Health officials are in the process of contacting British airline passengers who may have made contact with a passenger who has been hospitalised in the US with the often fatal MERS (Middle East respiratory syndrome).
The man, a non-British national, took a British Airways flight 262 on April 24 from Riyadh, the capital city of Saudi Arabia, to London, where he changed flights at Heathrow to fly to the US.
Public Health England said it has contacted UK passengers on the BA flight to London who were sitting in the vicinity of the affected passenger and is working with US health authorities to contact any British passengers on the April 24 onward flight to Chicago, American Airlines Flight 99.
It said that the risk of the infection being passed to other passengers "is extremely low" but was contacting the passengers "as a precautionary measure."
Any UK based passengers on Flight 262 on April 24 who have since become unwell or experienced respiratory symptoms, such as shortness of breath, are advised to contact NHS 111.