The CDC published a warning on Wednesday, after an investigation found a deadly bacteria in soil and water samples in the Gulf Coast region of Mississippi. 

The investigation was initiated due to two Mississippi residents in 2020 and 2022 becoming ill and hospitalized due to melioidosis, which was believed to be caused by  bacteria in the soil near their homes.

The two US patients, who were diagnosed with melioidosis in July 2020 and May 2022, didn’t know each other but lived close to one another, according to the CDC. Both patients recovered after antibiotic therapy.

Patients who are in contact with the bacteria, by touching contaminated dirt or puddles, can develop symptoms an average of a week after they are exposed, according to the CDC.

Health authorities are urging at-risk residents of the Gulf Coast region to be cautious. 

Though the bacteria has been found previously in Puerto Rico, the CDC announcement on Wednesday marks the first time the bacteria has been discovered in the continental US.

Both of the victims of the illness, also known as Whitmore’s disease, are said to have been exposed to a strain of a rare bacteria known as Burkholderia pseudomallei, typically seen only in tropical countries.

The illness is prevalent in Thailand and northern Australia, but usually does not affect healthy people adversely. 

People with other health issues can be more susceptible. “The most common underlying conditions that make a person more likely to become sick with or die from melioidosis include diabetes, excessive alcohol use, chronic lung disease, chronic kidney disease, and immunosuppressive conditions,” according to the CDC.

The CDC said that on average, 12 cases are typically diagnosed in the US each year, in people who have traveled to a tropical country where the bacteria is found.

The disease has killed an estimated 90,000 people in the world every year.