H1N1 swine flu has killed more than 700 people around the world since the outbreak began four months ago, says the World Health Organization (WHO).

世界卫生组织称，自4个月前爆发以来H1N1猪流感在全球范围内已经导致700人致死。

The virus was first recorded in Mexico

This represents a jump of at least two-thirds from the last official death toll¹ figure of 429, published by the WHO on July 6.

Margaret Chan, WHO director-general, has warned that swine flu will become the biggest flu pandemic（全国流行的） ever seen.

However, most cases continue to produce only mild symptoms.

The overwhelming majority of patients usually recover, even without medical treatment, within a week of falling ill.

The WHO has said the pandemic is developing at such a high speed that it is now pointless to try to document every case.

In past pandemics, flu viruses have needed more than six months to spread as widely as the new H1N1 virus has spread in less than six weeks.

But officials have stressed that there is an ongoing²（前进的，进行的） need for all countries to monitor unusual events, such as clusters（蔟） of severe or fatal cases, or unusual clinical patterns, closely.

Some 125,000 laboratory-confirmed cases have been reported worldwide - but the number of actual cases far exceeds that.

WHO spokeswoman Aphaluck Bhatiasevi said a group of experts, including mathematicians³（数学家）, epidemiologists（流行病学家） and a virologists（滤过性病原体学者）, were examining various measures countries could take to slow the spread of the disease.

Ms Bhatiasevi said school closures could be among the recommendations, but that it was up to each country to consider appropriate steps for their situations.

Experts predict that there will be a significant surge of new cases of swine flu in the northern hemisphere when the weather begins to cool in the autumn.