Global Public Health Threats

2. What steps were taken to contain disease outbreaks in the past?

• 2.1 How effective was quarantine against the plague?
• 2.2 How can sanitation prevent the spread of cholera?
• 2.3 How was smallpox eradicated and why is it still a threat?
• 2.4 Why were International Health Regulations established and strengthened?

Throughout history, humans have struggled to protect themselves against illnesses that have spread and caused death at unprecedented scales.

Until relatively recent times, the only way to control the spread of infectious diseases was to separate the sick from the healthy population. It is only since the 19^th and 20^th centuries, that advances in scientific knowledge have made it possible to contain some outbreaks with improved sanitation and the discovery of vaccines.

Microbes reproduce and adapt quickly. They can change the way they pass from one person to another and become resistant to drugs. Human behavior has also changed and with increased air travel and commerce, changing climate, wars, poverty and famine, the risk of disease outbreaks has increased.

Today, not only can infectious diseases spread faster, but they appear to be emerging more quickly than ever before. So although current methods of disease control are effective, they need to be adapted and reinforced to face the challenges to come.

This text is a summary of: WHO, World Health Report 2007 – A safer future: global public health security in the 21^st century (2007),
Chapter 1: Evolution of Public Health Security, p.1-2 

2.1 How effective was quarantine against the plague?

Since ancient times, various civilizations have tried to contain the spread of infectious diseases by isolating the sick from the healthy.

In the 14^th century, the authorities in many Mediterranean ports isolated (quarantined) people arriving from plague-infested areas for at least 40 days. The incomers were only allowed to mix with the rest of the population if they showed no sign of disease in that time. Such public health measures became widespread during the following centuries.

However, the crude quarantine measures in place during the Middle Ages were ineffective against some diseases such as the bubonic plague which is usually transmitted by infected fleas carried by rats. A devastating outbreak of plague swept though Europe in the 14^th century, killing millions. There were regular outbreaks of the disease until the 17th century and one of these outbreaks decimated England in 1665 and 1666 despite quarantine measures that forced all ships to wait for forty days at the mouth of the river Thames

In recent years, the most serious outbreak of plague occurred in 1994 in five states in India. It was under control within 2 months, but had catastrophic economic consequences with an estimated cost of approximately US$ 1.7 billion in lost trade and tourism. Since then, there have been a number of smaller outbreaks of the bubonic plague in countries such as Algeria, the Democratic Republic of the Congo, Malawi and Zambia.

This text is a summary of: WHO, World Health Report 2007 – A safer future: global public health security in the 21^st century (2007),
Chapter 1: Evolution of Public Health Security, "Plague and quarantine", p.2-3 

2.2 How can sanitation prevent the spread of cholera?

Until the 19^th century, it was not known how cholera was transmitted. Scientists at the time believed that it spread through poisonous vapours but in the 1850s John Snow, a British doctor, showed that cholera was transmitted through contaminated water. His work eventually led to improvements in sanitation in the United Kingdom that reduced the threat of the disease.

Nonetheless, cholera continues to be a major health risk all over the world.

Latin America had been free of cholera for over a century until 1991, when boats with cholera-infested bilge water contaminated seafood off the coast of Peru. The disease spread rapidly across the continent with devastating human and economic consequences, infecting more than 1 million people and causing over 10 000 deaths in 16 countries by 1995. In addition to human suffering and death, the outbreak provoked panic, disrupted social and economic structures, and cost the region as much as US$ 1.5 billion.

The need to ensure safe water and hygiene remains a huge challenge today in developing countries. Currently 1.1 billion people have no access to safe drinking water and 2.6 billion people lack access to proper sanitation. As a result, many people die from easily preventable diseases and suffer from poor health, weakened productivity and missed opportunities for education.

