Background: Chronic Chagas disease (CChD), one of the infectious parasitic diseases with the greatest social and economic impact upon a large part of the American continent, has distinct clinical manifestations in humans (cardiac, digestive, or mixed clinical forms). The mechanisms underlying the development of the most common and ominous clinical form, the chronic Chagas cardiomyopathy (CCC) have not been completely elucidated, despite the fact that a high intensity of parasite persistence in the myocardium is deemed responsible for an untoward evolution of the disease. The present study aimed to assess the parasite load CCC and its relation to left ventricular ejection fraction (LVEF), a definite prognostic marker in patients with CCC.

Methods: Patients with CCC were clinically evaluated using 12-lead-electrocardiogram, echocardiogram, chest X-ray. Peripheral blood sampling (5 ml of venous blood in guanidine/EDTA) was collected from each patient for subsequent DNA extraction and the quantification of the parasite load using real-time PCR.

Results: One-hundred and eighty-one patients with CCC were evaluated. A total of 140 (77.3%) had preserved left ventricular ejection fraction (of ≥40%), and 41 individuals had LV dysfunction (LVEF of <40%). A wide variation in parasite load was observed with a, mean of 1.3460 ± 2.0593 (0.01 to 12.3830) par. Eq./mL. The mean ± SD of the parasite load was 0.6768 ± 0.9874 par. Eq./mL and 3.6312 ± 2.9414 par. Eq./mL in the patients with LVEF ≥ 40% and <40%, respectively.

Conclusion: The blood parasite load is highly variable and seems to be directly related to the reduction of LVEF, an important prognostic factor in CCC patients.

背景：慢性恰加斯病 (CChD) 是对美洲大陆大部分地区社会和经济影响最大的传染性寄生虫病之一，在人类中具有明显的临床表现（心脏、消化系统或混合临床形式）。最常见和不祥的临床形式慢性恰加斯心肌病 (CCC) 发展的潜在机制尚未完全阐明，尽管心肌中高强度的寄生虫持续存在被认为是该疾病不利演变的原因. 本研究旨在评估寄生虫负荷 CCC 及其与左心室射血分数 (LVEF) 的关系，LVEF 是 CCC 患者的明确预后标志物。

方法：使用 12 导联心电图、超声心动图、胸部 X 线对 CCC 患者进行临床评估。从每位患者身上采集外周血样本（5 ml 胍/EDTA 中的静脉血），用于随后的 DNA 提取和使用实时 PCR 对寄生虫载量进行量化。

结果：评估了 181 名 CCC 患者。共有 140 人 (77.3%) 的左心室射血分数保持不变（≥40%），41 人有左心室功能障碍（LVEF <40%）。观察到寄生虫负载的广泛变化，平均值为 1.3460 ± 2.0593（0.01 至 12.3830）。当量/毫升。寄生虫负荷的平均值 ± SD 为 0.6768 ± 0.9874 par。Eq./mL 和 3.6312 ± 2.9414 par. Eq./mL 分别在 LVEF ≥ 40% 和 <40% 的患者中。

结论： 血液寄生虫负荷变化很大，似乎与 LVEF 的降低直接相关，LVEF 是 CCC 患者的重要预后因素。