Authorities and vacationers in Myrtle Beach, South Carolina, are waiting anxiously for more information on a case of flesh-eating bacteria that struck a Lumberton, North Carolina, grandmother who had been staying in the area last week.

Family of the woman, Bonita Fetterman, stated matter of factly online and to local media that she contracted the dire bacterial infection from waters at the beach. But authorities there are skeptical, given frequent water testing they conduct. They’re pressing for more information.

The case came to light following a viral Facebook post Sunday by Fetterman’s daughter, Marsha Barnes Beal. In the post, Beal reported that her mother was in stable condition at University of North Carolina Medical Center in Chapel Hill after being airlifted and admitted to the intensive care unit there. Asking for prayers, Beal said doctors were preparing to cut away the infected flesh from her leg to try to salvage the limb.

Along with the post was a gruesome picture of Fetterman’s neon pink, blistering leg (.jpg, you've been warned) and a claim of the infection's origin: the waters of Myrtle Beach. The post went viral. As of Wednesday morning, it has been shared more than 93,000 times.

Speaking with NBC-affiliate WMBF, Fetterman’s granddaughter gave a more detailed account. She said that during their trip to the beach last week, Fetterman cut her leg on a chair on their hotel’s balcony. Fetterman considered it a minor cut and didn’t seek medical attention. She later went down to the beach. On the family’s way home on Saturday, Fetterman noticed blistering on her leg. By the evening her leg had turned purple and her family took her to the hospital. The infection continued to spread. Facing amputation and a possible fatal situation, Fetterman was transferred to UNC Sunday.

According to the Centers for Disease Control and Prevention, necrotizing fasciitis—aka flesh-eating infections—are those in which bacteria ravage and kill soft tissue, often using toxins. The fast-moving infections can be caused by any of several types of necrotizing bacteria, including A Streptococcus (group A strep), Klebsiella, Clostridium, Escherichia coli, Staphylococcus aureus, and Aeromonas hydrophila. Since 2010, there are about 700 to 1,100 reported cases in the US each year. Though it’s likely that not all cases are reported, case counts don’t appear to be on the rise.

An infection can ignite when one of those bacteria enter a wound, such as Fetterman’s cut. Those most at risk of having wounds infected with necrotizing bacteria are people with diabetes, kidney disease, cancer, or other chronic conditions. In terms of exposure risks, the CDC notes water as a source, including in whirlpools, hot tubs, swimming pools, and natural bodies of water, such as beaches. But, the agency notes, most cases occur randomly.

“It’s important to note that this type of condition is not necessarily associated with exposure to natural waters like oceans, lakes or rivers or poor water quality,” South Carolina Department of Health and Environmental Control spokesperson Robert Yanity told myrtlebeachonline.com.

In a statement, the City of Myrtle Beach responded to the situation, writing:

The City of Myrtle Beach is aware of a Facebook post that claims bacterial issues along the Grand Strand. We have had no reports and no direct contact about any such issues. The city has been unable to confirm the location or date of any such incident. At this point, all we have is a Facebook post, with no confirmation. Our ocean water quality is tested twice weekly, with excellent results. If we can determine where such contact may have occurred, we can order additional water quality tests to determine whether any connection exists.

City spokesperson Mark Kruea told The Washington Post that the city had reached out to Fetterman’s family but had not received a response.

“We don’t think the water is a factor,” he added. “But in the absence of additional information I’m not sure what to do at this point.”