Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru.
PLoS Negl Trop Dis. 2010 Feb 23;4(2):e612. doi: 10.1371/journal.pntd.0000612.
Renal carriage and shedding of leptospires is characteristic of carrier or maintenance animal hosts. Sporadic reports indicate that after infection, humans may excrete leptospires for extended periods. We hypothesized that, like mammalian reservoir hosts, humans develop asymptomatic leptospiruria in settings of high disease transmission such as the Peruvian Amazon.
METHODOLOGY/PRINCIPAL FINDINGS: Using a cross-sectional study design, we used a combination of epidemiological data, serology and molecular detection of the leptospiral 16S rRNA gene to identify asymptomatic urinary shedders of Leptospira. Approximately one-third of the 314 asymptomatic participants had circulating anti-leptospiral antibodies. Among enrolled participants, 189/314 (59%) had evidence of recent infection (microscopic agglutination test (MAT0 >or=1:800 or ELISA IgM-positive or both). The proportion of MAT-positive and high MAT-titer (>or=1:800) persons was higher in men than women (p = 0.006). Among these people, 13/314 (4.1%) had Leptospira DNA-positive urine samples. Of these, the 16S rRNA gene from 10 samples was able to be sequenced. The urine-derived species clustered within both pathogenic (n = 6) and intermediate clades of Leptospira (n = 4). All of the thirteen participants with leptospiral DNA in urine were women. The median age of the DNA-positive group was older compared to the negative group (p<or=0.05). A group of asymptomatic participants ("long-term asymptomatic individuals," 102/341 (32.5%) of enrolled individuals) without serological evidence of recent infection was identified; within this group, 6/102 (5.9%) excreted pathogenic and intermediate-pathogenic Leptospira (75-229 bacteria/mL of urine).
CONCLUSIONS/SIGNIFICANCE: Asymptomatic renal colonization of leptospires in a region of high disease transmission is common, including among people without serological or clinical evidence of recent infection. Both pathogenic and intermediate Leptospira can persist as renal colonization in humans. The pathogenic significance of this finding remains to be explored but is of fundamental biological significance.
肾脏携带和排出钩端螺旋体是带菌者或维持宿主的特征。零星报告表明，感染后，人类可能会在很长一段时间内排出钩端螺旋体。我们假设，与哺乳动物储存宿主一样，人类在疾病传播率高的环境中（如秘鲁亚马逊地区）会出现无症状的尿钩端螺旋体。
方法/主要发现：我们采用横断面研究设计，结合流行病学数据、血清学和钩端螺旋体 16S rRNA 基因的分子检测，来确定无症状的尿钩端螺旋体携带者。在 314 名无症状参与者中，约有三分之一的人有循环抗钩端螺旋体抗体。在入组的参与者中，189/314（59%）有近期感染的证据（显微镜凝集试验（MAT0≥1:800 或 ELISA IgM 阳性或两者均阳性）。男性的 MAT 阳性和高 MAT 滴度（≥1:800）者比例高于女性（p=0.006）。在这些人中，314 名中有 13/314（4.1%）的尿液样本中有钩端螺旋体 DNA 阳性。其中，10 份尿液样本的 16S rRNA 基因能够被测序。从尿液中分离出的物种聚集在致病性（n=6）和中间群的钩端螺旋体（n=4）中。所有 13 名尿液中含有钩端螺旋体 DNA 的参与者均为女性。DNA 阳性组的中位年龄高于阴性组（p<0.05）。我们确定了一组无症状参与者（“长期无症状个体”，入组的 341 名参与者中有 102/341（32.5%）），他们没有近期感染的血清学证据；在这个组中，有 6/102（5.9%）排泄致病性和中间致病性钩端螺旋体（尿液中 75-229 个细菌/mL）。
结论/意义：在疾病传播率高的地区，无症状的肾脏钩端螺旋体定植很常见，包括没有近期感染的血清学或临床证据的人。致病性和中间致病性的钩端螺旋体都可以作为肾脏定植在人体内持续存在。这一发现的致病性意义仍有待探索，但具有重要的生物学意义。
