Experts: Human interaction behind spread of bacteria

Associated Press

WARWICK, England (AP) – People come into contact with others up to 1,000 times more frequently than they did a century ago and infectious disease experts say scientists need to better understand human behavior and movement in the global battle against germs.

Scientists gathering Monday at the annual meeting of Britain’s infectious disease trackers heard that while great strides have been made in vaccine and antibiotic development, the importance of human behavior and the way humans interact with microbes has been largely neglected.

Humans are constantly giving opportunities to microbes – viruses, bacteria, fungi and other bugs.

An example is measles, which has been recognized since at least the early 10th century. The emergence of measles in the urban centers of the great civilizations did not occur because the measles virus changed. It occurred because human behavior changed, Dr. Mike Ryan, global outbreak and response coordinator at the World Health Organization, told scientists at the conference of the Public Health Laboratory Service, Britain’s equivalent of the U.S. Centers for Disease Control and Prevention.

Overfocusing on the microbe

“We talk about the battle against infectious diseases; the war on AIDS – we have become very focused on a military approach to the microbe,” Ryan said. “The microbe must be eradicated, eliminated, beaten back. We overfocus on the microbe itself and less on the way our society behaves, the way we live and interact and how we can provide fewer opportunities for the microbe, rather than attacking it.”

But it isn’t a battle to be finished and won, Ryan said. The success of the global eradication of smallpox in 1980 gave people a false sense of hope that such success could be repeated for every disease.

“HIV has shown us that it’s a much more complicated disease than smallpox and it’s not as easy to deal with,” Ryan said. “You never win because microbes are part of nature. They will constantly emerge. If we come to terms with that and if we are smart and quick ... we’ll be ahead of them.”

The rate at which germs evolve is related to the rate of transmission of the bugs between humans, noted Dr. Roy Anderson, head of infectious disease epidemiology at Imperial College of Medicine in London.

“We understand very little about how the two are linked and about the forces that drive microbe evolution in particular settings,” Anderson said.

“Coming up in the future, in part stimulated by Sept. 11, we need to understand a lot more about people’s movements globally,” he said.

Considering world travel

While it’s clear there has been a massive increase in international travel, scientists need to know more detail, such as the rate at which people move between countries and continents and how they move around within a country, Anderson said.

One facet of modern life that offers infectious disease trackers an opportunity to gain such insight is the technology used for mobile phones, he said.

“Mobile phones are connected by networks of receivers and transmitters and an individual phone can be tracked round the United Kingdom and internationally. That’s a rich source about people’s movements,” he said. “I suspect in the coming years we are going to have the first studies of how people move and behave between particular localities.”

Anderson presented new research in which he estimated that between 1918 and 2000, physical contact between people in different countries has increased by as much as 1,000 times.

Ryan said Anderson’s research has important implications for the control of infectious diseases.

“It’s the first time I’ve heard someone quantify it. It’s quite telling,” he said. “It’s not that it makes the world a more dangerous place. It just creates more opportunities for infectious diseases to spread.”

Wednesday, September 11, 2002

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