Sorry, clean freaks. No matter how well you scrub your home, it's covered in bacteria from your own body. And if you pack up and move, new research shows, you'll rapidly transfer your unique microbial fingerprint to the doorknobs, countertops and floors in your new house, too.

In fact, researchers who studied seven families in Illinois, Washington and California could easily match up who lived where using their microscopic roommates.

Air pollution, smoking, obesity and accidents, especially on the road, kill at least 4.7 million Chinese a year and cost the country tens of billions of dollars, researchers said on Friday.

In an overview published in The Lancet, they said China had in some respects made great strides in health, boosting the average lifespan from 40 years in 1950 to 76 years in 2011 and rolling back many infectious diseases.

The Ebola outbreak in West Africa is accelerating and could grow six times larger to infect as many as 20,000 people, the World Health Organization said Thursday. The U.N. health agency unveiled a new road map for containing the virus, and scientists are fast-tracking efforts to find a treatment or vaccine.

Ebola has menaced Africa for 40 years, but previously struck in remote villages and was contained fairly quickly. This time, it has spread to major cities in four countries, provoking unrest as whole neighborhoods and towns have been sealed to the outside.

Ebola-hit nations met for crisis talks on Thursday as the death toll topped 1,500 and the World Health Organization warned that the number of cases could exceed 20,000 before the outbreak is stemmed.

Nigeria announced that the virus had reached its oil-producing hub, dashing hopes that the country had successfully contained it to its biggest city, Lagos.

The international response to West Africa's Ebola outbreak is "dangerously inadequate," said the emergency coordinator for Doctors Without Borders (Medecins sans Frontieres) in Sierra Leone on Wednesday.

"The Ebola outbreak has been out of control for months, but the global health community has taken a long time to react," wrote nurse Anja Wolz in the New England Journal of Medicine.

Emotions connected to memories can be rewritten, making bad events in the past seem better and good things appear worse, scientists from Japan and the United States have found.

The discovery of the mechanism behind the process helps to explain the power of current psychotherapeutic treatments for mental illnesses such as depression or Post Traumatic Stress Disorder (PTSD), they said, and could offer new avenues for psychiatric help.

More than a dozen landmarks across the U.S. and Canada will light up to promote next week's "Stand Up to Cancer" telethon.

Organizers say the buildings that will be illuminated starting Thursday include Rockefeller Center in New York, Toronto's CN tower and the Wrigley Building in Chicago.

Japanese health officials said Thursday that three young people have contracted dengue fever, the first such infections in the country in nearly 70 years.

The three are suspected of having contracted the disease when they were bitten by mosquitos in Yoyogi Park in central Tokyo, officials said.

India has asked U.S. soft drinks giant PepsiCo to reduce the sugar content of its sodas as the country battles growing levels of obesity and diabetes.

PepsiCo chairman Indra Nooyi met food processing industry minister Harsimrat Kaur Badal during a visit to India on Tuesday to discuss its plans for healthier options and investing in India.

A World Health Organization (WHO) employee who has contracted Ebola arrived in Germany Wednesday, the first patient with the virus to be treated in the country, officials said.

A plane carrying the patient -- a Senegalese epidemiologist who was infected in Sierra Leone -- touched down at the airport of the northern city of Hamburg and was to be taken to a hospital isolation ward.