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Global Public Health Threats

3. How is human behavior undermining collective health?

  • 3.1 What can be the consequences of a false sense of security?
  • 3.2 How can armed conflict weaken health systems?
  • 3.3 Why is antibiotic resistance a growing concern?
  • 3.4 How can rearing animals lead to disease transmission?
  • 3.5 How can changes in climatic conditions threaten public health?
  • 3.6 What are the consequences of disasters like Chernobyl or Bhopal?

The behavior of individuals at all levels – political leaders, policy-makers, military commanders, public health specialists and the general population – can have major health consequences, both negative and positive.

Threats to public health security such as natural disasters, epidemics of infectious diseases, chemical and radioactive emergencies or other health events, can have one or more causes. The causes may be natural or man-made, environmental or industrial, accidental or deliberate, and in many cases related to human behaviour.

Public health is undermined not only by human action but also by the lack thereof. For instance, complacency and a false sense of security can tempt governments to reduce spending on public health and to scale down prevention programmes - with potentially disastrous consequences for collective health.

This text is a summary of: WHO, World Health Report 2007 – A safer future: global public health security in the 21st century (2007),
Chapter 2: Threats to Public Health Security, p.17 

3.1 What can be the consequences of a false sense of security?

Times when there are no outbreaks of infectious diseases can give rise to a false sense of security and inadequate investment in public health. For example, as a result of large-scale insecticide spraying campaigns, by the late 1960s most of the important diseases carried by insects were largely under control. They were considered to remain a problem only in sub-Saharan Africa and control programmes were discontinued. However, within 20 years many of these diseases carried by insects emerged in new areas or re-emerged in areas previously affected.

Urbanization, increasing international trade and travel have contributed to the rapid spread of viruses and insects that carry them. For instance, dengue caused an unprecedented pandemic in 1998, with 1.2 million cases reported to the WHO in 56 countries. Since then, dengue epidemics have continued and have affected millions of people from Latin America to South-East Asia. Globally, the average annual number of cases reported to WHO has nearly doubled in each of the last four decades.

Surveillance is crucial for public health security and without it, it is impossible to detect and respond to emerging health threats. For instance, HIV/AIDS had perhaps been occurring for many years in Africa and Haiti but had not been detected due to inadequate surveillance and health systems in these developing countries. This new disease was only brought to international attention when the first few cases appeared in the United States. Even then, the disease was not detected by surveillance systems but by chance, when epidemiologists noticed an unusual number of orders for drugs to treat a rare infection that is common in AIDS cases.

Early efforts to control the AIDS epidemic were hampered by a lack of proper data on sexual behaviour and sexually transmitted diseases, whether in Africa, Haiti, the United States or other industrialized countries. In the industrialized world, information was out of date by the time AIDS appeared as a major public health threat, and in the developing world it was non-existent. Even today, the poor understanding of HIV/AIDS in the context of sexuality in the developing world raises problems.

Even with effective surveillance and prevention programmes in place, unexpected policy changes in public health systems can have deadly and costly repercussions. For example, the Nigerian government suspended polio vaccinations in parts of its territory in 2003 because of unfounded claims that the vaccines were unsafe. Following this decision, there was a large outbreak of poliomyelitis across northern Nigeria that paralyzed thousands of children and spread to 19 polio-free countries in Africa, Asia and the Middle East. The response to the outbreak across these countries cost more than US$ 450 million. In July 2004, polio immunization started again throughout northern Nigeria, as a result of a tremendous collaborative effort between Nigerian authorities and traditional and religious leaders, supported by the African Union, the Organization of the Islamic Conference and others.

This text is a summary of: WHO, World Health Report 2007 – A safer future: global public health security in the 21st century (2007),
Chapter 2: Threats to Public Health Security, "Inadequate inversment" and "Unexpected policy changes" p.18-21 

3.2 How can armed conflict weaken health systems?

Some 50 000 Rwandan refugees died of cholera in a crowded
                                        camp in 1994
Some 50 000 Rwandan refugees died of cholera in a crowded camp in 1994

Wars and other armed conflicts often result in the destruction or weakening of health systems, leaving them less able to detect, prevent and respond to infectious disease outbreaks. For instance, the 27-year civil war (1975–2002) in Angola left the country with a severely damaged health infrastructure. As a result, the country was incapable to control the outbreak and spread of the Marburg haemorrhagic fever in 2004–2005, which killed 90% of the 200 people affected. The Angolan authorities, with the support of the international community, launched a massive effort to rebuild its infrastructure, but despite their best attempts, 70% of the population is still without basic health care.

