The biggest city in the United States got its first confirmed case of Ebola tonight, after Dr. Craig Spencer came down with a high fever nine days after returning from treating the outbreak in Guinea and tested positive for the virus.
Attention quickly focused on Spencer’s activities before the virus was diagnosed—specifically his travels on New York City’s sprawling subway system, his visit to a Brooklyn bowling alley, and his use of an Uber taxi.
Three people who were in contact with Spencer have been quarantined as a precaution. But public health experts in New York and elsewhere are unanimous that the risk to the broader public—subway riders and bowlers alike—is extremely low. Here’s why:
Ebola is only contagious when it’s symptomatic
This is probably the most important thing to keep in mind. As Quartz has reported, people cannot transmit Ebola unless they are running a fever. Spencer was carefully monitoring his temperature twice a day for the tell-tale symptom of the virus, as health protocols suggest, since he returned from West Africa.
And this is key: Public health officials said at a press conference this evening that Spencer had no fever on the evening of Wednesday, Oct. 22, when he went bowling, took the A and L lines of the New York City subway, and used an Uber car.
“When the doctor was on the subway, he had no fever, no diarrhea, no vomiting, no blood loss, which are symptoms that occur when people are much sicker,” said New York City health commissioner Mary Travis Bassett, “and so he did not have a stage of disease that creates a risk of contagiousness on the subway.”
“We consider that it’s extremely unlikely—the probability being close to nil—that there would be any problem related to his taking the subway system,” she added.
Even when Ebola is contagious, it’s very hard to transmit
Unlike the influenza virus, which is probably going to kill several thousand people in the US this year, Ebola is not airborne—that means you can’t catch it when somebody coughs or sneezes.
And even a symptomatic Ebola patient with a high fever would be unlikely to transmit the virus simply by touching a door or subway pole. That’s because the virus is primarily present in high levels in blood, feces, and vomit. By the time it builds up to a potentially infectious dose in saliva or urine, patients are usually close to death, and would probably be unconscious—and almost certainly unable to ride the subway.
Another way to look at this issue is to examine the case of Thomas Eric Duncan, the Liberian Ebola patient who died in Dallas, Texas earlier this month. Dozens of people had contact with Duncan—including his wife, who slept in the same bed with him—but the only people infected by him were two nurses, who presumably had close contact with his blood, feces, and vomit while treating him in the later stages of the disease.
As the New York Times Well columnist Donald McNeir (paywall) noted:
Africa is full of overcrowded public transport — buses, minivans and some trains. There are no known instances of transmission in those environments. On July 20, a dying Liberian-American flew to Nigeria and was vomiting on the plane. All 200 people aboard were monitored; none fell ill.
And as one of Spencer’s Harlem neighbors told the New York Daily News: “I’m not concerned. I’ve had no fluid exchanges with my neighbors.”
But what about bowling balls?
Bowling alleys, with their shared shoes and balls, have long been known as a germaphobe’s worst nightmare, but like the subway they don’t pose any particular risk when it comes to Ebola. The US Centers for Disease Control has found that the hard surfaces in Ebola hospital wards—bed rails, door knobs, etc—have not been linked to virus transmission. Moreover, the “virus was not detected in any of 33 samples collected from sites that were not visibly bloody.”
McNeir of the Times—in a post succinctly titled, “Can You Get Ebola From a Bowling Ball?“—does note that “If someone left blood, vomit or feces on a bowling ball, and the next person to touch it did not even notice, and then put his fingers into his eyes, nose or mouth, it might be possible.” But if you’re finding those bodily fluids in your local alley, we’d suggest finding a new place to bowl.