The Ebola outbreak centered around West Africa is starting to get a bit too interesting. As of July 20, some 1,093 people in Guinea, Sierra Leone and Liberia are believed to have been infected by Ebola since symptoms were first observed four months ago.

Testing confirmed the Ebola virus in 786 of those cases, and 442 of those people died. Of the 1,093 confirmed, probable and suspected cases, 660 of those have died. Since then the number of infected has risen to at least 1,201, and 672 have died according to the World Health Organization.

Now there is potential that the disease could spread to an even wider population, as an air traveler hopped an international flight Tuesday from Monrovia, Liberia to Lagos, Nigeria, Africa’s largest city with 21 million people, via a stopover in Lome, Togo.

Airports in these countries are on alert, but they have weak screening systems in place to prevent possible Ebola victims from traveling, and it’s not often easy to identify a person who is infected. Ebola has a variable incubation period of between two and 21 days, and can’t be diagnosed on the spot. Also it’s a tricky virus, as the initial symptoms, such as fever, headache, sore throat, and fatigue, mask themselves as other more common illnesses, before escalating to vomiting, diarrhea, and internal and external bleeding.

This current outbreak is already the deadliest on record, and concern has increased in Nigeria where many live in cramped conditions, that a disease such as Ebola could spread like wildfire.

There is no known cure for this highly contagious virus, which is one of the world’s deadliest.

The infected air traveler, Patrick Sawyer, was a consultant for the Liberian Ministry of Finance, and reportedly did not show Ebola symptoms when he boarded the plane Tuesday, but by the time he arrived in Nigeria he was vomiting and had diarrhea. He was dead by Friday.

Blood tests from Sawyer confirmed he died of Ebola. The nearly 50 other passengers onboard are being monitored for signs of Ebola but are not being kept in isolation. It was learned that Sawyer’s sister had also died of Ebola in Liberia, but he claimed to have had no contact with her.

Ebola is highly contagious and typically kills 90 percent of the people infected, but with early treatment, this current outbreak has a death rate of roughly 70 percent. Ebola is passed by touching bodily fluids of patients even after they die. Traditional burials in this area of the world can include rubbing the bodies of the dead, which contributes to the spread of the disease.

Ebola isn’t contagious until symptoms appear, but because the incubation period varies and symptoms don’t always appear immediately, the virus can easily spread as people travel around the West African region. Once infected with the virus, many people die in an average of 10 days as the blood fails to clot and hemorrhaging occurs.

Two American aid workers in Monrovia, Liberia have tested positive for Ebola. Nancy Writebol, a Charlotte, NC resident, tested positive Friday, and on Saturday, Dr. Kent Brantly, of Fort Worth, Texas, had a positive result. Both were helping to treat Ebola patients.

Also on Saturday, Dr. Samuel Brisbane died in Liberia after he had previously contracted the disease during his treatment of Ebola patients at John F. Kennedy Memorial Medical Center in Monrovia.

These incidents come on the heels of the confirmation of another doctor, Sheik Umar Khan, who has played a key role in fighting the Ebola outbreak in Sierra Leone, was found infected with the disease.

The first case in Sierra Leone, which has posted the highest infection numbers recently, originated in Freetown, the capital, when a hairdresser became ill. Her family forcibly removed her from a government hospital, sparking a frantic search that ended Friday, when it was confirmed she had died while being transported to a treatment center in the east of the country.

The West African outbreak is believed to have begun as far back as January in southeast Guinea, though the first cases weren’t confirmed until March.