Headache. Stiff neck. Dizziness. Fever. The symptoms could describe anyone with a range of ills, from migraine to the flu, but they're also the defining symptoms for the ongoing outbreak of rare fungal meningitis, and they're making trouble for some emergency room doctors.

Eleven people have died and 119 in 10 states are infected with the rare form of meningitis caused by contaminated pain injections, federal health officials said on Tuesday.

The Centers for Disease Control and Prevention is continuing to gather information about people who had injections of steroids into their necks or spines for back and neck pain and says as many as 13,000 people may have been given medication from a Massachusetts pharmacy, which has now closed and recalled all of its products. That makes 13,000 people who could, potentially, seek help at America's first line of health defense - the emergency room.

Fungus is not usually a cause of meningitis – usually it’s bacteria or viruses – and patients with these fungal infections are not contagious to other people.

But the fungal infection also causes more subtle symptoms than a bacterial infection and is trickier to diagnose, doctors say. CDC says some patients have had strokes. Patients who have had recent steroid injections and who have headache, dizziness, balance problems and other symptoms are being asked to contact their doctors immediately so they can be evaluated.  Some are going to their pain clinics, others to their primary care doctors, but many are relying on the emergency room.

Related story: 10 thing you need to know about the national meningitis outbreak

"About a week ago one of our pain clinics identified that about 600 people in our community were exposed to that injection," said Dr. Lee Benjamin of St. Joseph’s Mercy Hospital in Ann Arbor, Michigan. The clinic called every one of the patients, and apparently told them to visit the emergency department.

They did. "We have seen a tremendous influx of patients over the last week," Benjamin told NBCNews in a telephone interview. Benjamin estimated 50 patients were seen in his hospital's emergency department on Monday alone.

Most are appropriately worried, Benjamin stresses. "I would just remind patients that if they were exposed or they feel ill, the emergency department is always the first line and we are happy to evaluate anyone," he said. 

It just so happens that the American College of Emergency Physicians is holding its annual scientific conference this week in Denver. The outbreak has become a topic of discussion outside the regular sessions on overcrowded emergency rooms and the U.S. dependence on emergency department for first-line health care.

In this case, the CDC and state health departments have been very clear from the beginning -- the meningitis is not contagious, and people don't need to worry unless they got a spinal injection at a pain clinic that received shipments from the one pharmacy identified as the source of the contaminated drugs. Nonetheless, that's a lot of people.

"My facility has a few of the walking worried," said Dr. Ryan Stanton of Good Samaritan Hospital at the University of Kentucky in Lexington. "We were just starting to get inundated with flu cases," Stanton said. "Just about everybody has got headache, symptoms like that."

News stories can sometimes send people flooding ERs, said Dr. Jose Torradas of North Shore University Hospital in Manhasset, New York. "In my hospital, you will see a news story, and within a day there will be an increase," Torradas said. "The ED volumes increase, time pressures, and other issues become very real when stories like these break."

This can strain any ER and sometimes the whole hospital, Benjamin said.

Each patient needs to be interviewed carefully. If someone had a recent steroid injection -- in this case, dating back to May -- if he or she has symptoms, then they have to undergo a procedure called a lumbar puncture to look for signs of meningitis. It's painful, but can show inflammation immediately. "The recommendation is to start treating them," said Dr. James Williams of St. Joseph's Medical Center in Baltimore. 

Patients likely will get antifungal drugs but also antibiotics just in case their meningitis is the highly dangerous, bacterial kind, said Benjamin. It can take a few days to culture a specimen of spinal fluid and confirm that a fungus is causing the infection. The CDC says two different types of fungus, Exserohilum and Aspergillus, have been taken from patients in the current outbreak.

Williams says patients who believe they have may have been injected with the contaminated steroids should not worry about bothering busy emergency departments. "Please don’t be worried about crowding. People think ERs are overcrowded but it’s not true. Particularly in this case, you need to be seen immediately."

Related stories:

Eleven dead in fungal meningitis outbreak

One patient's fungal meningitis fears

More than 13,000 may have received posiibly contaminated drugs