The Influenza Type A virus, with the subtypes of H5 and N1, H5N1, is an avian influenza virus deadly to birds which are the original carriers of the Influenza Type A viruses.

Although the H5N1 virus does not usually infect humans, there were already 160 reported cases of humans infected by this strain of influenza virus ever since January 2004 according to the World Health Organization (WHO). Majority of the humans infected by the H5N1 virus had direct contact with living or dead infected poultry. In fact, there was only one confirmed case in which human to human transmission of the H5N1 virus occurred. Hence, the strain is still not capable of transmission beyond one person.

Out of the influenza viruses capable of infecting both birds and humans which includes the H7 subtype, the H5N1 emerged as the deadliest. The H5N1 virus was identified in the most number of cases of humans infected by avian influenza viruses and the mortality rate of humans is as high as 50 percent. This can be observed in outbreaks in Asian and European countries. It is also noted that humans below the age of 5 and above the age of 65 have the highest mortality rate due to their weak immunity systems.

Although there has only been one proven case of the human to human transmission of the avian influenza virus, there is a high possibility speculated by scientist all over the world that a new strain of the influenza virus will emerge due to the slow and gradual processes of antigenic drift and antigenic shift. If the human body has absolutely no protection against a specific strain of the influenza virus, human to human transmission of the influenza virus will be easily accomplished and the first influenza pandemic may occur in this century.

The exact date of when the influenza virus will mutate to form a new strain deadly to human beings is unknown. However, all is not lost. The present structures of the influenza viruses are monitored by global surveillance and scientists and experts from advance and high tech science laboratories all over the world are working closely with each other and racing against time to develop a vaccine against a possible new strain of the influenza virus.