The Health Protection Agency said the latest case brings the total to 21. The patient, who is being treated at the University Hospital of North Staffordshire, is a man in his 70s.
Two patients being treated for the disease since the spate of illnesses began in the middle of July have died.
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Low pressure will keep the weather unsettled overnight and tomorrow with rain pushing continuing to push northwards.
Six-month-old Leena Belkadi and her sister Malak Belkadi, aged eight, both died from inhalation of fire fumes, an inquest has heard.
The true number of those believed to be dead or missing and presumed dead following the fire won't be known until the end of the year.