On March 12, 2003, while the eyes of the world were focused on the war in Iraq, the World Health Organization (WHO) issued a global alert on its website urging health workers around the world to watch out for an "atypical pneumonia" of unknown etiology which was spreading rapidly in China and Southeast Asia. On April 4, the WHO issued a global advisory warning travelers to avoid Hong Kong and China's Guangdong Province unless absolutely necessary. This was the first time in many years that the WHO had declared a specific territory off-limits.

SARS shakes the world economy

The SARS epidemic continues to spread: by mid-May infections were reported in more than 30 countries and fatalities in ten countries and territories. SARS has also shaken the world economy, causing estimated losses of US$30-150 billion. Its impact could be worse than that of the Asian recession of 1997.

The havoc wreaked by SARS has virtually closed China to international contact, raising the question of whether this crisis will endanger its position as a regional power and factory to the world. Will the Greater China economic region, comprising China, Hong Kong, Taiwan, and Singapore, be dragged down and lose much of its importance within the world economy? Which countries stand to benefit and take its place? Economic and political battle lines resulting from SARS are already being silently drawn on the international stage.

In fact, "viruses have often played a role in human history," notes anthropologist Wang Daw-hwan of the Academia Sinica's Institute of History and Philology. Jared Diamond's Guns, Germs, and Steel, which Wang translated, amply demonstrates the profound influence of biogeography on the rise and fall of human civilizations from ancient times to the present.

From the perspective of biogeography the most interesting question is why much of Africa, which boasts the longest human history, is a wilderness. Wang Daw-hwan notes that not only Africa, but the entire equatorial belt around the globe, has failed to produce a great civilization. The key to this mystery lies not in the intelligence, physical strength, or hard work of people living along the equator, but rather in the fact that they have had to fight brutal "biogeographical battles."

Dr. Wang explains that the tropics, particularly Africa's tropical forests and savannahs, are plagued by all manner of pathogenic insects and viruses. Malaria (transmitted by the mosquito), sleeping sickness (transmitted by the tsetse fly), and various tropical hemorrhagic fevers have all been obstacles to the development of Africa. Even today, despite the benefits of modern medicine and technology, they kill millions there annually.

Fighting epidemic disease

Tens of thousands of years ago our ancestors left Africa. Though they encountered numerous biological barriers as they gradually emigrated toward the tropical and temperate zones of Asia, they were still lucky: Because colder climates tend to be inhospitable to all sorts of disease-vectoring insects and microorganisms, once early humans learned to use fire, make clothing, and build houses to protect themselves from the cold, they gradually became the masters of the temperate regions.

In the more generous biological environment of the temperate regions, humanity developed agriculture and animal husbandry. This allowed a wide range of civilizations and social systems to flourish. Yet time and again humanity's supremacy was threatened by deadly hidden microorganisms: blood-sucking parasites in paddy fields, dysentery caused by water polluted with excrement, and epidemics caused by the cohabitation of people and domestic animals. With the rise of modern cities, their high population density, particularly in slums, as well as cross-territorial trade, were everywhere hotbeds for the spread of infectious diseases.

In Europe, the Antonine plague of 165, which was probably caused by an early form of smallpox, ravaged Rome for 15 years. The Justinian Plague of 542 was the origin of the Black Death (or bubonic plague). After lying completely dormant for centuries, the Black Death staged a comeback in the mid-fourteenth century, decimating much of Europe. An estimated 20 million people, or a third of Europe's population, were killed, prosperous cities were laid in ruins, and the course of European civilization was altered.

Smallpox threatens the world

During the protracted war with microorganisms, a series of epidemics-smallpox, bubonic plague, syphilis, typhoid, and tuberculosis-struck Europe, India, and China, steadily increasing the natural resistance to these diseases among Eurasian populations. In the sixteenth century, Hernan Cortes and 600 conquistadores set out from the coast of Yucatan to the Mexican interior to conquer the Aztec empire and its population of several million. Surprisingly, Cortes achieved victory not due to superior weaponry, nor by God's favor, but thanks to a secret weapon that came unannounced: smallpox.

When smallpox struck the Aztec empire, the indigenous population had no resistance to infection from the virus, and was consequently decimated by it. Smallpox wiped out half the empire; even the Aztec ruler Cuitlahuac succumbed to the disease. The population of the area that is today Mexico, which numbered 20 million before the European arrival, had fallen to 1.6 million only 100 years later.

The Peruvian Inca empire suffered a similarly tragic fate, as did most North American indigenous nations. Indeed, it is said that European settlers in the American West deliberately presented smallpox infested blankets to Native Americans. But why was smallpox such a deadly weapon?

