Updated

The U.S. House Committee on Energy and Commerce has requested briefings this week by representatives of the Food and Drug Administration and Centers for Disease Control and Prevention on the deadly meningitis outbreak, which has claimed at least 12 lives and sickened more than 120 in 10 states.

This rare form of meningitis is not transmissible from person to person. State and federal health officials have traced it to two types of fungi that apparently contaminated an injectable steroid used for treating lower back pain.

Related: Meningitis outbreak death toll rises

The medication, methylprednisolone acetate, was formulated by the New England Compounding Center (NECC), a specialty pharmacy in Framingham, Mass.

In a separate letter to the FDA, Rep. Edward Markey (D-Mass), who serves on the committee and represents the district where NECC is located, expressed concern that pharmacies compounding drugs into specialized formulations face less regulatory oversight than the actual drug manufacturers.

"Compounding pharmacies fall into a regulatory black hole," Markey wrote. "State regulators have primary oversight responsibility over these pharmacies, however, limited state resources and varying standards and regulatory requirements affect the adequacy of state regulation."

Although federal health officials have traced the fungal contamination to NECC, the FDA is still investigating how the fungi got into the medication. Initially, they identified the contamination as the fungus Aspergillus.

Yesterday, Tennessee health officials announced they had identified a second fungus called Exserohilum as the primary source of meningitis cases in their state associated with contaminated back pain injections.

Although NECC recalled the suspect medication on Sept. 26, state and federal health officials continue to tally new cases of fungal meningitis.

Today, the Florida Department of Health confirmed that state's first fatality associated with the outbreak. The case involved a 70-year-old man who died from fungal meningitis in July, a month before health officials discovered the tainted medication.

But public health officials also expect to see new cases emerge because of the disease's long incubation period.

Typically, infected persons display symptoms one to four weeks after exposure. However, Tennessee health officials said they've seen incubation periods ranging from six to 42 days. And some experts believe there may be rare cases where patients show no symptoms for several months.

"The period of risk is ongoing, but the period of exposure is over," said Dr. John Dreyzehner, commissioner of the Tennessee Department of Health.

Public health officials are urging people who received shots of the medication in question to call a physician if they display any unusual symptoms. Fungal meningitis can cause conditions ranging from flu-like symptoms, such as fever and headache – to neurological problems, such as numbness and confusion.

According to Dreyzehner, anti-fungal medications appear to provide an effective treatment for victims of this outbreak. Public health officials believe identifying and treating patients early will produce the best outcomes.