New animal-to-human diseases likely to increase
Researchers blame global warming, increased urbanization and environmental disruption.
Mon, Jan 04, 2010 at 07:50 PM
Increased environmental disruptions, global warming and urbanization are set to trigger new pandemics of infectious diseases, according to a recent story by The Independent.
At least 45 diseases that have passed from animals to humans have been reported to U.N. agencies in the last two decades, with the number expected to escalate in the coming years, according to the report. These emerging and re-emerging diseases, which have jumped the human-animal species barrier in record numbers, include malaria, lyme disease, Hantavirus, West Nile disease and schistosomiasis.
"We appear to be undergoing a distinct change in global disease ecology. The recent emergence of infectious diseases appears to be driven by globalization and ecological disruption," said Dr. Montira Pongsiri, an environmental health scientist at the U.S. EPA, adding that previous transitions in human history have also had devastating impacts in terms of spreading diseases.
The most well-known case of a disease that jumped from animals to humans is HIV, the virus that causes AIDS. HIV is thought to have crossed from chimpanzees to humans in West Africa in the last century. Since then, more than 25 million people worldwide have died from it.
The swine flu pandemic is a more recent example of a disease jumping from animals to humans. It is thought to have emerged in Mexico as a result of the mixing of viruses that infected pigs, humans and birds, which then created a new pandemic strain. Though that particular strain turned out to be milder than predicted, future flu pandemics could have higher death rates and infect more people, warn researchers.
Though the number of people who succumbed to infectious diseases fell sharply in the developed world during the industrial revolution, the rise of manufacturing and pollution levels increased the incidence of chronic diseases including cancer, allergies and birth defects, according to Pongsiri and colleagues.
This time, the surge in diseases is being driven by the destruction of plant and animal habitats, the loss of species and changes that have brought more humans into closer contact with animals than at any stage in human history.
"Since 1940, over 300 new diseases have been identified, 60 percent of which crossed to humans from animals and 70 percent of these came from contact with wildlife. I would expect the emergence of new diseases from contact with animals to continue in this century,” said David Murrell, a lecturer in ecology at University College London.
And, as urbanization and globalization increase, it’s all the more likely that these diseases will increase as well.
“There is no evidence to suggest this is going to end any time soon," said Dr. Jan Slingenbergh of the United Nations Food and Agriculture Organization. "Agriculture looks set to continue growing for another two decades, and we are only at the beginning of climate change.”