(NEW YORK) -- It's been more than a month since the 42-day risk period for contracting fungal meningitis from tainted steroid injections ended on Nov. 7, but new meningitis cases, spinal infections and other complications continue to arise, even for patients who have already been treated and sent home.
"Here's the perplexing issue," said Dr. Tom Chiller, the deputy chief of the Centers for Disease Control and Prevention's mycotic diseases branch. "Why are we getting people that early on who are presenting with rip-roaring meningitis, but now, they're presenting 100 days later with focal infections only? Why the difference? We don't know."
The CDC reported five new meningitis cases, 39 new spinal infections without meningitis, and three new joint infections within the past week. One more person has died over the same time period, bringing the death toll to 37.
Up to 14,000 people received the tainted injections produced at New England Compounding Center in Framingham, Mass, which recalled all products and shut down on Oct. 6. It is now being investigated by the Food and Drug Administration, even though its oversight usually falls under its state's pharmacy board's jurisdiction.
NECC's owner Bill Cadden invoked the Fifth Amendment and declined to answer questions before Congress on Nov. 14.
It's not clear how the fungus got in the steroid vials, but an FDA investigation revealed that a quarter of the steroid vials in an NECC bin contained "greenish black foreign matter," according to an FDA form released on Oct. 26. The form went on to identify several clean rooms -- where sterile products are produced -- that had either mold or bacterial overgrowths.
The longest fungal infection incubation period the CDC recorded to date was 120 days, Chiller said. However, the longest incubation period from a previous fungal meningitis outbreak was 152 days.
"We hope that's the exception, not the rule," Chiller said. "We hope we're nearing the end of this."
In all, 590 people in 19 states have become ill with meningitis or another infection as a result of the tainted steroid injections manufactured by the New England Compounding Company. Of those, 368 were fungal meningitis and 192 were spinal infections without meningitis. Other ailment categories included strokes and joint infections.
Perplexingly, the fungal meningitis case tally reached 475 cases on Nov. 19, but some cases have been reclassified as spinal infections, Chiller said. The CDC started dividing meningitis cases into meningitis cases and spinal infections only on Nov. 26, causing the meningitis count to drop to 360 (including secondary spinal infections) and the spinal infection count to begin at 128 that day.
Copyright 2012 ABC News Radio