Tuesday, January 5, 2010

Environmental disruption set to trigger new pandemics, scientists warn

The following article was referenced on the Avian Flu Diary, and is directly relevant to much of CARE's current work and future vision in emerging and re-emerging infectious diseases. Excerpts are presented below, but the entire article is worth reading.

The article goes on to highlight key zoonotic diseases such as HIV(AIDS), hantaviral diseases, H5N1/H1N1 influenzas, rabies, malaria, and West Nile; diseases which have emerged in humans after their respective infectious agents jumped the species barrier from animals to infect and subsequently trigger disease states in humans.

Deadly animal diseases poised to infect humans: Environmental disruption set to trigger new pandemics, scientists warn

By Jeremy Laurance, Health Editor, The Independent

"The world is facing a growing threat from new diseases that are jumping the human-animal species barrier as a result of environmental disruption, global warming and the progressive urbanisation of the planet, scientists have warned.

At least 45 diseases that have passed from animals to humans have been reported to UN agencies in the last two decades, with the number expected to escalate in the coming years.
Dramatic changes to the environment are triggering major alterations to human disease patterns on a scale last seen during the industrial revolution. Montira Pongsiri, an environmental health scientist at the US Environmental Protection Agency in Washington, says that previous transitions in human history have had a devastating impact in terms of the spread of disease.

'We appear to be undergoing a distinct change in global disease ecology. The recent emergence of infectious diseases appears to be driven by globalisation and ecological disruption,' Dr Pongsiri said.

He and eight colleagues examined five emerging and re-emerging diseases – malaria, lyme disease (spread by ticks), Hantavirus (spread by mice and rats), West Nile disease (spread by mosquitoes), and schistosomiasis (spread by freshwater snails). They argue that changes in land use, farming practices and climate lie behind the increasing number of outbreaks.

The best known example of a disease that jumped the animal-human barrier and went on to cause a global pandemic is HIV, the virus that causes Aids. HIV is thought to have crossed from chimpanzees to humans in West Africa in the last century and more than 25 million people worldwide have since died from it. The swine flu pandemic that emerged in Mexico last March also resulted from the mixing of viruses that infected pigs, birds and humans to create a new pandemic strain. Although it turned out to be milder than expected, future flu pandemics are expected in the coming decades that could have higher death rates and infect millions more people.

Dr Pongsiri and colleagues say that the number of people who succumbed to infectious diseases plummeted in the developed world during the industrial revolution, but the rise of manufacturing and pollution levels increased the incidence of chronic diseases including cancer, allergies and birth defects. Now, we are in the grip of another epidemiological transition 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, they say in the journal Bioscience.

David Murrell, lecturer in ecology at University College London, said: 'Since 1940, over 300 new diseases have been identified, 60 per cent of which crossed to humans from animals and 70 per cent of these came from contact with wildlife. I would expect the emergence of new diseases from contact with animals to continue in this century.'

A key factor has been increasing urbanisation, which has resulted in humans moving into previously untouched areas where they have come into closer contact with animals. At the same time, globalisation has meant newly emerged diseases have transmitted faster and more widely than in the past. 'Before the world became so interconnected, deadly and newly emerged diseases were not capable of spreading widely,' Dr Murrell said. 'Now it is very possible that they will spread across countries and continents within days, thereby sustaining the outbreak.

We don't know what's out there or how it might transmit. It is very difficult to predict. At least our government, with swine flu, is taking these things seriously now. The problem is if we deal with a threat successfully it leads to complacency. But these things are potentially serious. I would rather err on the side of caution.' "

The article can be viewed in its entirety at: http://www.independent.co.uk/news/science/deadly-animal-diseases-poised-to-infect-humans-1856777.html

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