Blanco S B, Segura E L, Gürtler R E
Servicio Nacional de Chagas, Córdoba, Argentina.
Medicina (B Aires). 1999;59 Suppl 2:138-42.
The vertical transmission of Trypanosoma cruzi has been augmenting its relative importance as vector and transfusion-mediated transmission routes have been, and continue to be, increasingly controlled. The vertical transmission of T. cruzi cannot be prevented; but early detection and treatment of congenital infection achieve cure rates close to 100%. In Argentina, the Subprogram of Control of Pregnant Women examined 58,196 women from 13 provinces in 1997 and found a 9% seropositivity to T. cruzi. In spite of such high maternal prevalence rates of T. cruzi, only a small proportion of live newborns to infected mothers acquires the infection. The probability of vertical transmission was 1.9% (range: 0.1% to 3.5%) in surveys carried out in the '70s, and 2.5% (range: 0.7% to 10.4%) in others conducted in the '70-'80s. Other more recent studies in Argentina estimated the probability of transmission in 2.6%-6.7%, but studies from Paraguay estimated 10.5% by PCR or serodiagnosis. The microhematocrit technique is the recommended parasitologic method to detect congenital infection. Routine serodiagnosis that detects IgG against T. cruzi is only helpful after the newborn reaches 6 months of age. Detection of specific IgM using recombinant antigens and PCR constitute excellent alternatives, but their feasibility from operational and cost-effective viewpoints in affected endemic areas remains to be considered. In a longitudinal project carried out in Maternidad Nuestra Señora de la Merced in the city of Tucumán between 1992-1994, the majority of congenital cases were asymptomatic. They were diagnosed through the microhematocrit technique, but a number of cases could only be detected later as a result of the parasitological and/or serological follow-up. Of a total of 32 newborns infected with T. cruzi who were treated with nifurtimox or benznidazole, 30 had a negative microhematocrit and serodiagnosis between 6 months and 2 years post-treatment. The magnitude of congenital transmission, and its associated morbidity and mortalidad, largely justify the efforts needed to detect T. cruzi infection in the mothers and newborns. This project demonstrated that the transmission of T. cruzi can be successfully controlled at a provincial scale through a specific program inserted in the primary health care system or at the first level of attention. The congenital transmission of T. cruzi clearly represents a public health problem in areas that in the past were of active transmission, even years after being under entomologic surveillance.
随着媒介传播和输血介导传播途径一直以来并将持续得到越来越有效的控制，克氏锥虫的垂直传播的相对重要性日益增加。克氏锥虫的垂直传播无法预防；但先天性感染的早期检测和治疗可实现接近100%的治愈率。在阿根廷，1997年孕妇控制子项目对来自13个省份的58196名妇女进行了检查，发现克氏锥虫血清阳性率为9%。尽管克氏锥虫在母亲中的流行率如此之高，但感染母亲所生的活产新生儿中只有一小部分会感染。在70年代进行的调查中，垂直传播的概率为1.9%（范围：0.1%至3.5%），在70至80年代进行的其他调查中为2.5%（范围：0.7%至10.4%）。阿根廷其他近期研究估计传播概率为2.6%-6.7%，但巴拉圭的研究通过PCR或血清学诊断估计为10.5%。微量血细胞比容技术是检测先天性感染推荐的寄生虫学方法。检测抗克氏锥虫IgG的常规血清学诊断仅在新生儿满6个月后才有用。使用重组抗原检测特异性IgM和PCR是很好的替代方法，但从受影响流行地区的操作和成本效益角度来看，其可行性仍有待考虑。在1992 - 1994年期间于图库曼市的我们的圣母马利亚妇产医院开展的一项纵向项目中，大多数先天性病例无症状。它们通过微量血细胞比容技术诊断，但一些病例只能在寄生虫学和/或血清学随访后才能检测到。在总共32名接受硝呋莫司或苯硝唑治疗的感染克氏锥虫的新生儿中，30名在治疗后6个月至2年的微量血细胞比容和血清学诊断呈阴性。先天性传播的程度及其相关的发病率和死亡率，在很大程度上证明了检测母亲和新生儿中克氏锥虫感染所需努力的合理性。该项目表明，通过纳入初级卫生保健系统或一级护理的特定项目，可以在省级层面成功控制克氏锥虫的传播。在过去存在活跃传播的地区，即使在昆虫学监测多年之后，克氏锥虫的先天性传播显然仍是一个公共卫生问题。