This text is a summary of: WHO, World Health Report 2007 – A safer future: global public health security in the 21^st century (2007),
Chapter 1: Evolution of Public Health Security, "Cholera and sanitation", p.4 

2.3 How was smallpox eradicated and why is it still a threat?

Smallpox is one of the oldest and deadliest known human diseases. In the 18^th century, Edward Jenner discovered a vaccine for smallpox, but at the beginning of the 20th century it was still present in almost all countries of the world. In the early 1950s, an estimated 50 million cases occurred globally each year leading to approximately 15 million deaths. In 1967, a world-wide 10-year campaign of vaccinations began. The programme was very successful: the number of cases of smallpox and the deaths caused by the disease dropped rapidly to about one fifth, and by 1979 smallpox was eradicated.

Almost 30 years after its successful eradication, smallpox is once again a significant public health concern as some countries and terrorist groups are accused of storing the smallpox virus for deliberate release. If an outbreak is not controlled quickly, smallpox could again become endemic and this would undo one of the greatest achievements in terms of public health. This potential bioterrorist threat is causing major concern in many industrialized countries and work is under way on a new and safer vaccine.

This text is a summary of: WHO, World Health Report 2007 – A safer future: global public health security in the 21^st century (2007),
Chapter 1: Evolution of Public Health Security, "Smallpox and immunization", p.5-6 

2.4 Why were International Health Regulations established and strengthened?

Responding to the need for international coordination of public health strategies, the World Health Organization (WHO) was created in 1948. In order to contain diseases through control measures at international borders, the International Health Regulations (IHR) were adopted in 1969 .

In the globalized world of the 21^st century, borders alone cannot stop the international spread of diseases. With increased air-travel and trade, an outbreak or epidemic in any part of the world is only a few hours away from becoming a threat somewhere else. Another challenge when coping with public health threats is the spread of panic through instantaneous modes of communication, such as mobile telephones and the internet.

Responding to these new global challenges, Member States of the United Nations (UN) agreed on a new set of regulations, which came into force in June 2007. The focus of the 2005 International Health Regulations is not to control diseases at borders but to quickly tackle any outbreak at its source.

The 2005 International Health Regulations address public health threats such as infectious diseases, as well as the accidental or intentional release of chemicals, radioactive materials and of any microorganism that may cause health effects and sickness.

The WHO responds to incidents reported by official sources or which are detected by its own networks.

Examples of such networks are GOARN and ChemiNet.

• The Global Outbreak Alert and Response Network (GOARN) can quickly identify and respond to disease outbreaks of international importance. Even in extreme environments, systems have been established to stockpile and distribute vaccines, drugs and special equipment to deal with haemorrhagic fevers, influenza, meningitis, smallpox and yellow fever. In addition, GOARN surveys many other vaccine-preventable diseases. The Organization continues to strengthen specialized surveillance networks for dangerous microorganisms that can cause disease, including dengue, influenza and plague.
• The Chemical Incident Alert and Response System was established by the WHO to detect and respond to chemical incidents and other environmental health emergencies, including those related to the disruption of environmental health services, such as water supply and sanitation, as well as radiological events. An integral part of the system is ChemiNet, which pools human and technical resources for detecting, verifying and responding to environmental health events, which might be of international public health concern.

Thanks to the spectacular advances in medicine and public health during the first half of the 20^th century it is now possible to prevent, control or treat most infectious diseases. However, world wide epidemics, referred to as pandemics, are still likely. They represent a huge threat to public health security, for two main reasons: firstly, some infectious diseases continue to thrive in developing countries and could spread internationally at great speed, and secondly, some microbes that infect animals are crossing the species barrier. They become infectious to humans resulting in the emergence of new diseases for human populations which could spread internationally. Therefore, international measures to prevent the spread of infectious diseases are still essential in the 21^st century.

This text is a summary of: WHO, World Health Report 2007 – A safer future: global public health security in the 21^st century (2007),
Chapter 1: Evolution of Public Health Security, "Fostering international cooperation", p.6-14