by John M. Simpson.
As we reported previously, a study conducted by the National Veterinary School in Alfort, France, suggested that dogs trained in some form of olfactory detection, such as explosives or narcotics, could be trained to detect, with reasonable accuracy, the SARS-CoV-2 virus in samples of human axillary perspiration (underarm sweat), thus suggesting the potential of sniffer dogs as a screen for the COVID-19 disease. That approach has been deployed at the Dubai International Airport (DXB).
A video released by the Emirates News Agency illustrates the procedure. Sweat samples are collected from incoming passengers individually and sent to an isolation room for processing. At that point, a jar containing the passenger’s sample is connected to one of five cone-like structures which resemble the structures that were utilized in the Alfort study. Apparently, four of the cones do not contain a positive sample. The dog is then brought into the room and asked to indicate which of the cones has the positive sample. A spokesperson on the video asserts that the results are available in less than one minute.
The sniffer dog procedure appears to be a supplement to the primary means of COVID-19 screening at DXB. Currently, the airport requires all arriving citizens, residents, tourists and transient passengers to obtain a COVID-19 negative certificate based on polymerase chain reaction (PCR) testing. The certificate is valid only for the 96-hour period following the PCR test. Individuals on flights departing to the European Union or United Kingdom must carry the same certificate.
The dogs could be an important extra measure. While the Alfort study was proof-of-concept, the results (obtained with 8 dogs and 15 to 68 trials per dog) were interesting. The dogs succeeded in detecting the positive sample at rate that ranged from 85 to 100% with a likelihood of only 14 to 33% that the success rate was due to chance alone. Even more interesting was the fact that the dogs identified as positive two cases that conventional testing had indicated were negative. When the patients were retested, the dogs were proven to be correct. So, sniffer dogs may be a helpful adjunct in winnowing out negative certificates that are based on false negative results.
The use of sniffer dogs at DXB is apparently the first time this technique for COVID-19 detection has been employed at any airport in the world.