The flare-up has caused 247 cases across 15 states, the Centers for Disease Control and Prevention reported on its website.

The southern state of Tennessee remains the hardest hit with 61 cases and eight deaths, followed by Michigan with 48 cases and three fatalities.

Other affected states include Indiana, Maryland and Florida.

The tainted steroid -- typically injected into the spine to treat back pain -- has been traced to the New England Compounding Center in Massachusetts, which has since shut down its operations and recalled all of its products.

Officials have said that as many as 14,000 people in 23 states could be at risk and that it could be weeks or even months before authorities have a final tally of the infections, due to the disease's long incubation period.

The rare strain of the disease, which inflames the protective membranes covering the brain and spinal cord, requires a lengthy hospital stay and intravenous medications. However, it is not contagious in this form.