Ebola has surfaced in Uganda, forcing the country to lockdown two districts to reduce the risk of virus spread. The question is, can it reach the United States?
Ebola is considered highly contagious under specific conditions, and most troubling, carries with it a high level of fatality. Around one-half of the people who become infected do not survive. Even those who survive must endure a plethora of debilitating symptoms, including fever, severe headache, muscle pain, weakness, fatigue, diarrhea, vomiting, stomach pain and bleeding.
Our world has shrunk, with global air travel connecting everyone around the globe within 24 hours. This means that an infection in Africa can become an infection in Europe, Asia, and the Americas in very short order. A possible new case of Ebola reported in Israel highlights how easily it can move across the globe.
The United States is conducting Ebola screening at five international airports, with around 140 people entering the United States from Uganda every day. The problem is that if a person is found to have Ebola, they have exposed other travelers on the plane. Tracking such people and asking them to isolate and quarantine will be challenging.
Ebola is not airborne, hence cannot be transmitted through the air like COVID-19. People most at risk on an airplane are the passengers sitting directly adjacent to an infected traveler.
There is a recently approved Ebola vaccine, although it is effective only against a particular species, not the Sudan species circulating in Uganda.
The ideal testing should be done at both point-of-departure and point-of-arrival. The earlier in the travel process one detects an infection, the less risk of transmission. Much like airport security, it is not conducted after an airplane has landed, but rather, before takeoff. The Centers for Disease Control and Prevention (CDC) deployed 27 people to Uganda to support surveillance and containment efforts, which can lay the groundwork for targeted point-of-departure testing for at-risk travelers.
So, should the United States, and other countries, be concerned? Is this a viral threat whose risk is being blown out of proportion to reality? The data provide information to answer these questions.
Since Sept. 20, Uganda has 90 confirmed and probable Ebola cases in a country of 45 million. Of these people, at least 44 have died, resulting in a 50 percent case fatality rate. The actual number of cases may be even higher. By comparison, the case fatality rate for COVID-19 is just over 1 percent.
When a virus carries with it a high fatality rate, the population risk calculus makes the bar for aggressive preventive action that much lower. At the extreme, if a disease has a 100 percent case fatality rate, then full prevention is critical, since everyone who would become infected would be guaranteed to die. With a fatality rate of 50 percent or more, similar precautions are needed.
Another issue is risk to health care staff. Four of the deaths in Uganda were health care workers. In any setting, protection of health care workers providing care for Ebola infected patients is a top priority.
It is conceivable that some health care workers may be reluctant or unwilling to care for Ebola patients, given the personal risk. Health care systems already stretched thin from the COVID-19 pandemic can ill afford to lose more staff.
Given the high fatality rate, Ebola infections incite fear. Currently, Ebola does not pose an immediate threat to the United States. Yet, the best time to address any potential threat is before it becomes unmanageable.
Continued support for Uganda to conduct surveillance, containment and treatment efforts, as well as targeted at-risk point-of-departure and point-of-arrival screening provide the most sensible actions at this time.
Sheldon H. Jacobson, Ph.D., is a professor in computer science at the Carle Illinois College of Medicine at the University of Illinois Urbana-Champaign. A data scientist, he applies his expertise in data-driven risk-based decision-making to evaluate and inform public policy.
Janet A. Jokela, MD, MPH, is the executive associate dean in the Carle Illinois College of Medicine at the University of Illinois Urbana-Champaign. She is an infectious disease and public health physician.