MUSIC: "Our World" theme
This week on Our World: The World Health Organization declares a swine flu pandemic ... A potential new weapon in the fight against termites ... and coral reefs under threat ...
PATTERSON: "We've got to work very hard to protect them because it shows us how the ecosystem should look and used to look around the planet before things started to go downhill."
Those stories, horseback riding as therapy, our Website of the Week, and more.
I'm Art Chimes. Welcome to VOA's science and technology magazine, "Our World."
The World Health Organization on Thursday declared its first pandemic in four decades and bumped the H1N1 swine flu threat level up to phase six, the highest alert level.
WHO official Margaret Chan told reporters in Geneva that public health officials identified this pandemic earlier than any previous outbreak, and that it is - so far at least - not nearly as deadly as prior pandemics.
CHAN: "Globally, we have good reason to believe that this pandemic, at least in its early days, will be of moderate severity. As we know from experience, severity can vary, depending on many factors, from one country to another."
Dr. Chan said WHO continues to recommend against border closures or other travel restrictions.
As of the announcement, more than 28,000 cases of H1N1 influenza in 74 countries have been reported to the WHO, including 144 deaths.
The WHO announcement coincides with the release of a study of the origins of the H1N1 virus. Writing in the journal Nature, an international team of scientists reports that the disease actually moved from pigs to humans several months before it was first recognized, in April.
The researchers say their study indicates the need for better monitoring of developing infectious diseases.
Swine flu might be scary, but year-after-year, tuberculosis is a much bigger public health problem.
Now, Swedish researchers say they may have figured out how tuberculosis can hibernate in humans, becoming active only long after the original infection. The latent form of TB is carried by an estimated one-third of the world's population, and most people never get sick.
As we hear from VOA's Jessica Berman, it appears TB may form inactive spores which suddenly spring to life in some individuals.
BERMAN: Every year, 10 million new cases of tuberculosis are diagnosed around the world and 2 to 3 million people die of the lung disease. Many of them have been infected with a latent form of the tuberculosis bacteria that can become active and cause the illness. But many others are infected without ever getting sick. Scientists have been trying to figure out why.
In new research, scientists at Sweden's Uppsala University found evidence that a relative of the tuberculosis bacteria (called mycobacterium marinum) that causes tuberculosis in fish forms hibernating spores when scientists cultured the microorganism in the laboratory. Another similar bacterium, which causes tuberculosis in cows but can also infect humans, also forms spores.
Lead investigator Leif Kirsebom says scientists don't understand the molecular mechanism that causes the TB mycobacterium to remain silent in human cells - for decades, in some cases - and then spring to life. But the scientists' work suggests the microorganism goes into hiding by forming spores when it is under environmental stress.
Kirsebom says discovery of the spores may open a new chapter in the study of mycobacteria, including an aggressive microbe (mycobacterium ulcerans} that causes disfiguring skin lesions called Buruli ulcer disease.
KIRSEBOM: "It might, it might, I say might, shed light on perhaps spread of disease - for example mycobacterium Buruli ulcerans which causes Buruli ulcer in Africa - and the transmission of those bacteria. Also, it (may) open new avenues of latent infection caused by mycobacteria."
BERMAN: So far, Kirsebom says the spores have not been detected in mycobacterium tuberculosis, which causes most cases of human TB.
Kirsebom says if it turns out the microorganism does not form spores that would also give scientists valuable information about the behavior of latent TB in humans.
Kirsebom says discovery of the spores in marine and cow versions of the bacteria could eventually pave the way for treatments to stop latent tuberculosis from becoming active in humans.
KIRSEBOM: "It opens a new biology to study and understand (mycobacteria). And if you understand there might be new targets, there might be new ways, for example, [to] understand how the mycobacteria grows."