The number of meningitis cases linked to steroid injections is rising with 12 confirmed deaths, including a British-born woman.
US authorities fear there could eventually be as many as 600 cases of a rare fungal meningitis linked to a steroid commonly used to ease back pain.
A 70-year-old man from Florida became the 12th confirmed death from the outbreak late on Tuesday.
As many as 13,000 people received the steroid shots from July to September and ten states have been affected so far: Florida, Indiana, Maryland, Michigan, Minnesota, New Jersey, North Carolina, Ohio, Tennessee and Virginia.
Figures released by the Centres for Disease Control and Prevention (CDC) show there are currently around 120 cases in the US.
In Tennessee, where there have been six deaths and 39 reported cases, state health officials estimate that around 5% of patients who received injections then contracted meningitis.
Based on that rate of infection, the number of confirmed cases nationally could grow to about 650.
But it could be an anxious wait for many thousands as the incubation period of the disease is up to a month.
Among them is George Cary from Howell, Michigan whose British-born wife Lilian Cary was one of the 11 victims so far.
The 67-year-old was originally from Stoke-on-Trent. Her husband described her as “a little Brit” with “attitude and spunk”.
Mr Cary was treated in September with the same suspect medication and is now awaiting the results of a spinal tap taken on Saturday.
“I am standing here,” Cary said. “I’m fine right now. I’m waiting to see if anything develops.”
The steroid linked to the outbreak has been recalled, and health officials have been scrambling to notify anyone who may have received an injection of it.
The Massachusetts pharmacy that made it has said it is co-operating with investigators.
The New England Compounding Centre announced the recall on Saturday, saying the move was taken because of the risk of contamination.
It said there was no indication any other products have been contaminated.
The Food and Drug Administration (FDA) previously told health professionals not to use any products distributed by the centre.
The outbreak has alarmed federal officials and highlighted a gap in the regulation of what are known as pharmacy compounders, which are facilities that take drug ingredients and package them into medications and dosages for specific clients.
The FDA regulates only the ingredients and not the compounders, which are subject to a patchwork of state oversight.
Meningitis is caused by the inflammation of meninges, which are protective membranes covering the brain and spinal cord.
Fungal meningitis is not contagious like its more common viral and bacterial counterparts.