Ebola is all over the news the last couple of weeks — eclipsing talk of MERS in many places. There is lots of scary reports out there, and plenty of bad information, so it’s probably worth a recap of solid, useful information.

Ebola is a virus that causes a type of hemorrhagic fever — basically it disrupts blood vessel walls and causes extensive internal bleeding. It has been around for a very long time, carried by fruit bats in very remote regions of West and Central Africa and potentially spread through infected primates. The first identified outbreak was in 1976, and there have been occasional outbreaks since then, almost always caused by someone travelling into a remote area and carrying it back to a village.

There is some disagreement about the mortality rate of Ebola; data collected from early outbreaks suggest that it may be as high as 90%, but that data is highly unreliable. More recent, better-quality data argues that the mortality rate may be closer to 55%.

The incubation period for Ebola is 2 to 21 days. Ebola is spread person-to-person through bodily fluids; it is not airborne. There is no clear evidence as to whether infected people can pass it on in the period before they show symptoms; clearly once they show symptoms they absolutely can infect others, and unfortunately in the late stages when the hemorrhaging is in full effect there is a lot of bodily fluid to be dealt with.  Of the people who recover, there is some evidence that the virus remains in their body for up to 7 more weeks and they might still be able to infect others at that time.

Because it can only spread through bodily fluids and the symptoms are so severe, past outbreaks have tended to “burn out” fairly quickly: the initially infected people get sick, a small circle of people close to them get infected before anyone realizes that it’s Ebola, and then strong measures get put in place and very few people get sick after that. This is typical of diseases with severe symptoms and high mortality rates, especially ones that are not airborne: they are simply not efficient diseases that can spread widely.

There is no vaccine for Ebola.  There is also no “cure” for it, though there is now some evidence that giving IV fluids early helps the survival rate. Also, as this article points out, there is one treatment that can be used as a last resort (to the extent it is available): serum. Serum is a time-honored approach to fighting disease: it is essentially blood components extracted from a person who has contracted and survived the disease already (and thus has antibodies in his/her bloodstream ready to fight it). The downsides of serum are that it’s difficult to make in large quantities, and it carries along with it whatever else is in that person’s bloodstream.

The reason that Ebola is in the news is that there is currently an outbreak in four African countries: Guinea, Liberia, Nigeria, and Sierra Leone. This one started in an urban area, rather than a rural, isolated one, and so it has initially spread to more people. And there is ongoing concern that it could easily be carried from those urban areas to other urban areas around the continent and the world, given the speed and efficiency of modern transportation.  The WHO is involved, monitoring the situation closely, sending teams to Africa to help with practices on the ground, and issuing regular reports.

Yesterday the WHO issued their latest report. The news, unfortunately, is not good — the number of cases continues to go up in the four countries where it has been found so far. Here’s a good, deeper analysis of the numbers on both the new cases and the mortality rate. This is all a little confusing for the people involved, because the outbreak is not showing the typical pattern for Ebola outbreaks. That may be simply the fact that this one started in an urban area and thus had more immediate vectors. We’ll know in the next few weeks.

Earlier this week, two Americans who in the region and got infected were flown back to the United States; this was all over the news because it raised the obvious question of “is it safe to bring two people infected with a contagious disease with a high mortality rate into the country?”  So let’s address that.

First, they were brought back on a direct, chartered flight, in a special airplane built out for transporting just such patients. They were then transported to special infectious disease medical units where all the proper facilities are in place to both treat them and ensure it doesn’t spread further. Plus, the hospital is in Atlanta near CDC headquarters, and at a research hospital; this will allow medical experts to move quickly forward with additional analysis of the virus and developing treatments (and perhaps a vaccine). Doing this in Atlanta is a Good Thing, because their medical facilities will not be as strained as the ones dealing with the outbreak in Africa.

Could something have gone wrong with transporting the two patients to Atlanta? Sure. But the chances were very, very small of that happening. Everyone involved are trained professionals who knew exactly what they were doing; this was not done haphazardly. It was very carefully planned and executed, knowing exactly what the risks were and the best practices for handling them.

Besides, as this article points out, the Ebola virus is already in the United States: there have been samples in infectious-disease research labs for decades. Yes, even seasoned professionals make mistakes sometimes and something could go wrong, but the upside of this practices far outweighs the miniscule risk of something going wrong.

So if you live in the United States, should you be worried about Ebola at this point?  No, unless you have travel planned to West Africa — and if you do, I’d suggest cancelling  or postponing it (the CDC does too). But for the rest of us, while there is certainly a chance that an infected person might travel to the US or some other major metropolitan area around the globe, infrastructure has been mobilized to try to avoid that and to be prepared if it does. The time to worry is if it mutates into a version that is airborne; there is no sign of that happening yet, it has never been known to happen before with any strain of Ebola, and even in the extremely unlikely case that it did, it would almost certainly become less deadly in the process (as almost always happens to viruses when they mutate into a more transmissible form).

Frankly, I’d still be more worried about MERS, and I’m not losing sleep over that either. Just keep washing your hands and practicing god hygiene. And here’s the CDC page on the Ebola outbreak, in case you want to stay up to date.

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