The causes can be traced to the isolation of North American plant and animal life, to a large indigenous population, and to geographical barriers to population exchanges. These factors for thousands of years prevented indigenous peoples from building up resistance to viral diseases and left them exceedingly vulnerable to them.

Even more tragic was the fact that because the epidemics had been introduced from Europe, the indigenous peoples of the Americas, who were the only ones affected by them, considered them to be heaven's wrath. Believing that their gods and customs provided no protection, they rejected their traditions. America's glorious ancient civilizations were thus completely annihilated.

Flu: the great killer

In the mid-nineteenth century, the French doctor Louis Pasteur discovered bacteria as well as vaccines against rabies and other viral infectious diseases. The dark veil of mystery covering infectious disease was lifted for the first time in history. But it was not until the invention of the electron microscope that humanity discovered that many of these infectious diseases were caused by smaller and deadlier germs: viruses.

In 1918, toward the end of World War I, the Spanish flu swept the world, infecting an estimated 20% of the world's population. Military units dispatched across continents and cramped together in unsanitary living conditions provided ideal conditions for the spread of influenza. A great many also perished in the cities, where electric trams were used to clear away the corpses.

It was subsequently estimated that the Spanish flu of 1918 killed between 20 and 100 million people around the world, including 500,000 in the United States alone, decreasing the average life expectancy by 12 years in one year! This pandemic was the deadliest in mankind's long history of war with microorganisms.

The discovery of penicillin, the world's first antibiotic, in 1930, greatly reduced the threat of bacterial infection. To date, medical science has discovered more than 150 antibiotics to combat a huge range of bacterial infections.

Antiviral drugs are still not particularly effective. But the widespread use of vaccines and advances in vaccinology have effectively brought smallpox, poliomyelitis, and other viral diseases under control. Now that even influenza can be inoculated against, humanity faces a significantly reduced threat from viral disease.

Thus by the second half of the twentieth century, thanks to an apparently invincible medical science, humanity seemed to have become the absolute master of the natural world. So much so, that it began to let down its guard against viral disease-until 1981.

AIDS convulses the world

"The discovery of AIDS in 1981 opened a new chapter in humanity's struggle with microorganisms," says Chen Hour-young of the Department of Health's Center for Disease Control, who has researched the history of microorganisms in depth. Based on the present state of knowledge, the HIV virus displays the most mutations of any virus and is also the most harmful to humans. In 1997 alone, 11.7 million people died of AIDS, more than the total number of casualties in World War I.

Since then, thanks to the drug cocktail treatment pioneered by Dr. David Ho and the joint efforts of the global medical community, as well as the general acceptance of concepts of safe sex, the AIDS mortality rate has declined. Last year, an estimated 3 million people around the world died of this disease.

In view of the extraordinary persistence of AIDS, the medical world began to wake up to the fact that viral diseases were staging a major counteroffensive. In 1995 the WHO warned that there was a trend of new strains of bacteria and viruses that were rapidly mutating into new infectious diseases as well as re-emerging infectious diseases that had long been eradicated or brought under control.

In 1976, Ebola fever broke out in Central Africa. The following year, Legionnaires Disease erupted in the United States. Four years later, AIDS appeared on the stage. Then came mad cow disease, new strains of cholera, the Hong Kong avian flu, and a host of other infectious diseases. And now SARS! Reviewing the long list of new infectious diseases, Chen Hour-young's demeanor turns grave. He says that both new disease strains and old diseases that develop new clinical symptoms represent a new battlefront. To put it in a nutshell: While mankind was intoxicated with the illusion that it had conquered infectious disease, armies of microorganisms had reorganized and were preparing the next wave of attack.

Nature's counterattack

Why has nature launched a counterattack? The medical world has identified dozens of causes, all of which involve huge corporate interests and are inextricably connected to modern lifestyles. Put simply, says Chen Hour-young, "Mankind considers itself all-powerful and the center of all things. It also thinks that all living creatures are to be conquered for its own use. By our lust for profit and comfort we end up harming ourselves."

Most striking of all is humanity's ever-expanding sphere of activity: We clear forests, drain marshes, and upset the ecological balance of nature, forcing wild animals and microorganisms to flee from their once well-hidden habitats into the open. In the struggle for survival, they inevitably encroach on humanity's territory. The Malaysian encephalitis outbreak of 1998, caused by the Nipah virus, was a classic case in point.

In the pursuit of industrial development, mankind has released countless toxic substances into the atmosphere, causing global warming and abnormal climate change. As a result of the greenhouse effect, microorganisms that used to thrive in the tropics are now capable of survival in temperate regions. Contagious diseases that previously only existed in the tropics, such as dengue fever, malaria, and many others, are posing a growing threat to the populations of temperate regions.