Wars, conflicts and natural catastrophes often force large numbers of people to migrate to other countries. These people often have to live in crowded, unhygienic and poor conditions, which, in turn, increase the risk of infectious disease epidemics. Such conditions were the cause of the cholera epidemic in the Democratic Republic of the Congo, in the aftermath of the crisis in Rwanda in 1994. In July of that year, between 500 000 and 800 000 people crossed the border to seek refuge in the outskirts of the city of Goma. The only source of water available to them was a lake that was contaminated with the cholera virus, and they did not have proper housing and sanitation. The resulting outbreak of combined cholera and shigella dysentery killed nearly 50 000 refugees within one month of their arrival.

The problems associated with people living in crowded environments also arise in cities, which are now home to over half the world’s population. Rapid and uncontrolled urbanization is characterized by the growth of informal settlements such as slums. More than one third of those who live in cities – one billion people – dwell in cramped conditions, without access to safe water, sanitation, safe food, decent shelter or meaningful employment.

This text is a summary of: WHO, World Health Report 2007 – A safer future: global public health security in the 21st century (2007),
Chapter 2: Threats to Public Health Security, "Public health consequences of conflict" p.21-22 

3.3 Why is antibiotic resistance a growing concern?

Antibiotics are widely used as medication against disease-causing bacteria. However, some strains of bacteria are resistant to particular antibiotics and others can acquire resistance through genetic changes. The widespread use of penicillin and other antibiotics since 1942 has brought about great advances in public health, but with an unfortunate side-effect: a growing number of varieties of bacteria, including some causing tuberculosis, are now resistant to antibiotics and other drugs.

The selection and spread of these varieties are facilitated by improper use of antibiotics, for instance:

  • over-prescription of drugs
  • insufficient prescription of drugs,
  • patients not taking the recommended doses,
  • unregulated sale by non-health workers and
  • treatment of diseases in plants and animals with the same antibiotics that are used to treat humans.

Besides bacteria, also parasites and viruses develop resistance to drugs, which makes the treatment of diseases such as malaria and HIV/AIDS increasingly difficult.

Many organisms are resistant to several drugs. This makes antibiotic-resistant infections more expensive to treat and more likely to cause the death of the patient. In addition, fewer new antibiotics are reaching the market and it is unlikely that a new antibiotic treating a wide range of illnesses will appear soon. However, new drugs are being developed for diseases such as tuberculosis and malaria.

The spread of drug resistance worldwide is one reason why it is so important to detect and respond to outbreaks of infectious diseases as quickly as possible, to strengthen health systems and communications, improve water and sanitation, and reduce changes in the environment. It is also crucial to use drugs appropriately so that the strains of organisms that become more common are those that can be treated with existing drugs.

This text is a summary of: WHO, World Health Report 2007 – A safer future: global public health security in the 21st century (2007),
Chapter 2: Threats to Public Health Security, "Microbial evolution and antibiotic resistance", p.22-23 

3.4 How can rearing animals lead to disease transmission?

Feeding and rearing animals under improper conditions can have serious health consequences. For instance, starting in the United Kingdom in the 1980s, processed cattle meat was fed to cows. Cattle carcasses infected with bovine spongiforming encephalopathy (BSE) were also added to livestock feed and this led to an epidemic commonly called “mad cow disease” that had immense economic consequences for the United Kingdom. The epidemic in cows soon became of concern to human health as cases of variant Creutzfeldt-Jakob disease, a human form of “mad cow disease”, begun to emerge mainly in the United Kingdom, but also in other countries in Europe and America. The most likely cause of variant Creutzfeldt-Jakob disease was eating contaminated meat. Some people have developed the disease after receiving transfusions of contaminated blood.

The emergence of new organisms that cause diseases has serious public health consequences. For example, between September 1998 and April 1999 there was an outbreak in Malaysia of a new disease caused by the Nipah virus, a previously unknown virus that causes an inflammation of the brain, and which kills up to 75% of the people that it infects. Initially there was some confusion as to the cause of the disease, which delayed the effective treatment and control measures. Eventually it was recognized that the disease was transmitted among pigs and then from pigs to humans. The outbreak ended once more than 1 million pigs were killed. There is some evidence that since 1999, the virus may have become more harmful for humans: people who are not in contact with pigs can now get it, and it can spread easily from human-to-human, especially in medical facilities. This makes the disease more difficult to control as killing pigs alone is no longer effective for containing an outbreak. Moreover, fruit bats infected with Nipah have now been found in various countries.

