Ebola’s arrival in U.S. was inevitable, experts say

The world suddenly seemed a lot smaller when news broke Tuesday that the first person diagnosed with Ebola in the U.S. is being isolated and treated at a Dallas hospital.
While the outbreak in West Africa has sickened more than 6,000 people and killed 3,083, it was only a matter of time before the virus hit closer to home, experts said.


Dr. Edward Goodman, hospital epidemiologist at Texas Health Presbyterian Hospital, said he was not surprised that the Ebola virus came to his doorstep, given the number of cases in Africa.
There is “plenty of opportunity for people to fly over and come to any part of the United States,” he told reporters Tuesday.


Other experts agree that it was inevitable for the Ebola virus to spread beyond Africa. Given the unprecedented scale of the virus’ outbreak in West Africa, at least a handful of imported cases were expected to arrive in other countries.
But many predicted that the Ebola virus would reach another country before the U.S. Using mathematical models to predict how infectious diseases spread, experts at Northeastern University ranked the top 15 countries where Ebola could emerge next.


The United Kingdom ranked third on that list, second only to the African nations of Ghana and Gambia. The U.S. had a much lower probability of having an imported Ebola case.
Still, Dr. Gerardo Chowell, an associate professor at Arizona State University and an expert in modeling infectious diseases, wasn’t surprised. “It’s just a matter of probabilities,” he said.

Chowell has focused on predicting the spread of the epidemic in Africa, especially Nigeria.

Rate of infection
A key factor in the spread of infectious diseases is the number of people a sick person can infect.


If that number, known as the basic reproduction number, or R0, is less than one, it’s unlikely the disease will spread. If it’s greater than one, there’s potential for a large outbreak.
In the case of Ebola, R0 has been documented to range from 1.3 to 1.8, depending on factors such as population density and how quickly cases are diagnosed and isolated.

The R0 for Ebola is a lot lower than for other illnesses such as measles, whose R0 is 18. But factors such as fear, an inadequate number of health care workers and abject poverty in parts of West Africa are fueling the spread of the virus there.
That situation is different in Dallas. “This is not Africa,” Dallas County Health and Human Services Director Zachary Thompson told reporters. “We have a great public health infrastructure to deal with this type of disease.”


The opportunity for infectious diseases like Ebola to go global has increased with international air travel — and Dallas and Houston are major hubs.

There is a direct daily flight from Lagos, Nigeria, to George Bush Intercontinental Airport in Houston. More than 71,000 people have traveled nonstop from Africa to that airport in the past year, according to the Houston Airport System. Many more passengers may have traveled to and from Africa on flights that connected in Europe and the Middle East.


There is no direct flight from a city in Africa to Dallas/Fort Worth International Airport. But D/FW saw nearly 7 million international passengers last year.
Quarantine facilities at these airports could be used to isolate travelers with symptoms of Ebola. But so far, the Centers for Disease Control and Prevention has not asked airports to adopt special measures as they did with Middle East Respiratory Syndrome earlier this year.

‘We’re prepared’
Dr. Tom Frieden, director of the CDC, and other public health officials maintain that Americans should have faith in the U.S. public health system. He told reporters that spread of the disease in Dallas is not expected because of early isolation of the patient.

President Barack Obama had met with the director at CDC headquarters in Atlanta two weeks ago.
At that time, the president offered assurances that the outbreak could be contained. “In the unlikely event that someone with Ebola does reach our shores,” he said, “we’ve taken new measures so that we’re prepared here at home.

“We’re working to help flight crews identify people who are sick and more labs across our country now have the capacity to quickly test for the virus. We’re working with hospitals to make sure that they are prepared and to ensure that our doctors, our nurses and our medical staff are trained, are ready, and are able to deal with a possible case safely.”

Posted in: