The five patients in three different counties were hospitalized after becoming infected in July or August while exposed to salt or brackish water during activities such as swimming, crabbing, and boating, the state health department said in a news release Saturday.

“This suggests the Vibrio bacteria may be present in salt or brackish water in or near Long Island Sound, and people should take precautions.”.

Vibrio vulnificus infection is rare, with Connecticut having reports of only seven cases in the 10 years from 2010 through 2019, the health department reported.

It can occur when open wounds are exposed to warm salt or brackish water, which is a mix of salt and fresh water, and can lead to serious illness requiring intensive care or amputation of a limb.

And, in the study, a team of infectious disease specialists at Cooper University Health Care in Camden, New Jersey, describe five cases of Vibrio vulnificus necrotizing fasciitis that occurred during 2017 and 2018.

Katherine Doktor, an infectious disease specialist at Cooper University Health Care, said in a statement to NBC News at the time