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Global Public Health Threats
Context - Global public health security depends on actions to prevent and respond to threats
that endanger the collective health of the global population. Those threats 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 covers a wide range of complex and daunting issues,
including the health consequences of human behavior, climate change, weather-related
events and infectious diseases, as well as natural catastrophes and man-made disasters,
all of which are discussed here.
Latest update: 10 October 2008
1. Introduction: Health Risks in a Globalized World
Over the last two centuries, science made huge progress in the fight
against infectious disease. But
the biggest battles may still be to come:
- With the increase in plane traffic, contagious illnesses
spread farther and faster than ever.
- Some diseases, such as
tuberculosis are now becoming
resistant to antibiotics.
- Old enemies like polio
refuse to go away.
- Others like smallpox
which have been eradicated threaten a devastating comeback if
- New diseases are emerging at the unprecedented rate of one per
These and other threats are explored by the World Health Organization,
which recommends ways countries can cooperate more closely to protect
global public health.
2. What steps were taken to contain disease outbreaks in the past?
Plague doctor from Rome, engraving by Paul Fürst, 1656
Throughout history, humanity has been challenged by devastating
outbreaks of infectious diseases.
Separating the sick from the healthy is an ancient approach to disease
control, notably for
practice became known as “quarantine” in the late
14th century, when people arriving in ports from
areas were isolated for at least 40 days. Quarantine became commonplace
over the following centuries, although it proved to be largely
ineffective on its own.
A breakthrough in the understanding of how disease spreads came during
epidemic in London in the
mid-19th century, when an British doctor, John Snow,
discovered that cholera was transmitted through contaminated water. His
discovery led to improvements in water sanitation in industrialized
countries that greatly reduced the risk of the disease. Cholera,
however, remains a major health risk in developing countries where clean
water is lacking.
In the 18th century, another British doctor, Edward Jenner,
vaccine for smallpox,
one of the oldest and deadliest of human diseases. In 1979, a global
immunization campaign succeeded in eradicating the disease. Small
samples of the virus have been kept
for research purposes, which raises fears that the virus could reappear
as a devastating biological weapon.
The need for international coordination on public health led to the
creation of the WHO in 1948.
International health regulations
were established in 1969 to limit the spread of
infectious diseases across
The regulations were widened and strengthened in 2005 because in
today’s highly mobile world, borders cannot stop the spread of diseases,
and because new diseases are appearing, and spreading from animals to
3. How is human behavior undermining collective health?
Some 50 000 Rwandan refugees died of cholera in a crowded camp in
Many public health threats are due to human action or lack thereof
whether deliberate or not.
In the absence of major health threats, governments tend to lower
their guard and spend less on public health. For instance, large-scale
insecticide spraying campaigns in
the 1960s nearly eradicated many diseases carried by insects, but these
re-emerged after spraying programmes stopped.
Warfare is another threat to public health – and not
just because people die in the fighting. Armed conflict can destroy
health care systems, leaving people more vulnerable to
infectious disease, especially
populations displaced by conflict. For instance, some 50 000 people
who fled the ethnic bloodshed in Rwanda in 1994
died of cholera within a month of
their arrival at a crowded refugee camp.
The widespread and sometimes
incorrect use of antibiotics
has favored the emergence of
bacteria that no longer respond to
standard treatments. This threatens our ability to treat major killers
Poor animal feeding and rearing practices can cause
disease outbreaks which may then spread from animals to humans. In fact,
many new and emerging diseases, such as
mad cow disease, originate from
Changes in climatic conditions can modify the geographic spread of
infectious diseases. For instance,
increased rainfall can put people at a greater risk to be
infected by some illnesses carried
Use of chemicals and reliance on
nuclear energy call for public health security
measures. There is always a risk of spills, leaks, accidents and
deliberate releases which could threaten health.
4. Which new health threats have emerged in recent years?
Three events illustrate new health threats of the 21st
century: the 2001 anthrax letters
in the United States, the emergence of
SARS in Asia in 2003, and the
illegal dumping of chemical waste in Ivory Coast in 2006.
In 2001, letters containing
were mailed to several U.S. media offices and two U.S. senators, killing
five people and infecting 17
others. These attacks caused huge alarm and prompted a massive public
health response. They showed the potential of
bioterrorism to cause social and
economic havoc and prompted a profound rethinking of threats to national
and international security.
Acute Respiratory Syndrome) killed hundreds of people and affected
thousands during a 2003 epidemic
raising the threat of a worldwide epidemic (or
“pandemic”). Previously unknown,
this pneumonia-like disease is
caused by a virus transmitted by
close contact with an infected
person. Believed to have originated in China, it spread swiftly around
the world, apparently passed on by people traveling by plane. It brought
travel to affected areas to a standstill and drained billions of dollars
from Asian economies.
