A health spa is the "likely source" of an outbreak of Legionella infection which has left nine people in hospital, Public Health England (PHE) has said.
Fourteen people who attended Healax Salt Caves in Bournemouth in June have contracted either Legionnaire's Disease or the less serious Pontiac fever.
A further 39 people who reported symptoms have not had infections confirmed by laboratory tests.
The nine worst-affected patients are now recovering at home.
Wendy Brimicombe, 63, said she and a friend both contracted Pontiac fever after visiting the spa on 10 June.
"When I got home I had a headache, was sick and felt like my chest was being crushed," she said.
Ms Brimicombe said she slept for more than 24 hours, not realising that she had missed work.
"I live alone. It's really frightened me," she said.
PHE England said it had given health advice to other customers and to local residents.
Dr Fiona Neeley from PHE said: "We understand that there will be concern among people who visited Healax Salt Caves and spa.
"Thankfully, in all cases of illness that have been reported to Public Health England to date, those affected are now recovering from their illness.
"There are no ongoing risks to health for the wider population in relation to this incident."
She said the business owner and health officials had "acted quickly" to ensure that any further risk was controlled.
The affected customers visited the spa between 1 June and 18 June, PHE said.
The business in Kinson Road has been closed until further notice, its Facebook site said.
A repossession notice has been posted on the door.
Therapies offered at the centre include a salt water hot tub and a "salt cave" with a salt-covered floor and walls made from salt blocks.
- Legionella bacteria live in natural and and man-made water systems
- They become a health risk when maintenance problems occur in systems such as spa pools
- Legionnaire's disease is a serious lung infection which can cause pneumonia
- Men aged over 50, smokers and ex-smokers and patients with underlying medical conditions are most at risk of the disease
- Pontiac fever is a mild flu-like illness also caused by Legionella bacteria
- Symptoms of both conditions include fever, coughs, muscle aches and fatigue
(Source: Public Health England)