Instituto de Zoonosis Luis Pasteur, Av. Díaz Vélez 4821, Ciudad Autónoma de Buenos Aires, Argentina.
Instituto de Zoonosis Luis Pasteur, Av. Díaz Vélez 4821, Ciudad Autónoma de Buenos Aires, Argentina.
Ticks Tick Borne Dis. 2019 Oct;10(6):101282. doi: 10.1016/j.ttbdis.2019.101282. Epub 2019 Aug 26.
This study was aimed to know epidemiological aspects of Borrelia spp. in a protected urban area of Buenos Aires city, Argentina, where thousands of people visit this area for recreational purposes. Ticks were collected from vegetation, birds and dogs. Three hundred and forty birds belonging to 43 species, 41 genera, 18 families and six orders were captured (90.3% corresponded to the order Passeriformes). One hundred and twenty ticks were collected from 47 birds (13.8%) belonging to 10 species (23.2%), all of them from to the order Passeriformes (Emberizidae, Furnariidae, Parulidae, Thraupidae, Troglodytidae, Turdidae). Ticks were identified as Ixodes auritulus (56 larvae, 44 nymphs and 8 females) and Amblyomma aureolatum (1 larva and 11 nymphs). One thousand and ninety-one ticks collected from vegetation, 100 ticks collected from birds, and 89 ticks from dogs were tested for Borrelia infection by PCR trials targeting the flagellin (fla) and 16S rRNA genes. In addition, 101 blood and 168 tissue samples from birds were analyzed. Nine nymphs of A. aureolatum (2.1%) and four nymphs of I. auritulus (0.7%) collected from vegetation were positive. Five nymphs of A. aureolatum (45.4%), and five pools of larvae (minimum infection rate 13.5%), 18 nymphs (40.9%) and one female (14.3%) of I. auritulus collected on birds were also positive. The remaining samples were negative. The phylogenetic tree generated with fla sequences shows that seven of the eight different haplotypes of Borrelia detected in I. auritulus conform an independent lineage within the Borrelia burgdorferi sensu lato complex together with sequences of Borrelia sp. detected in I. auritulus from Canada and Uruguay. The fla sequences of Borrelia obtained from A. aureolatum and one sequence of a single specimen of I. auritulus conform a phylogenetic group with Borrelia turcica, Borrelia sp. isolated from a tortoise in Zambia, Borrelia spp. detected in Amblyomma maculatum from USA and Amblyomma longirostre from Brazil. The epidemiological risk that implies the infection with Borrelia genospecies associated with I. auritulus seems to be low because this tick is not aggressive to humans, but it helps to maintain borrelial spirochetes in the enzootic transmission cycles. The pathogenicity to humans of the Borrelia found in A. aureolatum is unknown; however, adults of this tick species are known to bite humans. This is the first report of the presence of Borrelia in A. aureolatum. Further investigations are necessary to know the risk of transmission of borreliosis by hard ticks in the study area.
本研究旨在了解阿根廷布宜诺斯艾利斯市一个受保护城区中伯氏疏螺旋体的流行病学特征，因为有成千上万的人前往该地区进行娱乐活动。从植被、鸟类和狗身上采集了蜱虫。共捕获了 340 只属于 43 种、41 属、18 科和 6 目的鸟类（90.3%属于雀形目）。从 10 种（占 23.2%）鸟类中采集了 120 只蜱虫（13.8%），全部来自雀形目（织雀科、灶鸟科、霸鹟科、唐纳雀科、画眉科、鸫科）。鉴定出的蜱虫为肩突硬蜱（56 只幼虫、44 只若虫和 8 只雌虫）和美洲钝眼蜱（1 只幼虫和 11 只若虫）。从植被中采集了 1091 只蜱虫，从鸟类中采集了 100 只蜱虫，从狗中采集了 89 只蜱虫，通过针对鞭毛（fla）和 16S rRNA 基因的 PCR 试验检测这些蜱虫的伯氏疏螺旋体感染情况。此外，还分析了 101 份鸟类血液和 168 份鸟类组织样本。从植被中采集的 9 只美洲钝眼蜱（2.1%）和 4 只肩突硬蜱（0.7%）呈阳性。从鸟类上采集的 5 只美洲钝眼蜱（45.4%）和 5 只幼虫（最低感染率为 13.5%）、18 只若虫（40.9%）和 1 只雌虫（14.3%）的肩突硬蜱也呈阳性。其余样本均为阴性。fla 序列生成的系统发育树显示，在肩突硬蜱中检测到的 8 种不同单倍型中的 7 种伯氏疏螺旋体与在加拿大和乌拉圭从肩突硬蜱中检测到的伯氏疏螺旋体构成了一个独立的谱系。从美洲钝眼蜱中获得的 fla 序列和一只肩突硬蜱的单一样本序列与土耳其伯氏疏螺旋体、从赞比亚一只乌龟中分离出的伯氏疏螺旋体、从美国采集的美洲钝眼蜱和从巴西采集的美洲钝眼蜱中分离出的伯氏疏螺旋体形成一个系统发育群。与肩突硬蜱相关的伯氏疏螺旋体感染的流行病学风险似乎较低，因为这种蜱虫对人类不具有攻击性，但它有助于维持地方性传播循环中的伯氏疏螺旋体。目前尚不清楚从美洲钝眼蜱中发现的伯氏疏螺旋体对人类的致病性；然而，这种蜱虫的成虫已知会叮咬人类。这是首次报道美洲钝眼蜱中存在伯氏疏螺旋体。需要进一步调查，以了解研究区域中硬蜱传播莱姆病的风险。
