Department of Clinical and Biological Sciences, University of Torino, Infectious Diseases Unit, Corso Dante 202, 10141 Asti, Italy.
J Clin Microbiol. 2010 Jan;48(1):131-6. doi: 10.1128/JCM.00416-09. Epub 2009 Nov 18.
The prevalence of Leishmania infantum-specific antibodies and asymptomatic infection was assessed in a randomized sample of 526 healthy adults from a continental area of northwestern Italy where L. infantum is not endemic and where autochthonous cases of visceral leishmaniasis (VL) were recently reported. L. infantum-specific antibodies were detected by Western blotting (WB) in 39 subjects (7.41%), while L. infantum kinetoplast DNA was amplified from buffy coat in 21 out of 39 WB-positive subjects, confirming asymptomatic infection in 53.8% of seropositives. Risk factors significantly associated with WB positivity were uninterrupted residence since childhood in a local rural environment (odds ratio [OR], 3.5; 95% confidence interval [CI], 1.7 to 7.3), daily contact with animals though not exclusively with dogs (OR, 3.7; 95% CI, 1.3 to 10.7), older age (OR, 2.31; 95% CI, 1.2 to 4.5), and agricultural/other outdoor activities (OR, 3.8; 95% CI, 0.99 to 3.7.) Logistic regression analysis showed that uninterrupted residence in a local rural environment and an age of >65 years were the only independent predictors of seropositivity assessed by WB. Follow-up at 24 months did not show evidence of VL in either seropositive or PCR-positive subjects. The detection of a high seroprevalence rate, confirmed as asymptomatic infection by PCR in more than half of the cases, among healthy residents in a continental area of northwestern Italy makes local L. infantum transmission very likely. In a region where VL is considered nonendemic, these findings warrant further epidemiological investigations as well as interventions with respect to both the canine reservoir and vectors, given the possible risks for immunosuppressed patients.
在意大利西北部一个大陆地区，对 526 名健康成年人进行了随机抽样，评估利什曼原虫特异性抗体和无症状感染的流行情况。该地区并非利什曼原虫流行地区，也没有本土内脏利什曼病（VL）病例报告。通过 Western blot（WB）检测到 39 名受试者（7.41%）存在利什曼原虫特异性抗体，而在 39 名 WB 阳性受试者中，有 21 名从白细胞中扩增出利什曼原虫动基体 DNA，证实 53.8%的血清阳性者存在无症状感染。与 WB 阳性显著相关的危险因素是自童年以来一直在当地农村环境中不间断居住（比值比[OR]，3.5；95%置信区间[CI]，1.7 至 7.3）、每天与动物接触（不限于狗）（OR，3.7；95%CI，1.3 至 10.7）、年龄较大（OR，2.31；95%CI，1.2 至 4.5）和从事农业/其他户外活动（OR，3.8；95%CI，0.99 至 3.7）。Logistic 回归分析显示，在当地农村环境中不间断居住和年龄 >65 岁是 WB 评估的血清阳性的唯一独立预测因素。24 个月的随访未发现血清阳性或 PCR 阳性受试者出现 VL 的证据。在意大利西北部一个大陆地区，健康居民中存在高血清流行率，其中超过一半的病例通过 PCR 证实为无症状感染，这表明当地存在利什曼原虫传播。在一个被认为是非流行地区的地区，这些发现需要进一步进行流行病学调查，以及针对犬类储存宿主和媒介进行干预，因为这可能对免疫抑制患者构成风险。
