Infectious diseases are spreading faster than ever before, the World Health Organization annual report says.
Sharing data is crucial to curb viruses like bird flu, the WHO says
With about 2.1 billion airline passengers flying each year, there is a high risk of another major epidemic such as Aids, Sars or Ebola fever.
The WHO urges increased efforts to combat disease outbreaks, and sharing of virus data to help develop vaccines.
Without this, it says, there could be devastating impacts on the global economy and international security.
In the report, A Safer Future, the WHO says new diseases are emerging at the "historically unprecedented" rate of one per year.
Since the 1970s, 39 new diseases have developed, and in the last five years alone, the WHO has identified more than 1,100 epidemics including cholera, polio and bird flu.
"It would be extremely naive and complacent to assume that there will not be another disease like Aids, another Ebola, or another Sars, sooner or later," the report says.
Sharing of medical data, skills and technology between rich and poor nations is "one of the most feasible routes" to health security, it says.
The WHO is embroiled in a dispute with Indonesia over its H5N1 bird flu virus samples.
Infectious diseases emerging at a rate of one or more a year since the 1970s
These include bird flu, Sars, also Ebola, Marburg and Nipah viruses
Flu pandemic could affect more than 1.5 billion people or 25% of world population
Comeback by cholera, yellow fever and epidemic meningococcal disease in the last quarter of the 20th Century
685 verified events of international public health concern from September 2003 to September 2006
Growth of anti-microbial resistance, notably drug-resistant TB
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Jakarta has refused to share its samples with the WHO amid fears that pharmaceutical companies will use them to make vaccines that are too expensive for Indonesia.
China only started sharing its H5N1 samples in June.
The WHO report also urges governments to be open about disease outbreaks, saying nearly half of all outbreak alerts it receives come from the media.
Drug resistance also poses a threat to disease control, the WHO says, blaming misuse of antibiotics and poor medical treatment, particularly in the case of tuberculosis.
In an introduction to the report, WHO Director-General Margaret Chan says co-operation is crucial to combat outbreaks.
"Given today's universal vulnerability to these threats, better security calls for global solidarity," Dr Chan says.
"International public health security is both a collective aspiration and a mutual responsibility."