Putting Ebola's risks into perspective

The diagnosis of the first Ebola patient on U.S. soil this week may have put people in a panic, fearing the exotic virus more than mundane germs – such as influenza – that pose a far greater threat to the average American.

The Ebola outbreak in West Africa – the largest in the 40-year history of the virus – has infected 7,178 and killed 3,338, according to the World Health Organization.

Still, because Ebola is rare and relatively difficult to transmit, it kills far fewer people than diseases of which Americans are no longer afraid, such as measles and influenza, says Peter Hotez, dean of the National School of Tropical Medicine and professor at Baylor College of Medicine in Houston.

"It's important to keep these things in perspective," says Lisa Maragakis, associate hospital epidemiologist at the Johns Hopkins Hospital in Baltimore.

She compared Americans' fear of Ebola to the fear of flying. Though many people are afraid to fly, Maragakis points out that far more people are killed in cars.

•Influenza, which many people mistake for a "bad cold," claims up to 49,000 lives a year and sends more than 200,000 to the hospital, according to the Centers for Disease Control and Prevention. Half of the more than 100 children who died from flu in the USA last year were healthy kids with nothing to suggest they were more vulnerable than other children.

•Measles, one of the most infectious diseases in the world, is far easier to catch than Ebola. If a person with measles comes in contact with 10 susceptible people — those who have never had measles or who are unvaccinated — nine of those people will come down with measles, says Julia Shaklee Sammons, medical director of infection prevention and control at the Children's Hospital of Philadelphia.

On average, people with measles spread the disease to 12 to 18 other people, according to the Michigan Center for Public Health Preparedness. In contrast, people with Ebola in West Africa spread the disease to one to two others, according to the WHO.

Unlike Ebola, measles spreads through the air. The measles virus is so hardy that it can linger in the air for two hours after an infected person leaves the room – and still infect the next person to walk by, according to the WHO.

Measles is much stealthier than Ebola. People infected with measles can spread the virus for four days before breaking out in tell-tale red spots, according to the WHO.

Even with a mortality rate of 2% to 15% — far lower than the 70% mortality rate seen in the West African Ebola outbreak — measles kills 122,000 people around the world each year, Hotez says. Before vaccines, measles killed 2.2 million every year.

•Norovirus, the most common cause of both food-borne illness and stomach-related misery in the USA, can live on surfaces for days, so people can pick up the virus just from touching a door handle or a toy, Sammons says.

Norovirus – which causes diarrhea, vomiting and stomach cramps – afflicts up to 21 million Americans a year and kills up to 800, according to the CDC.

If Ebola spread that easily, there would be millions of cases, not thousands, Hotez says.

"In general, Ebola is not easy to get," Sammons says.

Unlike people with measles, patients infected with Ebola can spread the virus only after they begin to show symptoms, such as a fever, Tom Frieden, director of the CDC, said at a news conference Tuesday. Ebola can't spread through the air. It can spread only through direct contact with bodily fluids, primarily blood, Sammons says.

Chances are, anyone exposed to Ebola is going to know about it, Sammons says. That gives them time to seek medical help and isolate themselves to prevent them from spreading the virus.

Ebola could be far less lethal in a developed country that has access to modern intensive care and basic measures, such as keeping patients hydrated and maintaining a steady blood pressure.

One reason Ebola has spread so widely in Africa – in spite of all of these obstacles – is that the countries most affected are extremely poor. Many people lack running water and soap in their homes. So do many hospitals, according to the CDC.

If one family member comes down with Ebola, there's a good chance that others in the home will become infected, especially if patients bleed and vomit profusely. Families without modern toilets and washing machines have trouble cleaning up after patients who lose control of their bowels and produce huge amounts of diarrhea.

Even burying the dead can spread Ebola in these countries, because common burial rites involve washing the dead and preparing the bodies.