Roughly 13,500 people from the Ebola-stricken countries of Sierra Leon, Guinea and Liberia have visas to visit the United States, according to federal data.

The data doesn’t show how many of those people are already in the United States, but visitors from those countries should be excluded until they can show they’re free of Ebola, said Jessica Vaughan, policy director at the Center for Immigration Studies, a group that pushes for low-scale immigration.

“It would be reasonable [for the president] to designate Ebola as a communicable disease of public health significance. That would enable the State Department to impose tighter restrictions on visitors” from countries with Ebola outbreaks, she said.

Under current policies, only people with obvious Ebola symptoms are excluded by border officials. But a person can be infected with the disease, and not show any symptoms, for up to 21 days.

On Sept. 30, federal officials announced that a Liberian had flown into the United States on Sept. 20, and had began to show obvious symptoms of the disease on the 24th. Disease-carriers can transmit the disease once they have symptoms.

The Liberian is now being treated in a Dallas hospital, and federal officials are trying to contact everyone who was in contact with the Liberian. For example, several medical professionals have been kept under watch after briefly treating the Liberian on the 24th.

Without the visa changes, the federal government is encouraging foreign government officials, professionals and wealthy people to flee Ebola countries to get free medical services in Texas and other states, she said.

“People are already coming here for ‘birth tourism'” to ensure their children has U.S. citizenship, Vaughan said.

“There’s no reason that people won’t come here for treatment that doesn’t exist in their country,” she said, especially “if there is no effort to recoup [medical] costs or to prevent people coming.”

“People pay attention to our border policy and try to take advantage of anything they see,” she said, citing the surge of 130,000 poor Central Americans who have crossed the southern border since last October.

President Barack Obama has the authority to limit visits from diseased countries, she said.

Namibia, Kenya and Zambia have already barred or restricted travelers from the three Ebola countries.

In contrast, “where immigration and travel security matters are concerned, this [U.S.] administration has a history of trying to sweep potential security and health threats under the rug,” said Vaughan. “They’re on the side of acting like there not a threat, there’s nothing to see here,” she said.

The United States is already spending at least $750 million, and deploying roughly 3,000 U.S. troops to the region, to suppress the disease in the three countries.

Vaughan’s estimate of 13,500 outstanding visas includes visas for people that have already arrived, and people that have arrived and let. The federal data does not show how many visas remain unused.

The State Department has also granted visas to 195,000 Nigerians. That’s important, because Nigeria is very close to the infected countries. However, Nigerian officials and Western aid workers have blocked one Ebola outbreak in Nigeria, which infected 19 people.

The State Department’s website shows how many visas have been awarded to people in various countries. The total numbers have to be reduced because visas typical expire after one year or two years.

Section 212(a) of the Immigration and Naturalization Act allows the federal government to exclude visitors who may be carrying diseases.

Visitors with “a physical or mental disorder and behavior associated with the disorder that may pose, or has posed, a threat to the property, safety, or welfare of the alien or others … is inadmissible,” says the law.

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