key: cord-317632-2bjzn6p7
authors: Jones, Robert T; Guest, Claire; Lindsay, Steve W; Kleinschmidt, Immo; Bradley, John; Dewhirst, Sarah; Last, Anna; Logan, James G
title: Could bio-detection dogs be used to limit the spread of COVID-19 by travellers?
date: 2020-08-12
journal: J Travel Med
DOI: 10.1093/jtm/taaa131
sha: 
doc_id: 317632
cord_uid: 2bjzn6p7

nan

The COVID-19 crisis has not only deeply affected those with SARS-CoV-2 infections, and their families, but it has also had an unprecedented global economic impact. The travel and tourism sectors have been particularly hard hit, with aircraft grounded, hotels closed, and travel restrictions and quarantines introduced around the world. The United Nations' World Tourism

Organization predicts there will be declines of 58% to 78% in international tourist arrivals this

year. 1

There are increasing numbers of COVID-19 cases in many countries, including Australia, Brazil, France, Spain, and Japan. Whilst some of the apparent surge may be a result of increased testing, there is a concern of a second wave. In the Spanish flu pandemic of 1918, which killed 50-100 million people, it was the second wave that produced the greatest number of deaths. 2

As a defence against a second wave of COVID-19, it is critically important that measures are put in place to prevent the importation of new cases from countries with a high incidence of 

Screening travellers for COVID-19 at airports is an attractive option that could prevent imported infections, and may reduce the need to enforce quarantine on travellers. Infrared thermal image scanners have been used previously during epidemics, but modelling studies indicate that, even under best-case assumptions, thermal screening will miss more than half of infected people. 3 Many cases are fundamentally undetectable through these scanners because infected individuals may be presymptomatic or do not have a fever at the time of scanning. There remains a need for a sensitive, rapid, non-invasive means of screening large numbers of asymptomatic people, both at departure and on arrival into ports. Previous work with bio-detection dogs suggests that highly-trained dogs may offer a viable solution to COVID-19 detection.

There is evidence that respiratory infections cause the release of specific odours. The analysis of volatiles liberated in breath, urine, faeces and sweat has shown that microbial infections are associated with the production of specific volatile organic compounds (VOCs), and that the ratio of these VOCs differs depending on the infectious microorganisms. 4 This area of research has led to interest in using volatiles as biomarkers of infectious diseases, such as cholera.

Other, more recent work by the authors, demonstrated that asymptomatic malaria infection also causes changes in VOCs, which vary throughout the infection. 5 Further work by the same team demonstrated the use of trained dogs in identifying malaria parasites in asymptomatic children. 6 The dogs were trained using odour samples collected on socks worn by confirmed positive asymptomatic or negative children in The Gambia. The dogs were then trained to distinguish between the odours of socks worn by infected and uninfected children. Once training was

completed, a second set of specimens was used in a double blinded study to determine the specificity and sensitivity of detection. The study demonstrated that dogs could identify malaria with a degree of sensitivity and specificity broadly in line with the World Health Organization's criteria for the procurement of rapid diagnostic tests. 6 In March this year, we commenced a prospective three-phase study in the UK involving collection of body and breath odour samples from more than three hundred asymptomatic and mildly symptomatic participants. Phase 1 is a proof-of-principle study to demonstrate that medical detection dogs can be trained to identify asymptomatic or mild symptomatic infections with SARS-CoV-2 with high sensitivity and specificity. Phase 2 is an assessment of the capability of the trained dogs to detect people with asymptomatic or mildly symptomatic SARS-CoV-2 infection. This important step will move the research team closer to deployment of dogs, and will require the sensitivity and specificity of the dogs to be assessed at COVID-19 test centres where they can sniff individuals waiting to donate swab samples for formal diagnosis. If bio-detection dogs prove to be effective in the detection of asymptomatic or mildly symptomatic individuals, there is enormous potential for them to be used at key entry points, such as airports and sea ports, to support efforts to screen departing or incoming passengers, which is crucial for ensuring safer, and fully operational, global travel in the future, and for any elimination strategies. Each trained dog can screen up to 250 people in an hour and they could be stationed before entering the terminal building, at the security checkpoint for outbound passengers and staff, and at border control for inbound passengers. Positive individuals and their contacts could then isolate to prevent the spread of infection to others. This will be of significant benefit to the economy and the control of the pandemic, as it could eliminate the need to keep 

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Estimated effectiveness of symptom and risk screening to prevent the spread of COVID-19

The scent of disease: volatile organic compounds of the human body related to disease and disorder

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Trained dogs identify people with malaria parasites by their odour

Cellular scent of influenza virus infection

Real-Time Detection of a Virus Using Detection Dogs

Scent dog identification of samples from