Seven people have died after contracting a rare fungal infection in connection to medical procedures in Mexico, said federal officials in a recent alert.

As of last week, seven people have died after contracting fungal meningitis after getting procedures under epidural anesthesia in Matamoros, a city in Mexico’s Tamaulipas State, the U.S. Centers for Disease Control and Prevention (CDC) said. The two clinics associated with the outbreak are River Side Surgical Center and Clinica K-3, which were closed down in mid-May.

“Anyone who had procedures under epidural anesthesia in these clinics from January 1 to May 13, 2023, is at risk for fungal meningitis,” the CDC said. The outbreak was first reported in May, leading the federal health agency to issue an alert.

Other than the seven who died, about 161 suspected cases of meningitis where there are no symptoms, 15 suspected cases with symptoms, and 10 probable cases are under investigation, said the agency. Nine cases have been confirmed so far.

The CDC urges patients who had epidural anesthesia at the River Side Surgical Center or Clinica K-3 should go to urgent care, a health center, or an emergency room as soon as possible to be tested for the fungal infection—even if no symptoms are present. Those who test positive will be asked to take anti-fungal medicines, while those who test negative will be asked to watch for symptoms of the potentially fatal infection.

“Healthcare providers should immediately report suspected fungal meningitis cases, including those possibly related to this outbreak, to their state or local health department,” the CDC also said.

Fungal meningitis cannot be spread between people. Symptoms include a stiff neck, light sensitivity, vomiting and nausea, fever, and changes in mental status.

Unlike bacterial meningitis, fungal meningitis can take weeks or longer to develop, officials say. Bacterial meningitis progresses quickly and can be fatal within days, researchers say.

According to the Mayo Clinic: “Fungal meningitis isn’t common in the United States. It may mimic acute bacterial meningitis. It’s often contracted by breathing in fungal spores that may be found in soil, decaying wood and bird droppings.”

“Fungal meningitis isn’t spread from person to person. Cryptococcal meningitis is a common fungal form of the disease,” the clinic also says. “It affects people with weakened immune systems, such as from AIDS. It can cause death if not treated with an antifungal medicine. Even with treatment, fungal meningitis may come back.”

The CDC bulletin also noted that patients who received treatment at those clinics might not show symptoms and could test positive for the infection.

“Fungal meningitis can start off mild and very quickly become a life-threatening illness. Consider printing and sharing this web page to help make sure staff and healthcare providers are aware of the situation and recommended tests,” according to the CDC, which added: “Go to the nearest emergency room as soon as possible to be evaluated for fungal meningitis, even if you do not currently have symptoms.”

Although the CDC issued its first alert weeks ago, officials still have not identified what kind of fungus species led to the infections. It’s also not exactly clear was led to the exact cause of the current outbreak.

In May, the CDC also issued a “Level 2” travel advisory after meningitis infections “have led to severe illness and death,” although it noted that fungal meningitis cases are not contagious and cannot spread to other people.

“Cancel any elective procedure that involves an epidural injection of an anesthetic in Matamoros, Mexico, until there is evidence that there is no longer a risk for infection at these clinics,” the advisory said. “Cancel any elective procedure that involves an epidural injection of an anesthetic in Matamoros, Mexico, until there is evidence that there is no longer a risk for infection at these clinics,” it also said.

The Texas Department of State Health Services similarly issued an alert last month, saying that it had identified at least five patients who were infected, according to a news release.

Matamoros remains one of the top destinations for medical tourism due to cheap and easy access, even though Tamaulipas is one of six states in Mexico where the U.S. Department of State warns Americans not to travel at all due to crime and kidnappings.

Notably, four American tourists were kidnapped in Matamoros on March 3 in broad daylight in what appeared to be a cartel shootout. Two were killed, as was a Mexican woman who happened to be nearby when the kidnappings took place. The group was traveling to Mexico so one of them could get cosmetic surgery, according to reports.

Bill Pan contributed to this report.