Diseases Travel Fast, but So Do Tools to Fight Them

By Kevin Sullivan and Mary Jordan
Washington Post Foreign Service
Wednesday, April 29, 2009

LONDON, April 28 -- Teenagers in New Zealand, honeymooners in Scotland, high-schoolers in New York and tourists in Israel all are sick from the same bug caught just days ago on trips to Mexico.

Their illnesses are the latest example of how diseases, from influenza to tuberculosis to cholera, are spreading ever more quickly in an increasingly globalized world. But so, too, are the tools necessary to combat outbreaks of disease: expertise, medicine, money and information.

"Things move incredibly fast; there has been an exponential rise in the numbers of people who move around the world," said Scott Dowell, a physician and head of global disease detection and response for the U.S. Centers for Disease Control and Prevention in Atlanta.

Although global pandemics are as old as history itself, diseases and the people who carry them have never been able to move so far, so fast. The number of international air travelers grew fivefold, to 824 million passengers per year, from 1980 to 2007.

Spanish explorer Hernán Cortés transported smallpox and measles to Mexico on long sea voyages in the 16th century. The current strain of swine flu leapt from Mexico to the far corners of the world on jumbo jets in a matter of hours.

"That makes it incredibly harder to manage these outbreaks," said Dowell, who is overseeing the CDC's assistance to Mexico on the swine flu case. In New Zealand, for example, officials were trying to track down all 350-plus passengers who were on the same flight as the infected high-schoolers (Air New Zealand Flight 1 from Los Angeles to Auckland on April 25).

Although the world is more vulnerable to the rapid spread of disease, many experts say, it has never been more prepared.

Advances in the understanding of disease, stockpiling of vaccines and global networks of medical surveillance have better equipped health professionals to deal with outbreaks. Instant communications have allowed information on diseases to move faster than the bugs themselves. The swine flu page on the CDC's Web site lets users sign up for e-mail alerts, podcasts and news feeds; more than 36,000 people have signed up for CDC Twitter alerts.

"It's a very different world than it was even 10 years ago," said Robert F. Breiman, a physician and coordinator of the CDC's Global Disease Detection Division center in Nairobi.

The Nairobi center is one of six maintained by the CDC around the world; the others are in Egypt, Thailand, Kazakhstan, China and Guatemala. In each, CDC medical professionals work with local officials to detect disease outbreaks in the region and coordinate their responses.

The centers were established in the wake of the 2003 outbreak of severe acute respiratory syndrome, or SARS, which caused hundreds of deaths around the world.

Dowell said that five CDC staffers, including infectious-disease specialists from the Guatemala office, are in Mexico, and that six more are likely to head there soon.

The CDC also works with the World Health Organization's Global Outbreak Alert and Response Network, which coordinates efforts among health officials around the globe.

"There is no such thing as a local outbreak," Michael Ryan, a physician who runs the WHO's global outbreak program, said in an interview before the epidemic in Mexico.

A report issued by a committee in the British House of Lords last year concluded that dramatic global population growth was a key factor in spreading infectious disease.

It said the world's population has risen from 2.5 billion in 1950 to more than 6 billion now and is projected to rise to 9 billion by 2050. And the population is growing fastest in many of the poorest countries with the biggest health problems.

Mass migrations have turned such places as Lagos, Nigeria, and Rio de Janeiro into megacities where overcrowding and poverty create ideal conditions for the spread of diseases such as dengue fever. An outbreak in Brazil killed at least 100 people last year.

Several thousand Bolivians have immigrated to Switzerland in recent years, and with them has come Chagas disease, a parasitic illness that can cause heart problems. Chagas, once confined to rural Latin America, also has spread with migrants to the United States and Asia.

The British report noted that rising populations are forcing people to push deeper into previously uninhabited land to live and grow crops. Going deeper into jungles and forests has led to closer contact with wild animals, which can carry new pathogens that lead to previously unknown illnesses, the report said.

Such contact with animals, particularly primates, has often been documented in African outbreaks of Ebola, the acute hemorrhagic fever.

Climate change is creating droughts and floods where they were not common before, and that is also altering patterns and flows of disease. In warming temperatures, mosquitoes are migrating to new areas, carrying diseases once confined to the tropics.

Chikungunya, a tropical disease from Africa and Asia that causes severe joint pain, showed up in Italy in 2006 and has infected several hundred people there. A tourist who visited Kerala, India, is suspected to have carried the virus home. Then the Asian tiger mosquito, which is working its way north as temperatures rise, carried it from one infected person to the next.

Robin Weiss, a British virologist who has written about the globalization of disease, said instant global communication can rapidly spread helpful information, but it can also have downsides, such as needlessly alarming people with a flood of texts, e-mails and news bulletins.

"There are good and bad effects of globalization" on infectious disease, said Mario Raviglione, a top tuberculosis official at the WHO in Geneva.

Raviglione said the globalized economy means that money flows to poorer countries to help them improve health systems and fight high-profile diseases such as HIV/AIDS. But when the banking system falters in one country and drags down financial systems around the globe, that has a direct effect on how much families and governments can spend on fighting disease.

"We all live in a global village," Raviglione said.

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