It took only moments to feel the impact of what was happening here . We had just landed in Conakry , the capital of Guinea . In the fields right outside the airport , a young woman was in tears . She started to wail and shout in Susu , one of the 40 languages spoken in this tiny country of 12 million people . The gathered crowd became silent and listened intently . The young man sitting next to me quietly translated , although I already had my suspicions . He told me the woman 's husband had died of Ebola , and then quickly ushered us away . It is probably not surprising the airplane bringing us into Conakry was nearly empty , as are all the hotels here . Not many people in the United States have ever visited Guinea , or could even identify where it sits in West Africa . It is already one of the world 's poorest countries , and the panic around Ebola is only making that worse . Some of it is justified . That 's because this time , the outbreak is different . In the past , Ebola rarely made it out of the remote forested areas of Africa . Key to that is a grim version of good news/bad news : because Ebola tends to incapacitate its victims and kill them quickly , they rarely have a chance to travel and spread the disease beyond their small villages . Now , however , Ebola is in Conakry , the capital city , with 2 million residents . Equally concerning : it 's just a short distance from where we touched down , at an international airport . It has gone `` viral , '' and now the hope is that it does n't go global . Ebola : What you need to know . When I asked doctors on the ground about that scenario , they had split opinions . Several told me the concern is real but unlikely . Most patients with Ebola come from small villages in the forest and are unlikely to be flying on international trips , they told me . Furthermore , they do n't think Ebola would spread widely in a western country ; our medical expertise and our culture -- not touching the dead -- would prevent it . Others are n't so sure . No one wants to test that theory . WHO : Ebola outbreak one of 'most challenging ' With Ebola , there is an incubation period of two to 21 days . Remember these numbers . This is the range of time it takes to develop symptoms after someone has been exposed . With an international airport close by , that means you could be on the other side of the world before you develop the headache , fever , fatigue and joint pain which make up the early symptoms of an Ebola infection . The diarrhea , rash and bleeding come later . Hiccups is a particularly grave sign with Ebola . It means your diaphragm , which allows you to breathe , is starting to get irritated . There is a lot we know about Ebola , and it scares us almost as much as what we do n't know . We do know Ebola , a simple virus with a small genome , is a swift , effective and bloody killer . The mortality rate is higher than 50 % and in some outbreaks reaches 90 % . Ebola appears to kill in a clever way . Early on , it strategically disarms your immune system , allowing the virus to replicate unchecked until it invades organs all over your body . It convinces your blood to clot in overdrive , but only inside your blood vessels . While those blood vessels choke up , the rest of your body starts to ooze because the clotting mechanisms are all busy . You start to hemorrhage on the outside of your body . Nose bleeds , bruising , even a simple needle stick will refuse to clot . But , it is the bleeding you do n't see -- the bleeding on the inside -- that causes even more catastrophic problems . Many patients die of shock , within an average of 10 days . What is ebola ? It sounds like the stuff of horror movies . But despite the real danger , Ebola is not at all easy to `` catch . '' If it were , my wife would have refused to let me come in the midst of an outbreak . To become infected , you generally need to spend extended time with someone who is gravely ill , and come into contact with his or her infected body fluids . That 's why family members and health care workers are the most likely to get sick . Over the last three weeks , at least 112 people have died , including 14 health care workers . With some infections , you can shed and spread the virus long before you get ill. That 's not the case with Ebola . It 's only after you are sick and feverish do you become contagious . However , it only takes a miniscule amount to infect and kill . A microscopic droplet of blood or saliva on your bare hand could enter through a break in your skin . And , whether you realize it or not , we all have breaks in our skin . Since I was a kid , I have been fascinated with outbreaks . I learned in medical school that new pathogens generally make a jump from animals to humans , a process called zoonosis . This is happening in areas where human and animals come into continuous contact . David Quammen refers to it as `` Spillover , '' in his book of the same name . A stew of ducks , geese , chickens , pigs and humans in southeast Asia led to the spillover of avian flu , H5N1 . Contact between pigs and humans in Mexico led to swine flu , H1N1 ; pigs and fruit bats were the recipe for Nipah fever in Malaysia . The best guess is that fruit bats may be a natural reservoir for the Ebola virus too , but this has not been confirmed . Quammen makes the point : Ebola did n't enter our world -- we entered its world . Pathogens can be predators , like lions , tigers and bears . A virus may not plan the way a big cat does , but in a sense it stalks its prey -- waiting for the moment of opportunity , then attacking with fury . Because it can lie silent for years , it 's also easy to see Ebola as a killing ghost , like Jack the Ripper . Presumably outbreaks begin through some human-animal contact , but since that contact is ongoing we do n't know what it is that leads Ebola to rear its ugly head . We do n't know how to treat the illness or vaccinate against it . We certainly do n't know how to cure it . I thought about all of this as I left that woman in the airport , and I have thought about her a great deal since then . Her grief made an impression on all of us . It also made this mysterious , exotic virus the world knows , but does n't fully understand , so much more real and frightening . For the next 21 days ( the outer range of the incubation period ) the woman we saw will be monitored for a fever or any early signs she may have contracted Ebola from her husband . If she exhibits symptoms , she will be isolated and treated with fluids , oxygen and nutrition . That is all that can really be offered . Again , there is no cure for Ebola . For her neighbors , in Guinea and across its border , another critical number is 42 -- as in 42 days , or two incubation periods . If the health care teams here do n't see any new cases during that time then they officially say the outbreak is over . We are not there yet , not even close . The clock is ticking . How to help .
Dr. Sanjay Gupta is in Guinea reporting on the Ebola outbreak . The Associated Press contributed to this report. It has gone `` viral , '' and now the hope is that it does n't go global , Gupta says . Ebola , a simple virus with a small genome , is a swift and bloody killer .