A hot tub is thought to have been the probable source of an outbreak of Legionnaires' Disease, the Health Protection Agency has said.
Based at JTF Warehouse in City Road, Fenton, Stoke-on-Trent, samples taken from the hot tub were found to have an unusual strain of legionella bacteria, which matched that of the strain taken from patients with the illness.
Dr Sue Ibbotson, regional director of the Health Protection Agency (HPA), West Midlands, said the organisation has taken detailed histories from those with Legionnaires and 17 of the 18 confirmed cases visited the warehouse in the two weeks before they fell ill.
One patient died after being affected by the disease, though a cause of death has yet to be revealed.
The HPA emphasised that while a probable cause has been identified, investigations are still ongoing.
Environmental Health specialists from the Health and Safety Executive (HSE) and Stoke-on-Trent City Council have taken and continue to take samples from sites across Stoke.
An HSE spokesman said: "HSE continues to inspect premises where we are the enforcing authority and will do so until we have eliminated those sites from our investigations and are sufficiently assured there are no other possible sources."
The samples from the hot tub at JTF Warehouse were confirmed by the Health Protection Agency's specialist laboratory in Colindale as being an unusual strain legionella bacteria. The company is fully co-operating with the investigation and decommissioned the hot tub on July 24.
Dr Ibbotson said: "We have identified the probable source of the Legionnaires' Disease outbreak in Stoke. We have the evidence from DNA fingerprinting of samples from the hot tub and the patients being caused by the same previously unseen strain of legionella.
"The HPA also took detailed histories from the confirmed cases and we know that 17 of the 18 confirmed cases visited this warehouse in the two weeks before they fell ill. Added to that we know that spa pools are known to be effective mechanisms for spreading legionella infection. We may still expect to see new cases of Legionnaires' Disease related to this outbreak."