Many research groups around the world are training dogs to detect people infected with COVID-19. In France, there are Covidog Project of the University of Strasbourg and the project of the French National Center for Scientific Research (CNRS).
Why can dogs detect people with COVID-19?
The inside of the dog’s nose is covered with 200 million olfactory cells (humans have only 5 million olfactory cells). Thanks to these olfactory cells, dogs smell very sensitive.
The SARS-CoV-2 virus does not have a special odor. In contrast, people infected with the SARS-CoV-2 virus secrete specific molecules in the air called “volatilized organic substances” (volatilomes).
Virologist Christophe Ritzenthaler – CNRS research director and researcher at the Institute of Plant Molecular Biology, explained: “The virus reprograms the cell, causing dramatic changes in the metabolism of the cells. cells. Therefore, infected cells do not release the same molecules as healthy cells.
From there, the dog can learn to recognize the “smell” of the disease from the infected person as well as the infected person not showing symptoms.
Use polymer to grab molecules
In order to train dogs, it is necessary to disperse molecules in the air.
The Strasbourg startup Biodesiv designed special tubes containing a polymer polymers that capture volatile molecules and then release them gradually.
“When we put this polymer next to infected cells, we can get the smell from the infected cell without risk of infection. Therefore, neither dog nor trainer can be infected,” explains expert Ritzenthaler. virus infection during training “.
The Alfort National School of Animal Health in Maisons-Alfort (France’s Val-de-Marne province) is running a project called Nosaïs-COVID-19.
Dogs are led to metal racks. In each stand contains a human sweat sample taken under the armpit with a gauze.
Samples containing no viral load were obtained from samples taken from COVID-19 positive patients in hospitals. Your dog’s job is to detect an infected person by sniffing these metal racks.
Several barracks on Corse Island (Ajaccio, Bastia and Porto Veccio) tested the device in the summer. Results show that the device can screen hundreds of people.
Problems need to continue to improve
At the end of August 2020, the National Academy of Medicine and the French Academy of Veterinary Medicine released a press release evaluating the very promising results of the initial study using dogs to detect COVID-19 infections.
However, there is a need to “supplement scientific evaluation and development of new trials for implementation at the earliest possible time” and “define good practice rules”.
In addition, the researchers also have to answer questions including the percentage of false positives such as false positives or false negatives, and exactly what molecules the dog identifies.
The two institutions mentioned above noted that with the increasing number of tests needed, using a sniffing dog will reduce the waiting time for RT-PCR test results too long, especially in suspected cases and cases. case of exposure to an infected person.
The dog’s confidence rate is very high
Recently, a veterinary research group of Hanover University (Germany) has published research in the specialized journal BMC Infectious Diseases that 7 dogs performed a total of 10,388 tests and correctly detected the word 82.6% -96%.
Although the number of samples tested is small, the above study shows that the confidence rate of dogs is very high. However, it is still necessary to continue research to ensure the effect does not change.
Dog sniffing is especially helpful for group screening such as seniors in nursing homes or passengers boarding planes or trains.