Chapter 1: Evolution of public health security.

Chapter 1 begins by tracing some of the first steps, historically, that led to the introduction of the international health regulations (1969)--landmarks in public health starting with quarantine, a term coined in the 14th century and employed as a protection against "foreign" diseases such as plague; improvements in sanitation that were effective in controlling cholera outbreaks in the 19th century; and the advent of vaccination, which led to the eradication of smallpox and the control of many other infectious diseases in the 20th century. Understanding the history of international health cooperation--its successes and its failures--is essential in appreciating its new relevance and potential.

Throughout history, humanity has been challenged by outbreaks of infectious diseases and other health emergencies that have spread, caused death on unprecedented levels and threatened public health security (see Box 1.1). With no better solution, people's response was to remove the sick from the healthy population and wait until the epidemic ran its course.

Box 1.1 Public health security

Public health security is defined as the activities required,
both proactive and reactive, to minimize vulnerability to
acute public health events that endanger the collective
health of national populations.

Global public health security widens this definition to
include acute public health events that endanger the collective
health of populations living across geographical
regions and international boundaries. As illustrated in this
report, global health security, or lack of it, may also have
an impact on economic or political stability, trade, tourism,
access to goods and services and, if they occur repeatedly,
on demographic stability. Global public health security
embraces a wide range of complex and daunting issues,
from the international stage to the individual household,
including the health consequences of human behaviour,
weather-related events and infectious diseases, and natural
catastrophes and man-made disasters, all of which are
discussed in this report.

With time, scientific knowledge evolved, containment measures became more sophisticated and some infectious disease outbreaks were gradually brought under control with improved sanitation and the discovery of vaccines. However, microbial organisms are well-equipped to invade new territories, adapt to new ecological niches or hosts, change their virulence or modes of transmission, and develop resistance to drugs. An organism that can replicate itself a million times within a day clearly has an evolutionary advantage, with chance and surprise on its side. Therefore, no matter how experienced or refined containment measures became over the years, there was always the possibility of another outbreak causing an epidemic anytime, anywhere. The reality is that the battle to keep up with microbial evolution and adaptation will never be won.

The delicate balance between humans and microbes has been conditioned over generations of contact, exposure to immune systems and human behaviour. Today, it has shifted so that the equilibrium is driven by changes in human demographics and behaviour, economic development and land use, international travel and commerce, changing climate and ecosystems, poverty, conflict, famine and the deliberate release of infectious or chemical agents. This has heightened the risk of disease outbreaks.

It is estimated that 2.1 billion airline passengers travelled in 2006 (1). This means that diseases now have the potential to spread geographically much faster than at any time in history. An outbreak or epidemic in one part of the world is only a few hours away from becoming an imminent threat elsewhere.

Infectious diseases can not only spread faster, they appear to be emerging more quickly than ever before. Since the 1970s, new diseases have been identified at the unprecedented rate of one or more per year. There are now at least 40 diseases that were unknown a generation ago. In addition, during the last five years, WHO has verified more than 1100 epidemic events.

The lessons of history are a good starting point for this report as they exemplify the huge challenges to health that occur repeatedly and relentlessly. Some infectious diseases that have persisted for thousands of years still pose threats on a global scale.

BUILDING ON HISTORICAL LANDMARKS

Since they first walked the planet, human beings have struggled--and often failed--to protect themselves against adversaries that destroy their health, inhibit their ability to function and, ultimately, cause their death. It is only in relatively modern times that they have made lasting progress in preventing or controlling infectious diseases, as illustrated by three important historical landmarks in public health. While these advances are still of great relevance today, they need to be adapted and reinforced to confront the challenges to come.

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Plague and quarantine

The practice of separating people with disease from the healthy population is an ancient one, with both biblical and Koranic references to the isolation of lepers. By the 7th century, China had a well-established policy of detaining sailors and foreign travellers suffering from plague.

The term "quarantine" dates from the late 14th century and the isolation of people arriving from plague-infected areas to the port of Ragusa, at the time under the control of the Venetian Republic. In 1397, the period was set at 40 days (the word quarantine being derived from the Italian for "forty"). Similar actions were taken by many other Mediterranean ports soon afterwards. Such public health measures became widespread and international over the following centuries, with committees often being appointed in cities to coordinate them (2). Figure 1.1 shows the rapid spread of bubonic plague across Europe in the mid-14th century.

The continuing devastation regularly wrought by plague and other epidemic diseases demonstrated that crude quarantine measures alone were largely ineffective. In the 17th century, an attempt to keep plague, which was spreading through continental Europe, …