Those who did were taken to a private room at the Dubai
airport. A border official took a sample of sweat from the passenger’s armpit.
In another room, a trained K-9 sniffer dog smelled it to decide whether the
passenger was infected by coronavirus or not.
*****
Over the last few months, dogs have been intensively trained
in the USA, UAE, Chile, Finland, Australia, Germany, Argentina, Brazil and
Belgium. Most studies conclude dogs can sniff and detect the virus with over
95% accuracy. Chile trains Labradors and Golden Retrievers. Saudi Arabia Jack
Terriers. UK has Labradors and Cocker Spaniels.
Scientists at the London School of Hygiene and Tropical
Medicine are currently recruiting volunteers to help train dogs. Volunteers with
mild symptoms need to give samples of breath and body, wearing a mask for three
hours and nylon socks and t-shirt for 12 hours. The aim is to collect 325
positive and 675 negative samples to train dogs.
*****
Since April, the University of Pennsylvania has trained
eight Labradors and one Belgian Malinois. A dog is let into the room that
contains a giant horizontal metal wheel. The wheel has metal cans, each
containing urine samples from patients testing positive or negative. The Labrador
sniffs each can, and stops at the container with a positive sample.
Olfactory disease detection is an evolving field. We
know the simple mechanism of a breathalyzer for levels of alcohol. A dog’s nose
has 300 million receptors compared to 5 million in a human. Dogs can be trained
to smell drugs, explosives, some hidden cancers, diabetes, malaria and other
infections.
Changes in our health alter the way we smell. Spouses
of some patients with Parkinson’s have noted their partners smelling
differently. Human bodies give off a cocktail of chemicals known as VOCs
(volatile organic compounds) in sweat, saliva, urine, breath and sebum that
change when cells grow. When infected by a virus, some cells die and the smell
changes. Dogs don’t detect Covid, but they detect the cells dying because of
the virus infection.
To systematically train a dog to detect the novel
coronavirus, it takes 6-8 weeks if the dog is already trained to detect other
scents. A new dog needs 3-6 months. How does the dog know the object of
detection? Like in a circus, the dog is initially “bribed” for performance.
When the Labrador or German shepherd smells a “positive” can, it is given a pet
food - Kibble. At the “negative” can, nothing. Over the weeks, the Labrador realizes
the trainer is interested in finding the “positives”. The dog is also
interested, because it gets a kibble every time. After two months, it stops at
a positive can, and looks at the trainer to indicate victory. By this time, bribing
can stop.
In a single case, one Labrador made a mistake. It
stopped at a “negative” can. When investigated, it was found that the patient had
earlier tested positive, and the smell had lingered.
Like human beings, dogs also come with superior
ability, inferior ability and laziness. A
dog can sniff 250 people per hour. This is hard work. (It’s a dog’s life). Not
every dog manages this. The best ones are chosen for airports. After UAE, Saudi
Arabia will employ them soon at its international airport.
*****
Dogs are accurate, but require long training and
expensive maintenance. “Electronic noses” are now invented that successfully
detect toxic gases and explosives. Scientists believe they are the future.
Until then, airport authorities will continue to trust the noses of the
Labradors.
Ravi