Ebola virus disease (EVD), formerly known as Ebola hemorrhagic fever, has been reported in humans since 1976, but the current epidemic of the disease – affecting Guinea, Liberia, and Sierra Leone – is unprecedented. There is no vaccine or cure for Ebola, and in past outbreaks up to 90% of people confirmed to have the disease died (the case-fatality rate is closer to 60% this time). A WHO fact sheet gives a grim list of the symptoms:

EVD is a severe acute viral illness often characterized by the sudden onset of fever, intense weakness, muscle pain, headache and sore throat. This is followed by vomiting, diarrhoea, rash, impaired kidney and liver function, and in some cases, both internal and external bleeding.

In this epidemic, 1,323 confirmed and suspected cases have been reported, and 729 of those individuals have died – numbers far higher than in previous outbreaks. Last month Laurie Garrett, author of The Coming Plague and Council on Foreign Relations senior fellow, explained on PBS NewsHour why this epidemic is so worrisome:

This is the first time we have ever seen an urban as well as rural Ebola outbreak. It is the first time we have seen Ebola in the capital cities. It is the first time we have seen Ebola crossing borders, now in three countries. And it is the first time we are having an Ebola experience in an area rife with the tensions and the hostilities born out of two really brutal civil wars in Sierra Leone and in Liberia, with spillover into neighboring Guinea.

So these are three small, deeply impoverished West African countries where, in the best of times, they are hard-pressed to meet the public health needs of their people and now to have what is officially designated an out-of-control epidemic on their hands.

This is a horrific disease, but it is not transmitted as easily as some other viruses. Stephan Monroe, deputy director of CDC’s National Center for Emerging Zoonotic and Infectious Diseases, explained on a July 28th CDC telebriefing, “transmission is through direct contact of bodily fluids of an infected person or exposure objects like needles that have been contaminated with infected secretions.  Individuals who are not symptomatic are not contagious.” So, as long as healthcare facilities isolate any potential cases who are showing symptoms and practice correct infection control procedures, they can control the disease’s spread.

The challenge in the affected West African countries is that patients may not all arrive at healthcare facilities, and many of the healthcare facilities where patients do show up lack the resources, such as isolation rooms and protective gear, to respond appropriately. With the affected areas not having seen Ebola outbreaks before, they are less prepared to deal with them than previously affected countries are. As a result, many of the dead — 60, according to Vox’s Julia Belluz — are healthcare workers.

Last week, World Health Organization Director-General Dr. Margaret Chan announced the launch of a $100 million response plan to bring the outbreak under control. On a July 31st CDC telebriefing, CDC Director Dr. Tom Frieden announced, “Over the next 30 days we’ll be deploying another 50 Epidemic Intelligence Service officers, other epidemiologists, and health communications experts to the affected area.” (As of July 28th, 12 CDC staff members were there already.) Frieden summarized the task that awaits those responding to the epidemic:

In past outbreaks, we have been able to stop every outbreak.  But it takes meticulous work.  It’s like fighting a forest fire.  If you leave behind even one burning ember, one case undetected, it could reignite the epidemic.  Difficult as it is, it can be done.  I’m confident that as we make progress over the coming weeks and months, we will not only begin to tamp down these outbreaks, but leave behind stronger systems that will be able to find, stop before they spread and prevent more effectively Ebola and other health threats.

… We are not going to treat or vaccinate our way out of these outbreaks.  We are going to use the traditional means that work of case identification, isolation, contact tracing, health communication, good meticulous management.  That’s what has stopped every Ebola outbreak that’s ever happened before.  That’s what will stop this Ebola outbreak.

… This is a marathon, not a sprint.  This is going to take at least three to six months, even if everything goes well.  We have challenges with security and health care systems that make it not the best of conditions.

Frieden stressed that “Ebola poses very little risk to the general US population.” CDC has issued a Level 3 travel warning, urging people to cancel non-essential travel to Guinea, Liberia, and Sierra Leone. The agency has also issued a Health Alert Notice to US healthcare workers emphasizing steps to identify potential cases and prevent the spread of infections from any patients with Ebola who arrive in the US. The focus now, however, is on halting Ebola transmission in West Africa and preventing an already awful epidemic from becoming even more widespread.