Ebola seems to be making new headlines every day. There is enormous interest in the fight against the disease in West Africa,as well as in the possibility of its spreading to other continents. The U.S. Centers for Disease Control and Prevention (CDC) has estimated there could be between 500,000 and 1.4 million Ebola cases, mainly in West Africa, by January 2015.
There is, of course, significant uncertainty in these numbers. The risk of widespread and sustained transmission over multiple continents, as is typical during a pandemic, is currently considered to be low. Yet, there are many factors that could influence this probability.
In my next post, I'll consider three factors, or events, that could reduce the risk of an Ebola pandemic. But I'll start herewith a discussion of three key factors that could increase it:
Gaps in Ebola preparedness and response are not rectified in countries with presumably robust healthcare infrastructure
First responders and healthcare workers should receive adequate personal protective equipment (PPE) and training in protocols, such as what to do if a suspected Ebola case arrives at their healthcare facility, and how to care for an Ebola patient without infecting themselves or others.
Every hospital or clinic that sees patients should have a response protocol, which should be rehearsed and drilled so that all staff are comfortable with what would be required if a case presents in their healthcare setting.
Although recent events (in Madrid and Dallas) have demonstrated some shortcomings in response, it is likely that the response going forward can and will be improved with swift and concerted action. Just last week, more than 5,000 healthcare workers in New York City received training, including hands-on demonstrations of the correct use of PPE; while this is a good start, more must be done to improve preparedness.
Ebola is imported into additional areas lacking robust healthcare infrastructure
Right now this seems to be the most likely and immediate potential threat. An infected or exposed person could travel from the outbreak zone to other countries in Africa or Asia that may not be able to mount a swift containment response. An imported case was identified in Mali, a country neighboring Guinea, last week. The world will be watching closely to see if containment efforts are successful there.
If the outbreak reaches Asia, many parts of Asia are much better connected with the rest of the world (by way of air travel) than Africa, making traveler screening even less logistically feasible, and increasing the potential for further international spread. Countries with robust healthcare infrastructure could still respond to imported cases, but there could be a larger influx of them.
The Ebola virus mutates to spread more easily
This could happen if the virus were to develop the ability to spread via small airborne droplets, and/or it starts to be able to spread before symptoms appear. Some researchers have stated that, if transmissibility increases, severity of illness would likely decrease. While this is often true for diseases that require direct contact, it is not necessarily true for all diseases. One notable example is cholera; since it is spread via a waterborne route, the mortality of the host is not a great impediment to transmission. Scientists generally believe the probability of the Ebola virus mutating to spread via a new transmission route is extremely low.
A couple of reasons for this are that Ebola virus is not particularly hardy in the environment and because a significant number of changes to the virus would be required to latch onto respiratory cells in a way that would allow airborne spread to occur. However, while the probability is low, it is not zero.
While these points are sobering, we also have within our power the potential to decrease the overall global pandemic risk from this Ebola outbreak. Again, my next post will outline three key factors that could help us do so.
For more information, see our recent AIR Currents article.