Via Nature Middle East, the most informative story I've seen so far on the current Egyptian H5N1 outbreak: Will Egypt unleash another flu pandemic? Excerpt:
Hardly a week has passed in 2015 without new cases of human H5N1 influenza infection occuring in Egypt. With at least 46 cases and 13 fatalities in just two months, the number is higher than those reported in the whole of 2014.
So, what is the status of avian flu in Egypt?
The story of H5N1 influenza in Egypt dates back to early 2006, when the first human case was detected in Qalyubia governorate shortly after the first outbreak that affected domestic poultry.
Generally, Influenza viruses are a large group of pathogens that peacefully inhabit the guts of wild migratory waterfowl. These viruses are continuously evolving and occasionally acquire certain genetic changes that enable them to switch hosts and gain a foothold in domestic birds and mammals. Some are endowed with the right key combinations for decoding human cells, causing infections that can vary from isolated and mild disease to devastating pandemics.
In case of Egypt’s first outbreak, it is believed that this H5N1 virus was a passenger on-board of a wild migratory duck1 visiting Damietta, most likely from Eurasia. Once in Egypt, the newly-arrived H5N1 virus found a hospitable host that allowed it to spread and evolve into a genetically distinct group of “naturalised” viruses. The disease was declared endemic in 2008, and after this recent surge of human cases, Egypt now has the highest number of confirmed human H5N1 cases worldwide.
Another important subtype, known as H9N2, was reported to co-circulate2 with H5N1 in chickens, with evidence of human exposure3 and a recent case of a boy in Aswan.
Fortunately, so far, transmission of H5N1 viruses from chickens to humans was very inefficient and no sustained human-to-human transmission has been detected. If these H5N1 viruses becoming human-adapted, and with the current volume of air passengers, an isolated outbreak could turn into a pandemic in no time.
Pandemics don’t just cause deaths, which we know through modeling studies will be highest in developing countries, but have hefty economic tolls. A recent PNAS study4 has estimated the cost of an influenza pandemic to be somewhere between $374 billion to $7.3 trillion depending on its severity.