German study finds dogs can sniff out COVID-19 patients with infectious microbe, claims 94% success rate
Dogs are also shown to be able to detect various diseases including cancer, malaria, and various kinds of bacterial and viral infections.
Early detection followed by isolation is one of the best ways to stop the spread of COVID-19. However, the asymptomatic and presymptomatic transmission of the disease poses a big challenge here. Since the virus can spread easily in a crowded setting, such people can unknowingly lead to local outbreaks.
Now, a group of researchers at the University of Veterinary Medicine Hannover, Germany, claim that dogs can sniff out coronavirus patients in a crowd with high precision.
Previously Col PK Chug, Consulting director, at the police K9 cell at the Ministry of Home Affairs has claimed that dogs can sniff out coronavirus patients from their body odour -- if they are trained to do so that is. However, the screening would only be effective if they have more than a 90 percent success rate.
The latest study published in the peer-reviewed journal BMC Infectious Diseases suggests a 94 percent detection rate. Based on their findings, the researchers say that we can use trained dogs to find coronavirus patients in public areas like airports and mass gatherings and reduce the spread of the disease.
Findings of the study
For the latest study, the researchers at the University of Veterinary Medicine Hannover trained eight dogs for one week to identify the saliva and or respiratory secretions of confirmed COVID-19 patients.
About 100 µL of samples were put on a cotton pad and the pad was put in a 4 mL glass tube for identification. The samples were put along with known negative samples in such a way that the dog is not directly exposed to it but can sniff it out through a grid.
A total of 1,012 samples were randomised and presented to the dogs. Out of these, the dogs had an average detection rate of 94 percent with 157 positives, 792 negatives, 33 false positives and 30 false negatives. The testing specificity was 96.34 percent and sensitivity was 82.63 percent.
Test sensitivity refers to the ability to correctly identify true positives and specificity refers to the ability to correctly identify true negatives. As per the study, an RT-PCR has a false positive rate of 2.3-6.9 percent.
Strong sense of smell
Dogs are known for their strong sense of smell. Humans have been training and using dogs to identify and differentiate odours such as various drugs, blood and other things for many years. The olfactory sense of a dog is said to be about 10,000 to 100,000 times stronger than humans. They can even detect a substance at a concentration of one part per trillion -- meaning the size of one droplet of water in an Olympic-sized swimming pool.
Dogs are also shown to be able to detect various diseases including cancer, malaria, and various kinds of bacterial and viral infections. It is suggested that in all of these conditions, the infectious microbe or the human body produces certain substances that a dog can sniff out and can be trained to recognise.
Things to consider
One of the important things that the study suggested was the possibility of dogs becoming the spreader of the infection. It is not known whether dogs can transmit the infection to humans although human to animal transmission has been seen. Also, there is concern about the effect of the virus on a dog’s sense of smell. If a dog does get the disease and it somehow affects its sense of smell, the whole practice may be useless.
Hence, more studies are needed to find answers to all these questions before dogs can be considered to find COVID-19 positive people in crowds.
For more information, read our article on Contact tracing: what is it and how does it help.
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