The relentless pursuit of economic efficiency and the development of new products also provides new opportunities for microorganisms. Many respiratory-tract infectious diseases, including Legionnaires Disease and SARS, spread quickly through closed air-conditioning systems; extended-wear contact lenses are ideal breeding grounds for bacterial conjunctivitis; in many cosmetic products there are bovine collagens containing mad cow disease proteins; and "airport malaria" circles the globe on airliners.

What probably most worries the medical community is the overuse of antibiotics both in humans and animals, which has led to a wide range of resistant bacteria strains. "Super-bugs" are resistant to all known antibiotics. The reemergence of tuberculosis around the world in recent years has caused a sharp rise in deaths from this disease.

While there is still debate over the exact origin of SARS, it may have come from the raising together of different types of animals in the Guangdong region of China, allowing heretofore separate animal viruses to exchange genes and create a killer. Whatever its origin, in any case there is no doubt that its spread is intimately related to the modern lifestyle of dense, mobile populations living in economically developed areas.

Harmony, not opposition

The growth of new epidemics and reemerging infectious diseases has prompted the medical community to reexamine the relationship between humanity and microorganisms. In fact, behind the veneer of invincibility, medical science is always apprehensive. Chen Hour-young stresses that in its war with microorganisms, humanity has always had the disadvantage of fighting an invisible enemy. Many infectious diseases come and go like the wind, leaving behind a host of intractable questions. The Spanish flu of 1918, for example, swept the world for a year and a half and then suddenly disappeared without a trace. Although epidemiologists from around the world spent many decades searching for this deadly virus and monitoring possible outbreaks, they failed utterly to find the key to its origin in 1918.

Today we can perhaps say that thanks to rigorous public health measures and anti-epidemic systems, as well as the collaboration of the global medical community, even the deadliest microorganisms no longer threaten to swiftly kill huge numbers of people around the world. Nonetheless, given that in the war between people and microorganisms there can only be two perpetual losers, what's more important is for humanity to learn some humility, give up its crazy notion that it can be the master of all creation, and allow all living beings, including microorganisms, to enjoy their natural habitats undisturbed by man.

Chen Chien-jen, member of the Academia Sinica and head of the Department of Health, notes that the statement made by the American virologist C.J. Peters in his book Virus Hunter: Thirty Years of Battling Hot Viruses Around the World-"live in harmony with yourself, with others, and with nature"-ought to be the guiding principle of coexistence between mankind and microorganisms. Because it is better to make friends than enemies, humanity will have to take the first step.

p.23

In 1918, during the Japanese Colonial Era, Taiwan too was ravaged by the Spanish flu. To stop its spread, the Japanese authorities set up quarantine stations at every ferry crossing. (courtesy of the National Central Library's Taiwan division)

p.24

During the turmoil surrounding the resumption of Chinese rule in Taiwan after WWII, the island was plagued by all sorts of parasites and infectious diseases. Foreign medical and charitable organizations provided much timely assistance.(courtesy of the Center for Disease Control's Kunyang St. branch)

p.25

Remember how when you were a kid everyone bought anti-tuberculosis stamps? In those days, tuberculosis was the main target in Taiwan's fight against infectious disease-with remarkable results. But the medical community is very concerned about the reemergence of the TB bacillus in recent years.(photo by Vincent Chang)

p.26

In recent years poultry and domestic animals have been slaughtered in large numbers to prevent rabies, hoof-and-mouth disease, avian flu and other infectious diseases caused by contact between people and animals. The photograph shows the slaughter of a bull by order of Kinmen authorities during a 1999 outbreak of hoof-and-mouth disease. (photo by Li Mu-lung)

p.27

Sidewalk food stalls can harbor the deadly hepatitis B virus, while spitting on the street can transmit the SARS virus. An unsanitary environment and living habits are weak points in the public health system. (photo by Pu Hua-chih)

p.29

Pollution, high-rise buildings, cramped living conditions, and the hustle and bustle of city life make it extremely difficult to track down and monitor infectious disease outbreaks. (photo by Pu Hua-chih)

During the turmoil surrounding the resumption of Chinese rule in Taiwan after WWII, the island was plagued by all sorts of parasites and infectious diseases. Foreign medical and charitable organizations provided much timely assistance.

Sidewalk food stalls can harbor the deadly hepatitis B virus, while spitting on the street can transmit the SARS virus. An unsanitary environment and living habits are weak points in the public health system.

Pollution, high-rise buildings, cramped living conditions, and the hustle and bustle of city life make it extremely difficult to track down and monitor infectious disease outbreaks.

Remember how when you were a kid everyone bought anti-tuberculosis stamps? In those days, tuberculosis was the main target in Taiwan's fight against infectious disease-with remarkable results. But the medical community is very concerned about the reemergence of the TB bacillus in recent years.