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Professor Marie Pizzorno, biology, is a virologist specializing in the molecular biology of viruses that infect honeybees. She has closely monitored the latest Ebola epidemic — now the worst outbreak of the deadly African virus in history — since its inception. In this edition of Bucknell Answers, Pizzorno explains what Ebola is and what doctors can do to control it.
Question: Where does Ebola come from, and how do humans contract it?
Answer: There are five known species of Ebola. We believe that four originally come from Africa. Another, which does not seem to make humans sick, appears to come from Asia. We think there is an animal in Africa that carries this virus around that doesn't seem to be hurt or affected by it, and people become infected by that animal, setting off a chain of transmission among humans. That animal is probably a fruit bat. A relative of Ebola called Marburg virus has been found definitively in them, and there's evidence to suggest Ebola also could live in a fruit bat.
Then there is the practice in Africa of eating bush meat. People don't always go to the grocery store for meat; they hunt their own. If they hunt a fruit bat, they could get it directly from that bat. The bat could also transmit it to another species such as a chimp, ape, small monkey or even a deer, and when humans butcher that animal, they can get Ebola.
Question: How does Ebola attack the body and what are its symptoms?
Answer: Ebola is fascinating in its ability to cause disease, and I've had students in my virology class read papers about it. It can attack a lot of different systems in the body. The one place it doesn't appear to attack is the lungs, which is a good thing. If it replicated in the lungs it would be more easily transmitted through aerosols, the way colds and flus are transmitted. Ebola primarily goes after the lymphatic system, and the spleen and liver are the major places where it tends to replicate. There is also evidence it could replicate on the inside of your blood vessels, which is why people leak bodily fluids and blood. The gut is another area it affects. People tend to have symptoms of stomach pain, nausea and diarrhea with Ebola because it can attack the lining of the gut. Unfortunately it's pretty voracious. Eventually people go into shock before they die, because they're leaking so much fluid out of their blood vessels. It's pretty ugly.
Question: How is it treated?
Answer: We don't have any good anti-viral drugs to treat Ebola. There's no vaccine, though several have been in the works that they're field-testing right now. That would be great for health-care workers, who put themselves on the front line.
There are also a lot of experimental treatments. ZMapp is really interesting. It's actually a group of antibodies. They've identified these antibodies that humans could make, but that everyone might not make, that can attack the virus. It's part of your normal immune system, and they think it attacks the Ebola virus and might boost your immune system to help get rid of it faster. It's just a protein, an antibody. It's not a classic drug the way we think of an antibiotic, which is usually a small molecule that attacks bacteria.
Question: Why has this outbreak been so much worse than before?
Answer: Outbreaks have appeared more frequently in the last 10 or 20 years because we know what to look for. There have been flare-ups of Ebola outbreaks, usually in central Africa around Zaire and Sudan. Those countries have gotten good at identifying and shutting them down pretty quickly, so the last several epidemics have been limited to only a few dozen cases.
West Africa doesn't have experience dealing with Ebola, so when this outbreak hit West Africa, it wasn't contained. The medical containment facilities — labs to test for it, and enough gloves, gowns and masks — just weren't in place to shut it down, and it's taken off a bit more than anybody thought it would. Another thing is that in this part of Africa, people travel between countries very freely. The borders are very porous, and people move back and forth for work or shopping. So once it happened in one country, it was probably transmitted easily to other countries through people's normal movements.
Question: The U.S. has seen several cases of Ebola transmission. How likely is a larger outbreak?
Answer: I think everyone was expecting at least one case in the U.S., and it's not too surprising it spread to health-care workers. Even though nurses and doctors in this country train to deal with highly infectious diseases, most of them have never really had to work with them. One of the great triumphs of modern medicine is that we've eliminated really bad diseases like smallpox, so most doctors don't train under highly infectious disease conditions. Doctors were told in the '60s and '70s, "Don't study infectious diseases. We've cured them all." Then HIV hit, and now we're seeing all sorts of diseases coming out of tropical parts of the world. Even though our doctors know what to do, putting best practices into action is difficult.
But we are able to track the people who have had contact with infected patients, get them into quarantine and hopefully draw a line around those people to keep it from spreading any further. I'm not terribly worried it will get much further than the few people that have been identified so far, though we might see more small flares.
Question: What can we sort of learn from this outbreak?
Answer: There are times some rights may have to suffer in order to keep a larger community healthy. There is precedent for that in this country. We used to fine people who were not vaccinated for smallpox, because we had a vaccine, and that was effective in preventing its spread. With Ebola, individuals may have to be quarantined against their will, because if you've got a deadly infectious disease like Ebola, you can't just wander around giving it to other people. You have to be contained. We have to know where you are and that you're not spreading it to other people. The virus doesn't care about human rights. The virus just cares about getting to the next host.
Question: So should we restrict flights from Africa and impose broad quarantines, as some have suggested?
Answer: No. I think we need to track people who are traveling from West Africa. Five U.S. airports have now instituted intensive screening, so they quarantine and test anybody coming in with a fever or other disease symptom. That's probably the best we can do. We wouldn't have found the one patient who did come in, because he wasn't symptomatic when he flew. The good thing about Ebola, if there is one, is you can't transmit it until you actually have a fever and show symptoms. You don't have enough virus in your body yet to give it to somebody else.
Keeping fear and panic under control is also important. We're going to have to trust organizations like Doctors without Borders, the World Health Organization and the CDC to get a handle on this and contain it. A lot of television shows and movies have dealt with this sort of world pandemic that can infect every person on the planet, but we shouldn't think that's what will happen here. I don't think it will.