The spread of the ‘swine flu’ also known as the H1N1 flu strain, was officially declared a pandemic on Thursday by the World Health Organization whose director said perhaps her greatest concern is how the virus will behave in the developing world.

In a video capture from video provided by the World Health 

Organization, the group`s Director-General Margaret Chan 
delivers prepared remarks on June 9, 2009. She said that 
the organization has officially declared that `swine flu,`
also known as the H1N1 flu strain has reached pandemic 
levels. (IBTimes / WHO video)

“Perhaps of greatest concern, we do not know how this virus will behave under conditions typically found in the developing world,” said Dr. Margaret Chan, director of WHO in a released statement. “To date, the vast majority of cases have been detected and investigated in comparatively well-off countries.

Concern for the virus in developing nations is high because 99 percent of maternal deaths, which are a marker of poor quality care during pregnancy, and 85 percent of the burden of chronic diseases is concentrated in low and middle income countries, she said.

The flu which was first detected in late April with many initial cases in Mexico, has now reached 74 countries and has 30,000 confirmed cases, she said.

“Further spread is considered inevitable,” she added. “The world is now at the start of the 2009 influenza pandemic.”

She raised the organization’s influenza pandemic alert from phase 5 to phase 6 after conferring with experts, saying the criteria for an influenza pandemic had been met.

“On present evidence, the overwhelming majority of patients experience mild symptoms and make a rapid and full recovery, often in the absence of any form of medical treatment,” she said.

With few exceptions, countries with large numbers of cases are those with good surveillance and testing procedures in place, she added.

The majority of cases have occurred in people under the age of 25 years, however most cases of severe and fatal infections have been in adults between the ages of 30 and 50 years, she noted

“This pattern is significantly different from that seen during epidemics of seasonal influenza, when most deaths occur in frail elderly people,” she said.

“Many, though not all, severe cases have occurred in people with underlying chronic conditions. Based on limited, preliminary data, conditions most frequently seen include respiratory diseases, notably asthma, cardiovascular disease, diabetes, autoimmune disorders, and obesity.”