Google searches for symptoms such as diarrhoea and abdominal pain could act as an early warning for a coronavirus outbreak, a study has revealed.
Academics found there was a surge in coronavirus cases roughly three to four weeks after a spike in online searches for the symptoms.
In New York, one of 15 regions examined in the study, searches for 'diarrhoea' almost doubled three weeks before the city's cases of Covid-19 soared.
The NHS does not currently recognise diarrhoea as being a tell-tale sign of Covid-19, contradicting their colleagues in the US.
It says only a fever, a new cough and a loss of taste and smell are symptoms of the virus, meaning thousands of Britons who don't experience those effects may fail to self-isolate and get tested during the early stages of their infection.
Scientists have already called for diarrhoea to be added to the list of symptoms for children in Britain, after their ability to spot the disease in youngsters rose from 76 to 97 per cent when it was included in the symptoms list.
Diarrhoea could be an early warning sign of coronavirus. A study found that searches for this rose before an outbreak of coronavirus was detected in their area
The ability to detect children who had coronavirus rose from 76 per cent to 97 per cent when stomach and gut pains were included with the official NHS symptoms, say researchers (stock)
What the NHS says:A high temperature New continuous cough Loss of taste or smell
What other symptoms are there?
As many as 16 other symptoms of coronavirus have also been identified, although they are yet to be listed by the NHS.
The Center for Disease Control (CDC) in the US updated its list back in May to include these symptoms:Shortness of breath or difficulty breathing Fatigue Muscle or body aches Headache Sore throat Congestion or runny nose Nausea or vomiting Diarrhoea
The UK's Covid symptom app says it has additional several further warning signs of the disease.
It has done this by asking more than 3.9 million people to report daily how they are feeling.
When they feel unwell they are asked to report the symptoms. Those that test positive for coronavirus then tell the app, allowing it to reveal less-well-known signs of the disease. It adds the following:Skin rash Hives Delirium Abdominal pain Chest pain Hoarse voice Eye soreness Dizziness or light-headed
The study, carried out by Massachusetts General Hospital in Boston, used Google Trends to monitor digital queries for 'diarrhoea', 'loss of appetite' and 'loss of smell' made in 15 states between January 20 and April 20.
It revealed a correlation between searches for these terms and a rise in coronavirus cases almost a month later.
The five states with the strongest correlation were New York, New Jersey, California, Massachusetts and Illinois.
The research was published in the Journal Clinical Gastroenterology and Hepatology.
Writing in the study Dr Kyle Staller, a gastroenterologist at Massachusetts General Hospital, said: 'Gastrointestinal symptoms appear to be a harbinger of Covid-19 infection.
'Google Trends may be a valuable tool for predicting geographic