The Biden administration is racing to expand the number of U.S. labs that are able to test for the virus behind a swelling Ebola outbreak in Uganda, as health officials prepare for what they say remains an unlikely but real possibility that the virus could enter the country.

Most of the tests that were rolled out around the U.S. during a previous Ebola scare in 2014, which involved a strain known as Zaire Ebolavirus, were never authorized by the Food and Drug Administration to be used for diagnosing the Sudan strain, which is behind the current surge in Uganda.

“CDC has been very active on the domestic preparedness front and addressing exactly this issue of the lab testing has been a huge priority,” the Centers for Disease Control and Prevention’s Mary Choi told a session at the ID Week conference last week.

A few weeks ago, only eight members of the publicly-funded Laboratory Response Network had the ability to test for the virus, Choi said.

That number has now risen to 22 labs across the network, a CDC spokesperson said Tuesday.

More than a hundred cases of the often deadly virus have been confirmed or suspected in Uganda, according to a tally by the CDC. Cases have been spotted in the nation’s capital city Kampala, which raises concerns about wider spread. More than two dozen deaths have been reported since the outbreak began in September.

After an incubation period of up to three weeks, early Ebola symptoms — like fever and fatigue — can be difficult to distinguish from other infections. The disease then escalates to more dangerous symptoms, including severe diarrhea, bleeding and vomiting. Between 41% and 100% of reported cases in previous outbreaks of Sudan Ebolavirus have died, the World Health Organization estimates. 

There is a vaccine that targets Zaire Ebolavirus, but it is not expected to work against the current strain. Some promising new vaccine candidates are expected to be deployed soon in Uganda in hopes of curbing the outbreak. 

Travelers entering the U.S. after having spent time in outbreak-affected areas in Uganda are being screened by authorities at five airports around the country for symptoms, under a program to funnel travelers that was restarted a month ago.

They are then followed up by local health officials for at least three weeks after arriving at their destination, under guidance published earlier this month by the CDC. 

Unlike Zaire Ebolavirus, there are no rapid test kits available to spot infections by Sudan Ebolavirus. Doctors must draw blood samples from patients suspected to have the virus, which are sent off to labs that can test for the strain.

Those test tubes can then be run through systems like the so-called “Warrior Panel” developed by the firm BioFire Defense. 

“There is a lot of cross collaboration between agencies and CDC to make this happen,” Choi said, pointing to efforts like sending loaner BioFire systems to testing facilities and having weekly calls to help them ramp up.

Earlier this month, the Administration for Strategic Preparedness and Response announced it would fund accelerating clearance of BioFire’s test by the FDA, which could allow more labs to use the system.

“A select number of labs dispersed throughout the US are able to test, but we aren’t able to say the exact number. CDC is also working to bring on additional labs,” Chris Mangal, director of preparedness and response for the Association of Public Health Labs, said in a statement.

The screening test itself takes around “an hour or so to run,” Mangal said. That does not account for the time it takes to process and confirm the samples by the CDC.

“At this point the most important thing is that we have a test and several labs around the nation that are able to test,” Mangal said.

Preparing for potential cases

The federal push to scale up U.S. testing capacity for Sudan Ebolavirus comes as authorities have been bracing for the “low” risk that an infected traveler could bring it into the country from Uganda.

“While they are working as quickly as they can to increase the number of laboratories that are able to test, as of today, that number is still very limited,” the University of Nebraska Medical Center’s Vicki Herrera said at a town hall on October 21. 

Herrera was speaking at a webinar hosted by the federally-funded National Emerging Special Pathogens Training & Education Center for frontline health care workers preparing to field potential Ebola patients.

“The best thing that you can do is to contact your local public health departments and they can help you determine what testing is available and where,” said Herrera.

The U.S. has awarded federal dollars to support a network of “regional treatment centers” prepared to isolate and treat patients with “special pathogens” like Ebola. 

On Monday, the Biden administration announced it had awarded an additional $21 million to the hospitals and was adding a handful of new facilities to the nation’s “National Special Pathogen System.”

However, the responsibility for initially handling Ebola patients — at the airports or around the country — would likely fall first to a local hospital outside of this network.

For example, in New Jersey, officials in Essex County said that University Hospital in Newark will be tasked with responding to potential cases, if they are identified at nearby Newark Liberty International Airport.

James Moss, state hospital coordinator for the Virginia Department of Health, said in an email that hospitals in the counties around the state’s Dulles International Airport were rotating duties for handling potential cases from the CDC’s quarantine station at the airport.

“I will say that, in terms of Uganda and the risk right now, it is different than in West Africa,” Choi said, comparing it to the region where the 2014 outbreak was centered. “In West Africa, it was three large countries. The outbreak affected travel hubs. It had affected the capital. And we had a lot of travelers coming because you have three countries, right? So you had potentially a lot of travelers coming through.”

The U.S. is currently averaging about 140 passengers a day funneled to the five airports for evaluation, the CDC spokesperson said.

“That’s pretty low compared to what it was in West Africa. But despite that, I do think that CDC and other agencies have been very forward leaning on that,” added Choi.