GENEVA: Infectious diseases are emerging more quickly around the globe, spreading faster and becoming increasingly difficult to treat, the World Health Organisation (WHO) said on Thursday.

In its annual World Health Report, the UN agency warned there was a good possibility that another major scourge like AIDS, SARS or Ebola fever with the potential of killing millions would appear in the coming years. "Infectious diseases are now spreading geographically much faster than at any time in history," the WHO said.

It said it was vital to keep watch for new threats like the emergence in 2003 of SARS, or Severe Acute Respiratory Syndrome, which spread from China to 30 countries and killed 800 people. "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 warned.

Since the 1970s, the WHO said, new threats have been identified at an 'unprecedented rate' of one or more every year, meaning that nearly 40 diseases exist today which were unknown just over a generation ago.

Over the last five years alone, WHO experts had verified more than 1,100 epidemics of different diseases.

With more than 2 billion people travelling by air every year, the UN agency said: "an outbreak or epidemic in one part of the world is only a few hours away from becoming an imminent threat somewhere else."

The report called for renewed efforts to monitor, prevent and control epidemic-prone ailments such as cholera, yellow fever and meningococcal diseases. International assistance may be required to help health workers in poorer countries identify and contain outbreaks of emerging viral diseases such as Ebola and Marburg hemorrhagic fever, the WHO said.

It warned that 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.

This is a particular problem in tuberculosis, where extensively drug-resistant (XDR-TB) strains of the contagious respiratory ailment have emerged worldwide. "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 report declared.