Thomas Eric Duncan, who contracted Ebola in the U.S. after visiting Liberia earlier this month, came in contact with as many as 80 people, according to Texas health officials, NBC News confirms. These people came into contact with either Duncan or his family. Though they were not in close contact, Dallas county health and human services director Zachary Thompson says, they did have some kind of contact with or exposure to the patient.

Four family members who had contact with Duncan were ordered this week by Texas health officials to stay home until at least Oct. 19, when the incubation period has passed, to prevent the possible spread of the virus. Until now, the only known cases of Ebola in the U.S. involved American doctors and aid workers who were infected while overseas and returned to the country for treatment.

Duncan left Liberia on Sept. 19 and arrived in Dallas, Texas the following day to visit relatives. He became sick with symptoms days later.

Duncan is being treated in intensive care at Texas Health Presbyterian Hospital Dallas, according to Edward Goodman, the hospital’s epidemiologist. The ambulance he arrived in was later decontaminated, a Dallas official confirmed, and two paramedics and one paramedic intern are being monitored after transporting the patient to the hospital.

There have been more than 6,500 reported cases of Ebola in Guinea, Liberia and Sierra Leone as of Tuesday, and it has caused more than 3,000 deaths, according to the World Health Organization.