A spike in the number of cases of a mysterious polio-like illness has led to a new alert from the Centers for Disease Control and Prevention.

As of August, at least 50 people in 24 states were confirmed to have acute flaccid myelitis, a viral infection that attacks the body's nervous system and has led to paralysis and death. The federal agency posted an update earlier this week.

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In July, the Texas Department of State Health Services issued a warning to health providers after seven incidents were reported by the end of June.

There have been a total of 11 confirmed and two suspected cases of AFM in Texas to date, and five have been in Collin, Dallas, Denton and Tarrant counties, according to DSHS. The first case was reported in March, followed by two in May, four in June, three in July and one in August.

"Any time we see illnesses without an apparent explanation, it is concerning and we want to figure out what's going on," Chris Van Deusen, press officer for DSHS said on Friday. At this point, however, the agency has not seen evidence pointing to a pattern or common cause in Texas, he said.

Infection with AFM leads to the sudden onset of limb weakness and loss of muscle tone and reflexes. Other symptoms include drooping eyelids, facial weakness and slurred speech. Despite testing, health officials do not know what’s causing the uptick.

Chart showing the number of U.S. reports in 2016 of acute flaccid myelitis, a mysterious polio-like condition that affect's the body's nervous system.p (U.S. Centers for Disease Control and Prevention)

Dr. Benjamin Greenberg, a pediatric neurologist at Children's Health in Dallas has treated several cases over the past few years- including two in the past couple of months- and says symptoms tend to vary. Some patients have mild weakness in just one limb while others are unable to move their arms nor legs and are admitted to the intensive care unit.

Though more prevalent in people under the age of 21, there have been reports of AFM in adults. There is no specific treatment, but options being tested include steroid injections and the removal of plasma from the blood.

"The thing we are grappling with the most is trying to understand the scope and prevalence," explained Greenberg. While health officials in Texas have encouraged clinicians to voluntarily report AFM incidents, it is not required nationwide, which would help identify clusters.

"In a system that doesn’t have mandatory reporting, we will never know," he said. "We have concerns that cases are being missed."

This isn’t the first multi-state outbreak of the condition. Federal health officials have been investigating AFM since 2014, when a total of 120 people in 34 states were diagnosed over a five month period, including three in Texas.

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That outbreak coincided with multi-state reports of enterovirus D-68, a once-rare condition that causes mild to severe respiratory illness. It is not clear if EVD-68 is associated with the current reports of acute flaccid myelitis. The condition has been linked to other pathogens, as well as viruses such as West Nile and the one that causes polio.

The CDC says it is “intensifying efforts” to understand the cause and risk factors. Van Deusen of the DSHS said no deaths from the condition have been reported in Texas. The state urges people to take the usual precautions to avoid the spread of viruses, such as making sure vaccines are up to date, washing hands frequently with soap and water, and using mosquito repellant.