This text is a summary of: WHO, World Health Report 2007 – A safer future: global public health security in the 21st century (2007),
Chapter 2: Threats to Public Health Security, "Animal husbandry and food processing", p.24-25 

3.5 How can changes in climatic conditions threaten public health?

Climate change, especially the increase of extreme weather events, together with other environmental and social factors, is changing the exposure of populations to infectious diseases. In such rapidly changing conditions, prevention is of the greatest importance; where prevention has failed, identifying and responding to epidemics becomes even more important.

For example, in 1997 there was a higher than average rainfall in East Africa, in combination with the warm phase of El Niño, which increased the breeding sites of mosquitoes. This resulted in a large outbreak of the Rift Valley fever, a disease that has serious complications for humans and can cause death. The disease spreads easily as it is transmitted to animals as well as humans, and female mosquitoes can pass on the infection to their offspring. To prevent epidemics, animals have to be vaccinated before an outbreak starts. After the 1997–1998 outbreaks, a system was put in place that uses satellite images and weather forecasts to predict outbreaks of the Rift Valley fever. Animals can then be vaccinated before the onset of an outbreak in order to prevent an epidemic. The same method may be useful for predicting outbreaks of other viruses such as the ones causing dengue, West Nile fever and yellow fever.

This text is a summary of: WHO, World Health Report 2007 – A safer future: global public health security in the 21st century (2007),
Chapter 2: Threats to Public Health Security, "Weather-related events and infectious diseases", p.25-26 

3.6 What are the consequences of disasters like Chernobyl or Bhopal?

Reliance on chemical processing and nuclear energy calls for public health security measures. Facilities and their products are a potential danger to public health because there is always the possibility of chemical spills, leaks, dumping and nuclear melt-downs as a result of accidents or human and mechanical errors.

One of the world’s worst chemical accidents occurred in 1984 in Bhopal, when a deadly cloud of toxic gas spilled from a large pesticide plant, killing thousands of people and harming hundreds of thousands more. Following the accident, the emergency and local health services were overwhelmed; the population of Bhopal, the government of India and the industries concerned fell into a long crisis; and the health, economic and environmental consequences of the catastrophe are still felt today.

Chemical production and use has increased nearly tenfold worldwide over the last 30 years, particularly in developing countries, so a similar incident could happen again. Some countries have taken measures to prevent and prepare for major chemical accidents. However some poorer nations, or countries where industrialization is occurring very quickly, cannot ensure that their chemical plants operate safely.

In 1986, explosions at reactor No. 4 of the nuclear power plant at Chernobyl in Ukraine, led to the release of huge amounts of radioactive materials into the atmosphere. These materials were deposited over various countries in Europe, but especially over large areas of Belarus, the Russian Federation and Ukraine. The accident led to an increase in the number of cases of thyroid cancer and it had long-term consequences on mental health as a result of evacuation, relocation, and stigmatization of local populations.

In 1986, large numbers of people were poisoned as a result of a natural event, when 1.6 million tons of carbon dioxide gas were suddenly released from Lake Nyos, in Cameroon. In less than half an hour a thick cloud of gas covered a distance of 20 km, suffocating up to 1800 people and thousands of animals. Although such sudden natural events are rare and would seem unavoidable, it is possible to prevent their occurrence and to make populations less vulnerable to their effects.

In 1997–1998, Indonesia suffered prolonged and uncontrolled forest fires. They caused a dense haze containing tiny particles and toxic and irritant gases that affected over 200 million people in Indonesia and neighboring countries. In the areas reached by the smoke, there was an increased number of respiratory problems and the long-term effects on health from exposure to the haze are yet to be determined.

Although chemical and biological attacks are rare, some individuals, groups and governments are ready to release chemical or biological agents deliberately. The largest chemical weapons attack against a civilian population in modern times occurred in 1988, when Iraqi military forces used mustard gas and other chemicals against Kurds in northern Iraq.

In 1979, in Sverdlovsk, 1400 km east of Moscow, anthrax spores were accidentally released from a Soviet military microbiology facility. As a result, more than 350 people were infected and 45 to 100 of them died in a matter of days after inhaling the spores. This accident shows that microorganisms could be used as weapons of biological warfare or bioterrorism

The majority of deaths and illness related to chemical incidents are caused by the many medium-sized and small- scale events that take place every year around the world. Nevertheless, from larger scale incidents the world has learned better how to prevent and respond to chemical and radioactive threats through industrial advances and diplomatic relations. To mitigate the adverse effects of such events it is essential to have a global response network for effective surveillance and early warning.

This text is a summary of: WHO, World Health Report 2007 – A safer future: global public health security in the 21st century (2007),
Chapter 2: Threats to Public Health Security, p.26-32 


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