enose analysis of volatile chemicals from dogs naturally infected with leishmania infantum in brazil
monica e. staniek ,luigi sedda ,tim d. gibson, cristian f. de souza,erika m. costa, rod j. dillon,james g. c. hamilton
abstractbackgroundvisceral leishmaniasis (vl) in brazil is a neglected, vector-borne, tropical parasitic disease that is responsible for several thousａnd human deaths every year. the transmission route involves sａnd flies becoming infected after feeding on infected reservoir host, mainly dogs, and then transmitting the leishmania infantum parasites while feeding on humans. a major component of the vl control effort is the identification and euthanasia of infected dogs to remove them as a source of infection. a rapid, non-invasive, point-of-care device able to differentiate between the odours of infected and uninfected dogs may contribute towards the accurate diagnosis of canine vl.
methodology/principal findingswe analysed the headspace volatile chemicals from the hair of two groups of dogs collected in 2017 and 2018 using a bench-top enose volatile organic chemical analyser. the dogs were categorised as infected or uninfected by pcr analysis of blood samples taken by venepuncture and the number of parasites per ml of blood was calculated for each dog by qpcr analysis. we demonstrated using a robust clustering analysis that the enose data could be discriminated into infected and uninfected categories with specificity >94% and sensitivity >97%. the enose device and data analysis were sufficiently sensitive to be able to identify infected dogs even when the leishmania population in the circulating blood was very low.
conclusions/significancethe study illustrates the potential of the enose to rapidly and accurately identify dogs infected with le. infantum. future improvements to enose analyser sensor sensitivity, sampling methodology and portability suggest that this approach could significantly improve the diagnosis of vl infected dogs in brazil with additional potential for effective diagnosis of vl in humans as well as for the diagnosis of other parasitic diseases.
背景
巴西杜氏利什曼原虫（vl）是一种被忽视的、媒介传播的热带寄生虫病，每年造成数千人死亡。传播途径包括沙蝇以感染宿主（主要是狗）为食后感染，再以人为食传播利什曼原虫。vl控制工作的一个主要组成部分是对被感染的狗进行鉴定和，以消除它们作为感染源的作用。一种能够区分感染犬和未感染犬气味的快速、、定点护理设备可能有助于犬vl的准确诊断。
方法/主要发现
我们使用台式enose挥发性有机化学分析仪分析了2017年和2018年收集的两组狗的毛发中的顶空挥发性化学物质。通过对静脉穿刺采集的血液样本进行pcr分析，将狗分为感染型和未感染型，并通过qpcr分析计算每只狗每毫升血液中的寄生虫数量。我们用稳健的聚类分析证明，enose数据可分为感染和未感染两类，特异性>94%，敏感性>97%。enose装置和数据分析非常敏感，即使在循环血液中利什曼原虫的数量非常少的情况下，也能够识别受感染的狗。
结论/意义
研究表明，enose对快速、准确地鉴别初期感染le的犬具有潜在的作用。enose分析仪传感器灵敏度、取样方法和便携性的未来改进表明，这种方法可以显著提高巴西vl感染犬的诊断水平，对人类vl的有效诊断以及其他寄生虫病的诊断具有额外的潜力。