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. 2023 Sep 19:10:1185779.
doi: 10.3389/fmed.2023.1185779. eCollection 2023.

Sniffing out safety: canine detection and identification of SARS-CoV-2 infection from armpit sweat

Chris Callewaert  1 , Maria Pezavant  2 , Rony Vandaele  3 , Bart Meeus  3 , Ellen Vankrunkelsven  3 , Phaedra Van Goethem  3 , Alain Plumacker  4 , Benoit Misset  5 , Gilles Darcis  6 , Sonia Piret  7 , Lander De Vleeschouwer  8 , Frank Staelens  9 , Kristel Van Varenbergh  9 , Sofie Tombeur  9 , Anouck Ottevaere  10 , Ilke Montag  11 , Patricia Vandecandelaere  12 , Stijn Jonckheere  12 , Linos Vandekerckhove  13 , Els Tobback  14 , Gregoire Wieers  15   16 , Jean-Christophe Marot  15 , Kurt Anseeuw  17 , Leen D'Hoore  18   17 , Sebastiaan Tuyls  19 , Brecht De Tavernier  20 , Julie Catteeuw  21 , Ali Lotfi  22 , Alexey Melnik  22 , Alexander Aksenov  22 , Dominique Grandjean  23 , Miguel Stevens  24 , Frank Gasthuys  25 , Hugues Guyot  2
Affiliations

Sniffing out safety: canine detection and identification of SARS-CoV-2 infection from armpit sweat

Chris Callewaert et al. Front Med (Lausanne). .

Abstract

Detection dogs were trained to detect SARS-CoV-2 infection based on armpit sweat odor. Sweat samples were collected using cotton pads under the armpits of negative and positive human patients, confirmed by qPCR, for periods of 15-30 min. Multiple hospitals and organizations throughout Belgium participated in this study. The sweat samples were stored at -20°C prior to being used for training purposes. Six dogs were trained under controlled atmosphere conditions for 2-3 months. After training, a 7-day validation period was conducted to assess the dogs' performances. The detection dogs exhibited an overall sensitivity of 81%, specificity of 98%, and an accuracy of 95%. After validation, training continued for 3 months, during which the dogs' performances remained the same. Gas chromatography/mass spectrometry (GC/MS) analysis revealed a unique sweat scent associated with SARS-CoV-2 positive sweat samples. This scent consisted of a wide variety of volatiles, including breakdown compounds of antiviral fatty acids, skin proteins and neurotransmitters/hormones. An acceptability survey conducted in Belgium demonstrated an overall high acceptability and enthusiasm toward the use of detection dogs for SARS-CoV-2 detection. Compared to qPCR and previous canine studies, the detection dogs have good performances in detecting SARS-CoV-2 infection in humans, using frozen sweat samples from the armpits. As a result, they can be used as an accurate pre-screening tool in various field settings alongside the PCR test.

Keywords: COVID-19; GC/MS (gas chromatograph/mass spectrometry); acceptability analysis; axilla; detection dogs; odor; vaccination.

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Conflict of interest statement

CC is the founder of DrArmpit BV. AA and AM are founders of Arome Science Inc. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The reviewer A-LC is currently co-organizing a Research Topic with one of the authors DG.

Figures

Figure 1
Figure 1
Detection dog (Malinois shepherd) sniffing a sweat sample through a metallic cone during a training at the Training Center of Neerhespen (Federal Police, DACH).
Figure 2
Figure 2
Impact of sampling location and sampling time on marking by the six trained SARS-CoV-2 detection dogs during validation phase. (A) Impact of sampling location on percentage of marking by the detection dogs in the SARS-CoV-2 positive samples (from hospitals). (B) Impact of sampling location on percentage of marking by the detection dogs in the SARS-CoV-2 negative samples (from volunteers). (C) Impact of sampling location on percentage of hesitations by the detection dogs in the SARS-CoV-2 positive samples (from hospitals). (D) Impact of sampling location on percentage of hesitations by the detection dogs in the SARS-CoV-2 negative samples (from volunteers). (E) Impact of sampling duration on percentage of marking by the detection dogs in the SARS-CoV-2 positive samples (from hospitals).
Figure 3
Figure 3
Molecular exploration of differences between SARS-CoV-2-positive and SARS-CoV-2-negative sweat samples. (A) PLSDA plot indicates clear differences in metabolic background among the SARS-CoV-2-positive (red) and SARS-CoV-2-negative (green) sweat samples. (B) The plot shows the ratio of abundances of volatiles in SARS-CoV-2-positive versus SARS-CoV-2-negative sweat samples. Ratios higher and lower than one (i.e., volatiles that are enriched in SARS-CoV-2+ versus SARS-CoV-2- samples) are highlighted in red and green, respectively. Examples of important and recurrent annotated volatiles and their respective molecular related volatiles are depicted.
Figure 4
Figure 4
Results from the national survey on acceptability toward the use of SARS-CoV-2 detection dogs in practice. (A) Do you accept detection dogs to be used for this purpose? (B) Do you trust in the outcome of the SARS-CoV-2 detection dogs? (C) Which test would people trust more: the outcome of the SARS-CoV-2 detection dogs or the outcome of the qPCR test? (D) Is it ethical to use detection dogs for this purpose? (E) Is it organizationally possible to use detection dogs in real life? (F) Is it dangerous to use dogs for this purpose?
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