But Level 6 pandemic designation does not mean H1N1 virus is becoming more dangerous.
Johannesburg, South Africa
The term pandemic does not necessarily indicate the danger of a specific illness, but rather the fact that an illness has spread geographically, both across national borders and to entirely different regions.
WHO officials have noted that while they are raising their alert to the highest level, there are no indications that the swine flu virus is mutating or adapting, or becoming more dangerous.
"A move to level 6 is not a verdict on the severity of the virus," Scotland's Health Secretary Nicola Sturgeon told Scottish lawmakers on Thursday. "It simply means that the extent of global spread now fulfills the definition of a pandemic."
To date, the swine flu has reached 74 countries, with the WHO reporting 27,737 cases including 141 deaths. The virus appears to be mild, with most cases requiring no treatment. Influenza in an average year kills up to 500,000 a year, but the last big pandemic killed about 1 million, note health officials.
In South Africa, public health officials say the implications of a Level 6 pandemic are not likely to be great. "In most cases, the swine flu virus appears to be mild, and here in South Africa, we are already entering the seasonal influenza period, so the readiness level is already high," says Dr. Frew Benson, chief director for communicable diseases at South Africa's Department of Health.
At present, the swine flu virus has not been confirmed in Africa, but poorer countries such as Zimbabwe, Zambia, or Malawi, where public hospitals are already unable to cope with the level of cases for HIV and AIDS could find themselves swamped and unable to cope with a sudden increase in swine flu cases, public health officials say.
• Information from the wires services was used in this report.