Scientists warn of rise in diseases spread from animals to humans
Jan. 4, 2010
At least 45 such diseases have been reported to UN agencies over the past two decades and more are expected to be identified in coming years.
Experts at the US Environmental Protection Agency (EPA) in Washington claim that the world is braced for an increase in outbreaks due to global warming and changes in land use and farming practices.
Dr Montira Pongsiri, an environmental health scientist at the EPA, told the Independent: “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.”
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).
The researchers said that the number of people who succumbed to infectious diseases dropped in the developed world during the industrial revolution.
However, the rise of manufacturing and pollution levels increased the incidence of chronic diseases including cancer, allergies and birth defects.
They believe we are now experiencing another 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.
HIV is the best known example of a disease passed from animals to humans which went on to cause the global Aids pandemic. The virus 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.
David Murrell, lecturer in ecology at University College London, told the Independent: "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."
Urbanisation has been a key factor, which has resulted in humans moving into previously undeveloped areas where they have come into closer contact with animals.
Globalisation has compounded the problem because newly emerging diseases are transmitted faster and more widely than in the past.
Dr Murrell added: "Before the world became so interconnected, deadly and newly emerged diseases were not capable of spreading widely.
“Now it is very possible that they will spread across countries and continents within days, thereby sustaining the outbreak."