living in a non-endemic area. Fifty infants aged 0-6 months (GA) were diagnosed by microhaematocrit and PCR and 102 children aged 7 months to 17 years (GB) were diagnosed by serology and PCR. Forty treated patients were monitored for 2 or 3 years by PCR and conventional methods. A competitive-quantitative PCR was used to determine pre-therapy parasitic loads and follow their post-treatment evolution.
In GA, the sensitivities of the PCR and microhaematocrit were 100% and 82.4% and their specificities 97% and 100%, respectively. In GB, the sensitivity of the PCR was 73.8% with a specificity of 100%. Pre-therapy parasitic loads ranged from 12.5 to 125,000 and 12.5 to 125 parasite genomic equivalents/mL of blood in GA and GB, respectively. PCR turned negative in all treated pre-therapy PCR positive patients before or at the end of treatment, which was followed by their seronegativation in 10/10 GA, in 3/5 children initiating therapy at 7 months to 2 years of age but in 0/16 initiating therapy at an older age. Two out of the latter patients were occasionally PCR positive during post-treatment, suggesting no parasitological response. Out of nine pre-therapy PCR negative patients, four turned seronegative after treatment, suggesting that in undetermined patients, undetectable parasitic burdens may lead to better post-treatment prognosis.
PCR was useful for sensitive diagnosis and therapy monitoring, allowing early detection of refractory cases.
本前瞻性研究聚焦于通过聚合酶链反应（PCR）和传统诊断方法对先天性恰加斯病进行诊断和监测，并评估抗寄生虫治疗效果。
我们研究了152名血清反应阳性母亲所生的儿童，他们生活在非流行地区。50名年龄在0至6个月（GA组）的婴儿通过微量血细胞比容法和PCR进行诊断，102名年龄在7个月至17岁（GB组）的儿童通过血清学和PCR进行诊断。40名接受治疗的患者通过PCR和传统方法进行了2至3年的监测。采用竞争性定量PCR来确定治疗前的寄生虫负荷，并跟踪其治疗后的变化。
在GA组中，PCR和微量血细胞比容法的敏感性分别为100%和82.4%，特异性分别为97%和100%。在GB组中，PCR的敏感性为73.8%，特异性为100%。治疗前GA组和GB组的寄生虫负荷分别为每毫升血液12.5至125,000个和12.5至125个寄生虫基因组当量。所有治疗前PCR阳性的患者在治疗前或治疗结束时PCR转为阴性，随后在10/10的GA组、3/5在7个月至2岁开始治疗的儿童中血清转为阴性，但在16名年龄较大开始治疗的儿童中血清未转阴。后一组患者中有2名在治疗后偶尔PCR呈阳性，提示无寄生虫学反应。在9名治疗前PCR阴性的患者中，4名在治疗后血清转阴，这表明在未明确诊断的患者中，无法检测到的寄生虫负荷可能导致更好的治疗后预后。
PCR有助于敏感诊断和治疗监测，能够早期发现难治性病例。
