Scent dogs reliably detect coronavirus from skin sticks
Newswise – A recent study by the University of Helsinki and Helsinki University Hospital confirmed that odor detection dogs can be taught to identify coronavirus-infected individuals from skin swabs. In the experimental arrangement at Helsinki-Vantaa Airport, the accuracy of the dogs in identifying the samples was 92 per cent.
Rapid and accurate identification and isolation of patients infected with coronavirus is an important part of global pandemic management. The current diagnosis of coronavirus infection is based on a PCR test that accurately and sensitively identifies coronavirus from other pathogens. However, PCR tests are not suitable for screening large masses of people due to, among other things, their slow results and high cost.
Researchers from the University of Helsinki’s Faculty of Veterinary Medicine and Medicine and Helsinki University Hospital jointly designed a triple-blinded, randomized, controlled research system to test the accuracy of trained odor detection dogs. The study also analyzed factors that may interfere with the ability of dogs to recognize a positive sample.
The three-dimensional study has now been published in the journal BMJ Global Health. The study provides valuable information on the use of stray dogs in the fight against a pandemic.
Correct identification in more than 90% of samples; only small differences in accuracy between dogs
In the first phase of the study, dogs were taught to distinguish skin samples from coronavirus patients from negative volunteers. After a training period of several weeks, the dogs moved from the training center to Helsinki-Vantaa Airport for the next stages of the study.
In the second phase of the study, four trained dogs performed a validation test to demonstrate their ability to discriminate. During the experiment, each dog was presented with a series of 420 samples over seven days. Because multiple replicates had been collected from each donor, each dog received an identical set of 114 coronavirus patient samples and 306 control samples. The coronavirus status of all sample donors was confirmed by PCR. During each test day, the dog sniffed 20 specimen traces, each containing three specimens, and the traces were presented in random order.
Dogs correctly identified samples 92 percent of the time. When their sensitivity to detect a positive coronavirus sample was 92 percent, their specificity was 91 percent. Only small differences in accuracy were observed between the four dogs. Coronavirus infection caused by viral variants was the single largest factor contributing to the misidentification of dogs.
The study confirms previous reports that stray dogs can identify individuals infected with coronavirus.
“Our study arrangement was of a high scientific standard. Sample sizes were large enough, and all dogs smelled identical samples, allowing comparison of their performance. Dogs also had to successfully demonstrate sets of samples that contained only negative samples, an important feature in screening individuals. Another significant advantage was that samples were collected from outpatients instead of hospital patients. In addition, the testing was performed under real-life conditions and not in a laboratory, ”says the head of the department DogRisk Research Group and Associate Professor of Clinical Trials in Companion Animals Anna Hielm-Björkman From the University of Helsinki.
“I was particularly impressed that the dogs did less well in the samples we had collected from patients suffering from a disease caused by a variant of the coronavirus. The explanation is simple: the dogs were originally trained with the original wild-type virus, so they did not always recognize variant samples as positive. This reveals their incredible ability to discriminate, ”he says Anu Kantele, Professor and Chief Physician of Infectious Diseases at the University of Helsinki and Helsinki University Hospital.
Great help from smelling dogs at airports and ports
The third phase of the study was conducted by screening real-life passengers and staff at Helsinki-Vantaa Airport. Scent dogs correctly identified 98.7 percent of negative samples. The small number of coronavirus-positive samples in real-life tests prevented the correct evaluation of dog performance with positive samples. However, based on positive “work motivation samples” given to dogs on a regular basis during this part of the study, the performance of correctly identified positive samples was also estimated to be 98.7%. Work motivation samples are naive samples collected in advance from PCR-positive patients but not previously smelled by dogs. They are given to dogs at regular intervals to maintain their interest in the target odor in situations and environments where the proportion of positive samples is otherwise very small.
“Scented dogs can provide an invaluable tool for limiting the spread of the virus during a pandemic, such as serving in airports and seaports. Anu Kantele says.
“Our team of researchers will continue to explore how smelling dogs can best help our society. We hope that this recently published study will help allocate funds for the development of this new ‘tool.’ Björkman says.
The study was carried out with the support of the Finnish Cultural Foundation, Svenska Kulturfonden i Finland, the Academy of Finland, the Jane and Aatos Erko Foundation, the Finnish Medical Association, the Veterinary Hospital Chain Evidensia, the Nose Academy, Finavia’s City of Vantaa and Deputy Mayor Timo Aronkytö. Anna Hielm-Björkman’s research group has also been supported by private donations in a koronadog fundraising campaign organized jointly by the Kennel Club and the University of Helsinki. The dogs were originally trained at the NGO Wise Nose Training Center.