U.S. health officials are preparing to screen passengers flying in from Rwanda for symptoms of Marburg virus, a serious infection similar to Ebola.

“Starting in mid-October, air passengers who have been in Rwanda in the past 21 days will have their travel to the United States rerouted” to one of three airports: Chicago O’Hare, JFK in New York and Washington Dulles in suburban Virginia. The Centers for Disease Control and Prevention said in a statement on Monday.

According to the statement, passengers landing at one of these airports will be required to meet with CDC staff to check their temperature and assess other visible symptoms such as a sore throat, vomiting or rashes that often appear on the upper body.

According to the CDC, people infected with the virus may begin showing symptoms two to 21 days after exposure.

Screenings are scheduled to begin the week of October 14th.

Marburg is a virus that causes hemorrhagic fever and internal bleeding, similar to Ebola. Like Ebola, it spreads through contact with bodily fluids, including blood and semen. There is no treatment or vaccination.

No Marburg cases have been detected in the United States. Rwandan health officials had reported 49 cases as of Sunday, according to the U.S. Department of Health and Human Services.

At least twelve, almost a quarter, have died. According to the World Health Organization, the mortality rate can be as high as 88%.

Nineteen cases occurred among healthcare workers.

The CDC began warning U.S. doctors about Marburg last year. The risk to the population is low, it said.

Also on Monday, the CDC issued a so-called Level 3 travel health advisory warning people against non-essential travel to Rwanda.

The advisory recommended that anyone who needs to travel to the outbreak area monitor for symptoms for 21 days.

“If you experience fever, chills, headache, muscle pain, rash, chest pain, sore throat, nausea, vomiting, diarrhea, or unexplained bleeding or bruising,” the advisory says, “isolate immediately and seek medical attention.”