Ack! Kill all the animals NOW!

Scary stuff indeed from the London Times:

At least one new disease is jumping the species barrier from animals to human beings every year, exposing people to emerging germs at a rate that may be unprecedented.

The first work to catalogue the range of germs capable of infecting people has disclosed that 38 new human pathogens have emerged in the past 25 years. Three quarters of these, including Aids, avian flu, Sars and new variant CJD, originated as animal diseases.

The survey, led by Mark Woolhouse, of the University of Edinburgh, has identified more than 1,400 pathogens that can cause disease in human beings, at least 800 of which crossed the species barrier from animals.
While it is not known whether the rate at which diseases are jumping species is accelerating, Dr Woolhouse said it was impossible that human beings had been exposed to so many new pathogens so quickly through most of history.

Changes in human behaviour and the environment, such as bushmeat hunting, intensive agriculture, the ease of long-distance travel and global warming, were all likely to be helping animal germs to acquire the ability to infect people.

“The rate of accumulation we are seeing now is too fast to be supported over an evolutionary timescale,” he told the American Association for the Advancement of Science conference in St Louis yesterday. “We would be overrun with pathogens.

“Either many of these pathogens will not persist in humans, or there is something very unusual about the present time. The most obvious explanation is the pace and scale of change in the ways humans interact with their environment, providing new opportunities for humans to be exposed to and to transmit novel pathogens.”

The deadliest example of a germ that has recently crossed from animals to human beings is HIV, which is thought to have started out as a monkey or ape virus in Africa. Other conditions with an animal origin include the Ebola and Marburg haemorrhagic fevers, the coronavirus that causes Sars, the West Nile virus that is now endemic in the United States and H5N1 avian flu.

The class of pathogen most responsible for new human infections is the RNA viruses, which include HIV and influenza. These seem particularly adept at jumping species because they have small genomes that mutate easily, allowing them to adapt to new hosts.