Rarely a day goes by without at least one article on the threat of the avian influenza in Asia becoming pandemic. If a pandemic of the magnitude projected by the World Health Organization does occur, it will cause a global emergency that will make all others pale by comparison, both in terms of public health and economic impact. We should therefore, take notice and get prepared.

Why are health authorities concerned about a pandemic of avian influenza? Because all indications are that history may repeat itself. Influenza has caused three pandemics in the past 100 years, in 1918, 1957 and 1968. The 1918 pandemic was among the worst health-related disasters in the history of mankind, on a par with the Black Death of Europe in the mid-14th century that was caused by bubonic plague. It is estimated that globally, 40 million to 50 million people died in the 1918 influenza pandemic; in the U.S., the estimates were 500,000 excess deaths (see chart). The 1957 and 1968 pandemics were smaller, each with an estimated 1 million to 4 million deaths globally.

Scientists have been uncertain about the traits of the influenza virus that caused such devastation in 1918, but recent work with viral genome recovered from human tissues preserved from that epidemic have shown that it was caused by a strain of avian influenza virus that apparently developed the ability to efficiently transmit from person to person.

Influenza viruses are natural pathogens of birds but are capable of changing genetically to allow infection of other animals, including humans. A major concern for health authorities is that a new strain of virus will emerge with an increased ability to infect and be transmitted between humans.

The H5N1 strain of avian influenza that is of current concern was first identified in Southeast Asia in 2003. In two short years, the virus has spread throughout that region, infecting both commercial chicken flocks and other domestic birds such as geese and ducks, which are widespread in rural areas of Asia. Attempts to control the spread by culling flocks have failed; there has been no vaccine available. In recent months, this H5N1 virus has spread to Europe, apparently via migrating birds.

To date, there have been 117 human cases and 60 deaths (a 51 percent fatality rate), all of them in Asian countries and most as the result of handling infected birds. Although the virus has a high mortality rate in humans, it has not yet mutated nor reassorted genetically to allow efficient human-to-human transmission. Scientists are working on the reconstructed 1918 influenza virus in an attempt to identify the genetic changes responsible for that virus being so virulent and so efficiently transmitted between humans.

Modern transportation and globalization is a major concern in 2005. The jet airplane provides the ideal mechanism to transport humans and animals, along with their pathogens, between population centers of the world. In contrast to 1918, when it took days to weeks to travel between regions and continents via ship, in 2005 it takes only a few hours to make the same journey. In addition, the numbers of people making these journeys in 2005 are an order of magnitude or larger, with tens of millions of people flying between continents and regions annually. The risk of importing an exotic pathogen like avian influenza, therefore, is at the highest level in history.

What does this mean for Hawai'i, strategically located in the middle of the Pacific? In 2005, Hawai'i will receive approximately 7 million visitors, with an estimated 2 million coming from Asia. A recent study published in the Proceedings of the National Academy of Sciences has identified Honolulu as one of 25 central cities in the global air traffic network. This means Hawai'i is highly vulnerable to importation of exotic pathogens and will be at high risk for the importation of avian influenza should a pandemic occur.

Is Hawai'i prepared for the introduction of avian influenza or another exotic pathogen that can cause a major epidemic? We will never be as prepared as we would like, but the state Department of Health has been working feverishly to develop a contingency plan for such an event. Part of this plan is to develop more effective disease detection systems that identify unusual disease activity without delay after it is introduced, and emergency response plans that can mitigate the impact of the epidemic before it reaches peak transmission.

This early-warning disease detection and response system requires a research diagnostic laboratory that can quickly and accurately identify the pathogen causing the unusual disease activity. The Asia-Pacific Institute of Tropical Medicine and Infectious Diseases, John A. Burns School of Medicine, University of Hawai'i, in partnership with the state Department of Health, Department of Defense and Hawai'i Biotech has recently received a $25 million grant from the National Institute of Health to build a regional biosafety laboratory in Hawai'i. A $12.5 million match is required from the state. This laboratory will provide desperately needed support for the above disease detection and response system. It must be remembered, however, that even the best early-warning system cannot protect the people of Hawai'i unless an effective emergency response plan is implemented without delay after the unusual disease activity is identified.

Residents of Hawai'i can help health authorities by being alert to any unusual illness in their community and reporting it to the state Department of Health. They also should practice good hygiene, including regular hand-washing, avoiding the touching of eyes, nose or mouth, avoiding close contact with people who are sick and staying home when sick.

Duane J. Gubler is director of the Asia-Pacific Institute for Tropical Medicine and Infectious Diseases and chairman of the Department of Tropical Medicine and Medical Microbiology at the John A. Burns School of Medicine. He wrote this commentary for The Advertiser.