Skip to main content

Scientists See Growing Animal-Disease Risk

Veterinarians depart after inspecting a poultry farm in Navapur, in the western Indian state of Maharashtra, Sunday, Feb. 19, 2006. Wearing protective gloves and masks, health officials and farm workers slaughtered thousands of chickens in western India Sunday, a day after the country reported its first outbreak of bird flu. (AP Photo/Ajit Solanki)Humans risk being overrun by diseases from the animal world, according to researchers who have documented 38 illnesses that have made that jump over the past 25 years.

That's not good news for the spread of bird flu, which experts fear could mutate and be transmitted easily among people.

There are 1,407 pathogens — viruses, bacteria, parasites, protozoa and fungi — that can infect humans, said Mark Woolhouse of the University of Edinburgh in Scotland. Of those, 58 percent come from animals. Scientists consider 177 of the pathogens to be "emerging" or "re-emerging." Most will never cause pandemics.

Experts fear bird flu could prove an exception. Recent advances in the worldwide march of the H5N1 strain have rekindled fears of a pandemic. The virus has spread across Asia into Europe and Africa.

Controlling bird flu will require renewed focus on the animal world, including the chickens, ducks and other poultry that have been sacrificed by the tens of millions to stem the progress of the virus, experts said at a news conference late Sunday at the annual meeting of the American Association for the Advancement of Science.

"The strategy has to be looking at how to contain it in the animal world, because once you get into the human side, you're dealing with vaccines and antiretrovirals, which is a whole new realm," said Nina Marano, a veterinarian and public health expert with the National Center for Infectious Diseases.

Bird flu has killed at least 91 people — most of them in Asia — since 2003, according to the World Health Organization. It appears to kill about half the people it infects. However, should it mutate so it can pass from human to human, it likely will grow far less deadly, said Dr. Stanley Lemon, of the University of Texas Medical Branch at Galveston.

"It is very unlikely that it would maintain that kind of case mortality rate if it made the jump," Lemon said.

Each year for the last 25 years, one or two new pathogens and multiple variations of existing threats have infected humans for the first time. Without speculating about earlier infection rates, Woolhouse told reporters it appears impossible the human species could endured such a rapid pace of new infections over thousands of years.

"Humans have always been attacked by novel pathogens. This process has been going on for millennia. But it does seem to be happening very fast in these modern times," Woolhouse said.

Woolhouse argues that either many of those diseases and other afflictions will not persist in humans or that there is something peculiar today allowing so many of them to take root in humans.

One explanation may be the recent and wide-scale changes in how people interact with the environment in a more densely populated world that is growing warmer and in which travel is faster and move extensive, Marano said. Those changes can ensure that pathogens no longer stay restricted to animals, she added. Examples from recent human history include HIV, Marburg, SARS and other viruses.

That prospect leaves open the question of what future threats await humans.

"It always surprises us. We think that avian flu will be the next emerging disease. My guess is something else might come out before that," said Alan Barrett, of the University of Texas Medical Branch at Galveston. "It's very hard to anticipate what comes next."

Comments

Popular posts from this blog

Does light have mass?

The short answer is "no", but it is a qualified "no" because there are odd ways of interpreting the question which could justify the answer "yes". Light is composed of photons so we could ask if the photon has mass. The answer is then definitely "no": The photon is a massless particle. According to theory it has energy and momentum but no mass and this is confirmed by experiment to within strict limits. Even before it was known that light is composed of photons it was known that light carries momentum and will exert a pressure on a surface. This is not evidence that it has mass since momentum can exist without mass. [ For details see the Physics FAQ article What is the mass of the photon? ]. Sometimes people like to say that the photon does have mass because a photon has energy E = hf where h is Planck's constant and f is the frequency of the photon. Energy, they say, is equivalent to mass according to Einstein's famous formula E = m

Hackers biting Apple

Hackers are increasingly focusing on Apple's Mac OS X, and the number of newly discovered vulnerabilities has surged. Such a switch could mean big implications for Apple's user base, which has traditionally not had to concern itself too much over security. It's been an impressively quiet year so far on the PC virus and worm front, and hackers seem to be focusing their attention elsewhere. One such area is Apple's Mac OS X. Once mostly ignored by malware developers, there appears to be a growing interest in this "alternative" OS. Details Have you noticed the dearth of serious PC virus and worm threats out there lately? Well, it isn't a figment of your imagination -- according to vnunet.com, viruses are no longer the top security threat . While serious attacks are still likely to emerge, the bottom has apparently fallen out of the PC antivirus market -- just as Microsoft begins a big push into the security market. One cause of this drop-off is solidif

Play against Xbox360 gamer on PC in Vista

Microsoft Corp. co-founder Bill Gates on Tuesday announced a cross-platform gaming service that integrates games played on cell phones, Xbox 360 consoles and the upcoming Windows Vista operating system. The "Live Anywhere" service will be available as part of Windows Vista, Microsoft's next-generation PC operating system. The consumer version is scheduled for release early next year. "It means that you have one online community," Gates said in a news conference. "This platform can really unleash developers to do amazing new things." The system would extend the company's existing Xbox Live service for the Xbox 360 console into millions of Internet-enabled PCs and cellular phones. No pricing information on the new service was announced. In recent months, Microsoft has been pushing a number of online services that it hopes will boost revenue as markets for its traditional software become increasingly saturated. The company expects to make money off s