Sick I know, but announcements of newly identified "bugs" both excite and depress me. It's exciting to watch the developments unfold as scientists from around the world work to identify the "bug", determine where it came from, how it's transmitted and what the potential threat to humans is. It's depressing because each time a new "bug" is found, I kick myself for deciding to enter the world of the working rather than moving onto a masters in Epidemiology.
While there is still much to learn about the H7N9 Bird Flu strain, one thing for certain is that the death toll and number of infections in China from the strain of bird flu first found in humans last month has ticked up daily. As of April 9, the virus has infected 28 people and killed eight in China. However, none of the people who have had close contact with the victims have shown symptoms of the flu (at least not yet), but the WHO is investigating two family clusters to who are suspected of having H7N9 to determine if transmission between close family members has occurred. But for now, there is no evidence of human to human transmission.
So far, the H7N9 virus has only been found in farm-raised pigeons, chickens and quail and wild birds (which could be concerning as we are moving into migrating season). It has yet to be found in pigs or other mammals. However, one noticeable difference between the new H7N9 outbreak and the H5N1 avian influenza outbreaks of 1997 and 2003 is in how the virus is affecting birds. The H7N9 virus does not seem to be noticeably deadly among birds where as the H5N1 strain was.
According to scientists, the gene sequences confirm that this is an avian virus, and that it is a low pathogenic form (causes only mild disease in birds), but most importantly, the sequences also reveal that there are some mammalian adapting mutations in some of the genes meaning that the H7N9 virus has already acquired some of the genetic changes it would need to mutate into a form that could be transmitted from person to person. In which case, if it became easily transmissible between humans, it could cause a deadly pandemic.
For now, the big question is what will happen in the Southern Hemisphere which is just heading into their flu season. Although human-to-human transmission has not been seen yet, should it occur experts are not expecting to see any immunity to H7N9 if it does happen. While the panic button hasn't been hit yet, everyone is watching very closely and until more information is gathered current recommendations are for healthcare workers to manage all patients displaying influenza-like illness and with travel history to China in the past ten days with Routine Practices and contact, droplet and airborne precautions.