Gauging the severity of a virus, particularly the new A(H1N1) influenza, can be difficult as the nature of the disease tends to differ from area to area, a World Health Organization (WHO) expert said Wednesday, according to dpa. The WHO earlier said 33 countries were reporting together 5,728 laboratory confirmed human cases of H1N1. There have been 61 deaths. Three new countries included since Tuesday were Cuba, with one case, and Finland and Thailand, each reporting two infections of what is also known as swine flu. Sylvie Briand, from the health agency's Global Influenza Programme, told reporters that the WHO will work "to improve the severity assessment" of the virus, but that there was no quantitative index to judge its strength. "For influenza, this kind of index is not very helpful, especially at the global level, since severity will vary from case to case," she said, noting that even within the same country the characteristics of the disease could be different. "In previous pandemics we have seen this," she added, saying there were "different waves, and each wave can have its own severity." The WHO's pandemic alert system, currently at phase 5, one below the highest, only tracks the geographic spread of the disease. Besides the nature of the virus, and how virulent it was, other factors also affected how strongly the disease could hit people. These included the level of governmental intervention and how the response was coordinated and the underlying health of the population affected. So far, the new virus has shown itself to be mostly mild. According to WHO figures, Mexico had 2,059 infections, including 56 deaths. The United States reported 3,009 cases, including three deaths. There was one death in Canada from 358 instances and Costa Rica has reported eight cases, including one death. There were no deaths in other countries. North America remained the only region to have confirmed cases of sustained human-to-human transmission of the virus. In Europe, the hardest hit countries were Spain with 98 cases and Britain, which reported 68.
