U.S. health officials now estimate that around 14,000 Americans may have been exposed to recalled steroid injections that have been linked to an outbreak of fungal meningitis.

The U.S. Centers for Disease Control has also confirmed that the fungus Exserohilum rostratum was present in 10 people stricken with the infection. A Tennessee patient, the first case identified in the outbreak, was infected with a different fungus called Aspergillus.

As of Thursday, the toll of the fungal meningitis outbreak stands at 169 cases across 11 states, with 14 deaths. Officials have also found the first possible meningitis case resulting from a joint injection with the implicated steroid medication, though final lab results have still not come in. All other patients thus far received injections in the spine.

The medication implicated in the outbreak is three lots of preservative-free methylprednisolone acetate made by and distributed from a New England Compounding Pharmacy Inc. facility in Framingham, Mass. On Oct. 6, NECC recalled all products made at and distributed from the Framingham branch that are currently in circulation.

Health officials have thus far found fungal contamination in 50 vials of drugs from NECC, Deborah Autor, the FDA deputy commissioner for global regulatory operations and policy, told reporters on a conference call.

People that received the potentially contaminated medication should seek immediate medical attention if they exhibit any of the symptoms of fungal meningitis: worsening headache, fever, sensitivity to light, stiff neck, weakness or numbness, or slurred speech. Even a minor headache could be a sign of trouble -- some already documented victims in the outbreak have complained of only slight headaches at first.

Symptoms typically set in between one and four weeks after the injection, but longer incubation periods are not unheard of.

The CDC is recommending that doctors treat patients with confirmed fungal meningitis with two antifungal drugs: voriconazole and liposomal amphotericin B.

NECC is a compounding pharmacy that makes custom versions of medicines. It has been previously investigated by Massachusetts health regulators and the U.S. Food and Drug Administration, and the FDA sent the company a warning letter in 2006 about alleged violations, including one involving the injectable cancer drug Avastin.