Sniffer Dogs: Detecting Scents At Airports

Airport sniffer dogs are trained to detect a variety of substances and organisms, including illegal drugs, explosives, and infectious diseases. They possess an extremely acute sense of smell, allowing them to identify distinct volatile organic compounds released during metabolic processes in the body. Recent research has found that these dogs can accurately detect SARS-CoV-2 infections in airport passengers, with a success rate of around 92%. This method has been proposed as an efficient way to screen incoming travellers during a pandemic, particularly when resources are limited. Additionally, in the case of South Korea, a sniffer dog named Ceco was deployed at Incheon International Airport to detect bed bugs after the Paris Olympics, showcasing the versatility of these canine workers.

SARS-CoV-2 infection

Sniffer dogs have been used to detect SARS-CoV-2 infections in several countries. In Australia, a trial was conducted at Adelaide Airport, where six labradors were used to detect COVID-19 cases among incoming travellers by identifying their scent. Similar trials have been conducted in Paris, where dogs were used to screen 335 individuals at testing centres, with a 97% accuracy rate.

The use of canine detection for SARS-CoV-2 infections has several advantages. It is a non-invasive method that provides immediate and reliable results. It can also be used to screen large numbers of people quickly, making it an effective tool in crowded locations such as airports, stadiums, and public events.

However, there are also some limitations to using sniffer dogs for SARS-CoV-2 detection. One concern is the fear of dogs exhibited by a significant number of individuals. Additionally, there is a risk of dog contamination, which is not possible with other testing methods. Furthermore, it is unclear whether canine detection is specific to SARS-CoV-2 or if it can detect all coronaviruses.

To address these limitations, further studies are being conducted to evaluate the effectiveness of direct sniffing by dogs for mass pre-testing in various settings, including airports, harbours, railway stations, cultural activities, and sporting events. These studies aim to improve the accuracy and reliability of canine detection as an alternative to antigenic tests.

It is important to note that SARS-CoV-2 has been detected in dogs, with several cases reported worldwide. Most infected dogs are asymptomatic, with low viral loads. However, there have been cases of symptomatic infections, including respiratory, gastrointestinal, and cardiac complications, some of which have been severe. The transmission is presumed to be from human-to-animal contact, and it is unclear if infected dogs can transmit the virus back to humans or other animals.

Bed bugs

Dogs possess an extraordinary sense of smell, capable of detecting scents at concentrations as low as parts per trillion. They have up to 300 million olfactory receptors, allowing them to discern individual odours within a complex mixture. This heightened sense of smell makes them ideal for pest detection tasks like identifying bed bugs.

During an inspection, the handler guides the dog through the space, allowing it to sniff furniture, bedding, baseboards, and other areas where bed bugs may hide. The process is typically swift, with dogs covering a room in minutes. When a dog detects the scent of bed bugs, it will alert its handler through a trained response, such as sitting, lying down, or pawing at the spot. The handler then confirms the findings and coordinates follow-up steps, such as visual verification or pest control measures.

Bed bug detection dogs have become a trusted solution in pest control, complementing visual inspections and enhancing extermination strategies. They are highly accurate, with studies reporting accuracy rates between 80% and 95%. However, their effectiveness depends on factors such as the thoroughness of the dog's training, the handler's expertise in interpreting the dog's alerts, and environmental factors such as strong odours or distractions.

Bacterial infections

While the main focus of sniffer dogs at airports is to detect illegal substances, they can also be trained to detect bacterial infections. These dogs are trained to recognise a specific odour in sweat samples, which indicates the presence of a bacterial infection.

Sniffer dogs have been used to detect SARS-CoV-2, the virus responsible for COVID-19, at airports around the world. Their keen sense of smell allows them to pick up scents at extremely low levels, far exceeding the capabilities of mechanical techniques. In fact, research has shown that dogs can detect SARS-CoV-2 with an accuracy of up to 99%.

For example, at Helsinki-Vantaa International Airport in Finland, four dogs were deployed to sniff out incoming passengers between September 2020 and April 2021. These dogs correctly identified 99% of PCR-negative swab tests and three out of four PCR-positive cases.

Similarly, at Miami International Airport, a pair of dogs named Cobra and One Betta were trained to detect COVID-19 among airport employees. They achieved an impressive accuracy rate of 99.4% and 98.1%, respectively.

The use of sniffer dogs for bacterial infection detection has the potential to save time and resources, especially in the early stages of a pandemic when other resources may not be readily available. Their ability to detect infections through scent can even identify pre-symptomatic cases, making them a valuable tool in preventing the spread of infectious diseases.

Viral infections

Airport sniffer dogs are trained to detect viral infections, such as the SARS-CoV-2 virus responsible for COVID-19. Research published in the journal BMJ Global Health in May 2022 found that these dogs could accurately identify airport passengers infected with SARS-CoV-2, with a diagnostic accuracy of 92%. The dogs' performance varied only slightly, with the best dog achieving 93% sensitivity and 95% specificity, while the worst achieved 88% sensitivity and 90% specificity.

The high negative predictive value (NPV) of sniffer dogs supports their use in screening, particularly in the early stages of a pandemic when other resources may be scarce. Their acute sense of smell allows them to detect distinct volatile organic compounds (VOCs) released during various metabolic processes in the body, including those generated by viral infections. This capability can help exclude people who do not need a PCR swab test, saving time and resources.

In a real-life setting at Helsinki-Vantaa International Airport in Finland, four sniffer dogs screened 303 incoming passengers between September 2020 and April 2021. The dogs correctly identified 296 out of 303 (98%) of the samples, with only one false negative and two samples not sniffed. The dogs' performance was not affected by the presence or absence of symptoms, as they correctly identified 25 out of 28 (89%) positive samples from asymptomatic individuals.

While the dogs' ability to detect SARS-CoV-2 is impressive, researchers acknowledge that dogs trained to detect other substances may sometimes mistake those scents for SARS-CoV-2. Additionally, the required storage period for training and spiked samples may impact the viability of the VOCs. Nevertheless, the potential for retraining dogs to detect new variants in a matter of hours is promising.

Parasitic infections

Sniffer dogs are trained to detect distinct volatile organic compounds released during various metabolic processes in the body, including those generated by bacterial, viral, and parasitic infections. They can be trained to detect parasitic infections within weeks, with a high degree of accuracy.

Dogs have an extremely acute sense of smell, and can pick up a scent at levels as low as one part per trillion, far exceeding any available mechanical techniques. This makes them ideal for detecting parasitic infections, especially in the early stages of an outbreak when other resources may not be readily available.

In a real-life trial, four dogs were used to sniff out 303 incoming passengers at Helsinki-Vantaa International Airport, Finland, between September 2020 and April 2021. Each passenger also took a PCR swab test, and the sniffer dogs' results matched 296 out of 303 (98%) of the real-life samples. This high level of accuracy supports the use of sniffer dogs for screening incoming passengers at airports to prevent the spread of parasitic infections.

Sniffer dogs can also be used to detect other issues at airports, such as bed bugs. For example, South Korea deployed a bed bug sniffer dog at Incheon International Airport to reduce the risk of incoming travellers bringing in bed bugs after an outbreak in Paris. The dog, a two-year-old beagle named Ceco, is the only canine in the country trained to detect the odour of pheromones emitted by bed bugs.

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