AN OUTBREAK OF a rare and deadly form of meningitis has hospitalised 26 people and killed four people across five states  in America.

All the cases involved patients who received steroid injections.

Eighteen of the cases are in Tennessee where a Nashville clinic received the largest shipment of the steroid suspected in the outbreak. The drug was made by a specialty pharmacy in Massachusetts. It has since issued a recall.

Three cases have been reported in Virginia, two in Maryland, two in Florida and one in North Carolina. Two of the deaths were in Tennessee; Virginia and Maryland had one each, the Centres for Disease Control and Prevention said.

More new cases are almost certain to appear in the coming days, said Tennessee Department of Health Commissioner John Dreyzehner. Cases in that state began in July and five new cases were confirmed over the past 24 hours, he said Wednesday.

Investigators have been looking into at least three different products used for the back injections that could have been tainted by the fungus that appears to be behind the illnesses. None of the products have been ruled out. However, the primary suspicion is on steroid medication, which is commonly used for back pain.

The Food and Drug Administration identified the maker of the steroid as the New England Compounding Center, a specialty pharmacy in Framingham. Last week, the company issued a recall of three lots of the steroid. Company officials could not be immediately reached Wednesday afternoon by telephone; the company’s website was unavailable.