Regardless of capability or wealth, no country is immune to the increasing risk of disease outbreaks, epidemics, industrial accidents and other health emergencies, according to a new World Health Organisation (WHO) report.

Public health is threatened on a global scale, and the prospect of a safer future will depend on countries working together to identify risks and acting to contain and control them, warned the WHO World Health Report 2007, entitled A Safer Future, released on Thursday.

"Some of the most serious threats to human existence are likely to emerge without warning. It would be extremely naive and complacent to assume that there will not be another disease like AIDS, another Ebola, another SARS [Severe Acute Respiratory Syndrome], sooner or later," it said.

With infectious diseases emerging faster than ever before, closer global cooperation is vital to tackle the growing health threat, and "no single country ... can alone prevent, detect and respond to all public-health threats."

According to WHO Director-General Dr Margaret Chan, "New diseases are emerging at the historically unprecedented rate of one per year ... given today's universal vulnerability to these threats, better security calls for global solidarity. International public health security is both a collective aspiration and a mutual responsibility."

Scary new world

With the advent of globalisation, health threats have become much more serious in an increasingly interconnected world, characterised by higher mobility of people, animals and goods, economic interdependence and electronic connectivity.

"The world has changed dramatically since 1951, when WHO issued its first set of legally binding regulations aimed at preventing the international spread of disease. At that time, the disease situation was relatively stable: people travelled internationally by ship, and news travelled by telegram," Chan commented.

The report noted that "Airlines now carry more than two billion passengers annually, vastly increasing opportunities for the rapid international spread of infectious agents and their vectors - an outbreak or epidemic in one part of the world is only a few hours away from becoming an imminent threat somewhere else."

Population growth, movement into previously uninhabited areas, rapid urbanisation, environmental degradation, and the misuse of antimicrobials - substances that kill or inhibit the growth of microbes, such as bacteria, fungi, viruses or parasites - constitute profound changes that "have disrupted the equilibrium of the microbial world - infectious diseases are now spreading geographically much faster than at any time in history".

According to WHO, at least 39 new pathogens have been identified since 1967, including HIV, Ebola and Marburg haemorrhagic fevers, and SARS. In addition, "centuries-old threats" like influenza, malaria and tuberculosis continue to thrive due to a combination of biological mutations, rising resistance to antibiotics and weak health systems. In the last five years, WHO has verified more than 1,100 epidemic events worldwide.

Global cooperation is essential

The report argues that the world has a collective responsibility to ensure public health security. "More than at any previous time in history, global public health security depends on international cooperation and the willingness of all countries to act effectively in tackling new and emerging threats," WHO said in a statement.
Poverty in some countries meant there were "serious gaps, particularly in health services", WHO warned, and the open sharing of medical know-how, technology and supplies between rich and poor countries was particularly essential.

The report described quarantine, sanitation and immunisation as three advances that had been vital to global public health security; they "came about separately, but gradually came to be seen as requiring international coordination" in order to be effective.

The microbes are out there, waiting

The ambitious aim of fostering collective international health action still has substantial challenges to overcome: the report cited the rapid global emergence of HIV/AIDS in the 1970s as an example of the disastrous consequences of inadequate surveillance.
"The presence of this new health threat was not detected by what were invariably weak health systems in many developing countries. It only belatedly became a matter of international concern with the first cases in the United States," the authors pointed out. Poor health systems in many developing countries were still not capable of monitoring their national health status.

Other influences could have lethal and costly repercussions, even with reliable systems in place. The report referred to unsubstantiated claims in Nigeria in 2003 that oral poliomyelitis (polio) vaccine was unsafe and left young children sterile. The result was a large outbreak of polio across northern Nigeria and the reinfection of previously polio-free areas in the south of the country. "This outbreak eventually paralysed thousands of children".

WHO also considered the public health consequences of conflicts, such as the outbreak of Marburg haemorrhagic fever during the 1975-2002 civil war in Angola, and the cholera epidemic in the Democratic Republic of Congo (DRC), in the aftermath of the crisis in Rwanda in 1994, when up to 800,000 people sought refuge across the border.

"During the first month after their arrival, close to 50,000 refugees died in a widespread outbreak of combined cholera and shigella dysentery" on the outskirts of Goma, in eastern DRC near the Rwandan border, due to poor housing and sanitation, and contamination of the only available source of water.

Mutating microbes

The prospect of microbial adaptation merits focused attention: "an organism that can replicate itself a million times within a day clearly has an evolutionary advantage, with chance and surprise on its side", WHO pointed out.

Other threats to world health include the use and misuse of antibiotics, infectious diseases following extreme weather-related events, the acute public health impact of sudden chemical and radioactive events, and the deliberate use of biological and chemical agents.

In 2002, SARS sparkerd a degree of public anxiety that virtually halted travel to affected areas and drained billions of dollars from economies across entire regions; the virulence of the disease is still fresh in global memory, and the prospect of a global (possibly Avian) influenza pandemic should raise an immediate alarm around the world.

Global efforts to control infectious diseases have already been "seriously jeopardised" by widespread drug resistance, a consequence of poor medical treatment and misuse of antibiotics, the report warned.

Besides the growing number of cases of extensively drug-resistant tuberculosis (XDR-TB) worldwide, and in southern Africa in particular, "drug resistance is also evident in diarrhoeal diseases, hospital-acquired infections, malaria, meningitis, respiratory-tract infections and sexually transmitted infections, and is emerging in HIV".

The WHO report focused on these issues mainly in the context of the revised International Health Regulations (2005), and called for their full implementation. The regulations are an international legal instrument designed for collective defence "to achieve maximum security against the international spread of diseases".