The 42-day risk period for contracting fungal meningitis from tainted steroid injections ended on Wednesday, since the drugs were recalled on Sept. 26, but new case reports will probably continue to trickle into the Centers for Disease Control and Prevention for at least a few months, said Dr. Tom Chiller, a fungal disease expert at the CDC
With 18 new cases reported last Friday, and abscesses causing even fungal meningitis survivors to go back to the hospital with new symptoms, sighs of relief could be premature.
"Forty-two days is not a magic number by any sense of the word," said Chiller, who is the deputy chief of the CDC's Mycotic Diseases Branch. "This is a moving target. The outbreak is evolving."
The CDC publicized the 42-day period as a way for individual physicians to determine whether putting all at-risk patients on anti-fungal medications was a good idea, Chiller said. Since anti-fungal medicine can cause liver and kidney damage, there was a risk it could do more harm than good. The long risk period would mean a long anti-fungal regimen.
A CDC analysis revealed that while preemptive anti-fungal prescriptions reduced patients' risk of death or stroke from meningitis by .1 percent, they increased the risk of other adverse health problems by up to 14 percent, Chiller said.
Chiller said this kind of fungus, exserohilum rostratum, can have a very long incubation period. Although the median incubation period so far has been 20 days, the longest incubation period went beyond 100 days, he said.
"One of the important things to add is that we do feel pretty confident that the further out you are from injection, the lower the risk," Chiller said. "When that risk becomes zero, we don't know."
So far, 409 fungal meningitis cases, including 30 deaths, have been reported to the CDC this fall. In addition, 10 people who received the shots to other parts of their bodies came down with fungal joint infections. Fungal meningitis, a deadly disease that causes inflammation of the membrane surrounding the brain and spinal column, is not spread from person to person.
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.
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 Oct. 26. The form went on to identify several clean rooms -- where sterile products are produced -- that had either mold or bacterial overgrowths.
Signs that the CDC believes new cases will taper off include the CDC's new, more relaxed online case reporting schedule. Instead of updating case counts by state every day at 2 p.m., as it had for the last month, the CDC will update Monday, Wednesday and Friday only. This Monday's steep new case count of 15 was actually only five new cases per day.
However, 18 new cases were reported between Thursday and Friday of last week, according to CDC reports. Case counts only reached 18 or higher on four days of the whole outbreak.
"All of us have our fingers crossed, and everyone acknowledges that with every day that passes, the risk diminishes," said Dr. William Schaffner, chair of preventive medicine at Vanderbilt University in Tennessee. "Although at 42 days, I'm sure people are taking a deep breath, but the reality is that they're not completely out of the woods yet."
Going forward, the CDC is encouraging people who have received the tainted shots to be vigilant about keeping track of their symptoms, and to seek medical help if necessary, Chiller said.
But even the people who got meningitis and were treated are not in the clear. The CDC has now learned that those patients are coming back with abscesses filled with fungus and pus located near the injection site.
"The new finding is that patients during treatment or reaching the end of their treatment may actually relapse and come back with new symptoms," said Schaffner, who used to be president of the National Foundation for Infectious Diseases.
Schaffner said that the abscesses, which are located just outside the spinal casing, or dura, can grow and make their way into the dura, causing a meningitis relapse.
In some patients, the abscesses are present when they receive their first meningitis diagnosis, Chiller said. In others, the abscesses form several weeks later. These pockets of infection are often treated with oral antifungal medications or surgically drained, he said.
"This has been an unprecedented event," Chiller said. "It's a new entity to us, and we're trying to engage experts in the fungal and clinical word."