WASHINGTON/BOSTON (Reuters) - The death toll from a meningitis outbreak linked to contaminated steroids jumped to 19 on Wednesday, while U.S. lawmakers pressed federal health regulators to explain what they knew about the pharmacy that produced the drugs.

The Centers for Disease Control and Prevention said four more deaths had been confirmed in the last 24 hours, including two in Tennessee, the state hardest hit with eight deaths since the infections were discovered in late September.

Virginia and Florida each reported one new death.

The number of new cases of fungal meningitis linked to steroid injections from the New England Compounding Center rose by 14 to 245, the CDC said in its latest daily update. Two additional infections have not been confirmed as meningitis.

The daily tally was a reminder that one of the worst U.S. health scares in recent years has not been contained, despite emergency steps to recall the medications and stop the use of products from New England Compounding Center of Massachusetts.

NECC has recalled all of its medications and health authorities are warning patients who may have been treated with the drugs to watch for symptoms. Special agents from the U.S. Food and Drug Administration raided NECC's Framingham facility near Boston late on Tuesday as calls in Congress grew for a criminal investigation.

The FDA is also under scrutiny. While it has limited authority to regulate pharmacies like NECC, it had flagged violations at the company as recently as 2006.

On Wednesday a U.S. House of Representatives panel investigating the outbreak gave the FDA until October 31 to turn over its documents related to NECC, including communications with state regulators and the agency's commissioner, dating back to 2004.

The panel said it heard from FDA staff last week that the agency had been assured by NECC of the pharmacy's compliance in early 2007. But the FDA representatives could not confirm whether the agency then took any steps to ensure corrective measures had been taken.

An FDA spokesman said the agency had received the letter and would respond directly to the panel.

WEIGHING THE EVIDENCE

FDA criminal investigators and federal prosecutors began sifting through evidence seized from NECC's headquarters, part of a probe that could last months.

"If the investigation finds any criminal misdoings, the Department of Justice must act decisively, file charges and prosecute the company or individuals responsible," said U.S. Representative Rosa DeLauro, a Connecticut Democrat who has proposed legislation to give FDA more authority to regulate compounding pharmacies.

A lawyer for NECC said the raid was unnecessary.

NECC is a compounding pharmacy that is authorized to prepare specific doses of approved medications, based on guidance from a doctor, to meet an individual patient's need. But evidence that it shipped large quantities of drugs throughout the United States has prompted local authorities to consider it in violation of state laws.

Meningitis is an infection of the membranes covering the brain and spinal cord. Fungal meningitis is not contagious.

The meningitis scare began last month when people began arriving at the emergency room of Saint Thomas Hospital in Nashville, Tennessee, with severe headaches and other symptoms after receiving epidural injections for back pain from a separate clinic housed in the hospital.

The injections contained the steroid methylprednisolone acetate, which was shipped by NECC to 76 medical facilities in 23 states. Health authorities have scrambled to contact nearly 14,000 patients at risk of meningitis and to remove all the products suspected of being contaminated from the shelves.

But the product was shipped as early as late May and patients continue to contact doctors with headaches, fever, nausea and stroke-like symptoms. Cases have been confirmed in 15 states, with deaths in six.

The FDA said that "out of an abundance of caution" federal and state health authorities are now trying to trace all products from NECC around the country.

A list of more than 131,000 shipping invoices for NECC products shipped to medical facilities across the United States was sent to state health authorities by the FDA earlier this week, the Tennessee Health Department said on its website.