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
Abstract
Background
Visceral 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 findings
We 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/Significance
The study illustrates the potential of the eNose to rapidly and accuray 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
巴西杜氏利什曼原蟲(chóng)(VL)是一種被忽視的、媒介傳播的熱帶寄生蟲(chóng)病，每年造成數(shù)千人死亡。傳播途徑包括沙蠅以感染宿主(主要是狗)為食后感染，再以人為食傳播利什曼原蟲(chóng)。VL控制工作的一個(gè)主要組成部分是對(duì)被感染的狗進(jìn)行鑒定和，以消除它們作為感染源的作用。一種能夠區(qū)分感染犬和未感染犬氣味的快速、無(wú)創(chuàng)、定點(diǎn)護(hù)理設(shè)備可能有助于犬VL的準(zhǔn)確診斷。
方法/主要發(fā)現(xiàn)
我們使用臺(tái)式eNose揮發(fā)性有機(jī)化學(xué)分析儀分析了2017年和2018年收集的兩組狗的毛發(fā)中的頂空揮發(fā)性化學(xué)物質(zhì)。通過(guò)對(duì)靜脈穿刺采集的血液樣本進(jìn)行PCR分析，將狗分為感染型和未感染型，并通過(guò)qPCR分析計(jì)算每只狗每毫升血液中的寄生蟲(chóng)數(shù)量。我們用穩(wěn)健的聚類(lèi)分析證明，enose數(shù)據(jù)可分為感染和未感染兩類(lèi)，特異性>94%，敏感性>97%。enose裝置和數(shù)據(jù)分析非常敏感，即使在循環(huán)血液中利什曼原蟲(chóng)的數(shù)量非常少的情況下，也能夠識(shí)別受感染的狗。
結(jié)論/意義
研究表明，enose對(duì)快速、準(zhǔn)確地鑒別初期感染Le的犬具有潛在的作用。enose分析儀傳感器靈敏度、取樣方法和便攜性的未來(lái)改進(jìn)表明，這種方法可以顯著提高巴西VL感染犬的診斷水平，對(duì)人類(lèi)VL的有效診斷以及其他寄生蟲(chóng)病的診斷具有額外的潛力。
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