The United States' top disease detective calls Ebola a ''painful, dreadful, merciless virus.''
The World Health Organization has declared the outbreak in West Africa an international emergency, killing more than 900 people and spreading.
That's scary and serious. But it also cries out for context.
AIDS alone takes more than a million lives per year in Africa - a thousand times the toll of this Ebola outbreak so far.
Lung infections such as pneumonia are close behind as the No. 2 killer. Malaria and diarrhea claim hundreds of thousands of African children each year.
In the United States, where heart attacks and cancer are the biggest killers, the risk of contracting the Ebola virus is close to zero.
Americans fretting about their own health would be better off focusing on getting a flu shot this fall. Flu is blamed for about 24,000 U.S. deaths per year.
To put the Ebola threat in perspective, here are some reasons to be concerned about the outbreak, and reasons not to fear it:
WHY IT'S SCARY
There is no cure for Ebola hemorrhagic fever.
More than half of people infected in this outbreak have died. Death rates in some past outbreaks reached 90 percent.
It's a cruel end that comes within days. Patients grow feverish and weak, suffering through body aches, vomiting, diarrhea and internal bleeding, sometimes bleeding from the nose and ears.
The damage can spiral far beyond the patients themselves.
Because it's spread through direct contact with the bodily fluids of sick patients, Ebola takes an especially harsh toll on doctors and nurses, already in short supply in areas of Africa hit by the disease.
Outbreaks spark fear and panic.
Health workers and clinics have come under attack from residents, who sometimes blame foreign doctors for the deaths. People with Ebola or other illnesses may fear going to a hospital, or may be shunned by friends and neighbors.
Two of the worst-hit countries - Liberia and Sierra Leone - sent troops to quarantine areas with Ebola cases. The aim was to stop the disease's spread but the action also created hardship for many residents.
WHERE IT IS
The outbreak began in Guinea in March before spreading to neighboring Sierra Leone and Liberia. A traveler recently carried it farther, to Nigeria, leading to a few cases in the giant city of Lagos.
Ebola emerged in 1976. It has been confirmed in 10 African