Not only the international mobility of people, but also the global
movement of products can have serious health consequences. In August
2006, a cargo ship traveling from Europe to various African ports
illegally unloaded and dumped over 500 tons of
chemical waste in Ivory Coast. Tens of thousands of
people went to medical centers with health complaints and fears linked
to the chemical waste, overwhelming the medical system that was already
short-staffed and under-equipped. Sixty-nine people were admitted at the
hospital, and at least eight of them died as a result of the incident.
5. Why is influenza the most worrisome potential global health emergency?
Avian influenza forced the slaughter of millions of domesticated
Source: Jan Tabery
infectious disease commonly known
as flu, is caused by a virus that
mutates frequently. Occasionally a particularly virulent strain of the
virus spreads swiftly around the world, affecting or even killing a
large proportion of the population. This constitutes a
pandemic. The world has suffered
several influenza pandemics over the last century including the
1918-1919 “Spanish Flu” that killed millions.
Every year, human influenza
rapidly spreads around the world in
of significantly lesser proportion than pandemics, but still resulting
in an estimated three to five million cases of severe illness and as
many as 500 000 deaths, mostly amongst the elderly.
For the last 50 years, a global surveillance network has been
monitoring the constantly changing influenza
viruses, and guiding the
preparation of seasonal vaccines.
is an emerging disease, and the current
virus causing it, known as H5N1,
has decimated wild bird populations in parts of the world and forced the
slaughter of millions of domesticated birds. While the virus has caused
a number of infections in humans who had close
contacts with infected birds, it
has not yet mutated into a form that spreads easily from person to
person. But authorities are preparing for this possibility. By some
predictions, H5N1 could create a
pandemic affecting about 1.5
billion people and causing enormous economic and social disruption.
WHO has developed a strategic
action plan to help countries prepare for an influenza
pandemic and has assisted countries
that have experienced outbreaks of human cases of
avian influenza. In order to
further strengthen the international response, the
United Nations System Influenza Coordination (UNSIC)
was established in 2005 to respond to government requests for
coordinated and sustained international support to implement avian and
human influenza programmes.
6. Why is drug-resistant tuberculosis a growing public health concern?
Affected patients can be unresponsive to one or several drugs.
Source: Adam Ciesielski
caused by airborne bacteria, is a
leading killer among infectious
diseases. Drug-resistant strains of tuberculosis have emerged,
compromising our ability to treat it. Cases of “extensively
drug-resistant tuberculosis” have been confirmed in at least 37
countries. Affected patients are unresponsive not only to the standard
antibiotic treatment, but also to
several new stronger antibiotics,
and drug resistant tuberculosis
may be as contagious as treatable strains.
While bacteria can naturally
develop resistance to antibiotics,
“extensively drug-resistant tuberculosis”
generally develops as a result of patients not fully following the
prescribed treatment. This can be due to poor supervision, both of the
patient and the medical staff, disruptions in drug supplies and poor
Because AIDS weakens the immune
system, its spread has contributed significantly to the resurgence of
tuberculosis as a major public
health threat. The concentration of
HIV-infected people in hospitals
exacerbates the risk of catching tuberculosis. In patients infected with
HIV, untreated tuberculosis will cause death in weeks.
7. Why is polio still a threat?
Vaccinations and close monitoring has nearly succeeded in
Poliomyelitis, often called
polio, is a viral disease
attacking the nervous system, which
can lead to paralysis. By the end of the 20th century,
vaccinations and close monitoring had nearly succeeded in eradicating
it. However, in 2003, Nigeria stopped vaccinating children in parts of
the country because of unsubstantiated claims that the oral vaccine was
unsafe, giving rise to a large polio outbreak. It left thousands of
children in Nigeria paralyzed and spread to countries in Africa, Asia
and the Middle East. Under international pressure, Nigeria resumed
vaccination the following year but the
epidemic continued until
Today polio cases are once again
declining but the Nigerian experience is a reminder of the need to
remain alert and ready to respond to any outbreak or mutation of the
virus. These efforts must continue
after polio is eradicated in the wild, in case samples of the virus
preserved for research are accidentally or deliberately released.
8. Conclusion: strengthening global health security
It is necessary that all countries have a robust health system to
ensure an unbroken line of defense against
infectious diseases. Developing
countries, however, are struggling to provide basic health care to their
Besides strong health care, more cooperation between countries,
international organizations and different sectors of society would help
prevent public health emergencies from becoming international threats.
To achieve the highest possible level of global public health
security, WHO recommends:
- Full implementation of
international health regulations
by all countries.
- Stronger international disease control programmes and
- Open sharing of know-how, technologies and materials,
including viruses and
- Strengthening public health infrastructures to effectively
anticipate and respond to emerging threats.
- Bringing public policy sectors, such as health, agriculture,
trade and tourism, and legislation in line with the new health
- Increased resources for training, surveillance, prevention and