Dogs at Helsinki airport that have been trained to detect Covid-19 are picking up infections in people at a very early stage and before the disease can be detected by the official laboratory tests. This is a remarkable finding. There was some concern initially because the dogs were picking up infections in people but when laboratory samples were tested in the laboratory they were found to be negative for the disease. But then the people developed the disease later proving that they were in fact positive and that the laboratory tests were false negatives. It also proves that dogs are better at testing for coronavirus than laboratory tests. The laboratory tests being used are polymerase chain reaction tests (PCR).
There are three coronavirus-sniffing dogs posted at Helsinki airport and they are: Miina, Kossi and Valo. The extraordinary aspect of this is that the initial negative tests were found to be positive a week later so these dogs were picking up the viral infection a week in advance. It isn’t just the Finnish researchers who are reporting this finding. At a conference for the medical detection dogs community, it was discovered that all those involved are having the same experience namely that their dogs are better at spotting Covid-19 than the conventional biological tests.
The polymerase chain reaction test is meant to be the gold standard but the dogs are better than it. The trouble is you can’t validate the dogs’ findings immediately because, as mentioned, they are in advance of conventional testing. We know that dogs have a fantastic ability to detect disease or indeed almost anything through their sense of smell but this finding is remarkable. The fact is that most diseases have an odour. This is because the body’s metabolism changes because of the presence of the disease, which causes a change in body odour.
Science cannot yet recreate instruments as exquisitely sensitive as their noses – Prof Logan from the London School of Hygiene and Tropical Medicine.
Prof Logan is working with the charity Medical Detection Dogs, a UK organisation and they hope that they will have the same success as the Finish dogs. The beauty of dogs is that they can work in different environments and produce an instant result. Individuals walking through airports can be screened even when they’re moving. People can be pulled out of the queue and then tested if a dog indicates that they are carrying the disease.
The downside is that it takes a long time to train dogs to do this and therefore they cannot be a complete solution. Also, dogs tend to detect people who have recovered from the infection because their noses are so sensitive.
Scientists are trying to build machines which can recreate the sensitivity of a dog’s nose. The PCR test produces false negative sometimes which is a weakness whereas the dogs do not have this weakness. They are much more accurate than any PCR at the moment. PCRs are about 70% accurate whereas the dogs never go under 100% said Dr Anna Hielm-Bjorkman who is running the Finish coronavirus-sniffing dog group.
Source: The Times.