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Federal and state health officials are racing against the clock to track down as many as 13,000 people who may have received tainted back-pain injection suspected in a fatal outbreak of fungal meningitis.

The U.S. Centers for Disease Control  said state health departments are working closely with clinics to contact the patients “through letters, emails, phone calls – you name it.”

At least 119 people have been sickened with meningitis and/or strokes, and 11 of those have died, according to the CDC. Current numbers do not reflect patients who may have received the shots for pain unrelated to the back – for example, some patients may have received shots due to neck, knee and shoulder pain.

Six of those deaths have occurred in Tennessee.

Patients who received a tainted steroid injection between July and September 28 – and haven’t experienced symptoms yet – may not necessarily be in the clear just yet, according to Tom Skinner, a spokesperson for the U.S. Centers for Disease Control.

"A New England Journal of Medicine article in 1993 stated the incubation is four to 10 weeks, but other sources cite two weeks to even 11 months – although this is very rare."

— Dr. Nadya Swedan, NYC physiatrist

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“Based on our experience with cases so far, the incubation period is about one to four weeks,” Skinner said. “But we don’t have a lot of experience with this organism being transmitted in this manner – so we can’t be absolute. If someone got a shot four weeks ago from one of those clinics that received the tainted steroid – they are not out of the woods. That person should talk with their doctor and be monitored over an extended period of time.”

Dr. Nadya Swedan, a physiatrist based in New York City, often uses steroid injections – which are different than epidurals –  to treat her patients. Although she does not purchase her medicine from the New England Compounding Center in Framingham in Massachusetts – she said the incubation period could be anywhere from two to 10 weeks.

Swedan said the incubation period for the most common type of fungal meningitis – cryptoccocus, which is most likely caused from exposure to pigeon droppings – isn’t even known for sure.

“A New England Journal of Medicine article in 1993 stated the incubation is four to 10 weeks, but other sources cite two weeks to even 11 months – although this is very rare,” Swedan said.

Previously, the CDC said the incubation period could last “weeks to months” in rare instances.

Knocking on doors

In Ohio, health officials said Monday they are mobilizing community resources, including sheriff's offices, to check on patients who have received the injections.

"If that means knocking on doors, then that's what they will do," said Beth Bickford, executive director at the Association of Ohio Health Commissioners, in a statement Monday. The state has so far reported one case of fungal meningitis likely caused by a tainted epidural steroid injection.

About 17,700 single-dose vials of the steroid have been sent to 23 states and have since been recalled by the NECC.  Tennessee has reported the most cases, but other affected states include Michigan, Virginia, Florida, Minnesota, North Carolina and Ohio. A list of all the affected clinics is on the CDC’s website.

Each state is handling how to contact patients in a different manner.

For example, in Florida, Pain Consultants of West Florida was in the process of tracking down patients who had the injection, but over the weekend, the county health department took over.

“We attempted to contact patients several times by phone,” said Dr. John Lanza, director of the Escambia County Health Department in Pensacola, Florida. “If we can’t get them, we break it down by county.”

Lanza said the next step would be to send staff out to individual addresses to talk to patients in person, or at least drop off a letter.

In Virginia, Imaging Roanoke said in a statement is has called all patients individually, and it continues to work with state and federal officials. The facility would not comment further, citing privacy concerns.

'Not FDA-approved'

The compounding center, which has been the focal point of previous complaints and investigations, recalled the drug – and everything else it makes – over the weekend.

"While there is no indication at this time of any contamination in other NECC products, this recall is being taken as a precautionary measure," the company said in a statement.

Health inspectors found at least one sealed vial contaminated with fungus, and tests are being done on other vials.

According to Dr. Shaheda Quraishi, a attending physiatrist at North Shore-LIJ Cushing Neuroscience Institute in New York, compounding pharmacies are held to similar standards as pharmaceutical manufacturing companies; however, they are not regulated by the Food and Drug Administration.

"For example, the state of Massachusetts has jurisdiction over the compounding pharmacies, regular pharmacies and physicians in Massachusetts," she added.

Swedan said compounding pharmacies may be attractive to some doctors because they are cheaper – but she prefers to use FDA-approved drug companies.

"Some patients and doctors believe medications should be 'preservative-free,' and that is why they use compounded pharmacies," she said, noting the compounding pharmacies are not FDA-approved.

Meningitis is an inflammation of the lining of the brain and spinal cord, and a back injection would put any contaminant in more direct contact with that lining.

Symptoms on meningitis include severe headache, nausea, dizziness and fever. The CDC said many of the cases have been mild, and some people had strokes.

The Associated Press and Reuters contributed to this. 

Additional reporting by Alex Crees and Loren Grush.