H5N6 Avian Influenza in Human

Abstract

Human infected with animal-derived influenza has been monitored and reported every year all over the world. This disease occurs commonly in winter and spring, and most of the patients have a history of exposure to live poultry. Influenza viruses can be categorized into four types including A, B, C, and D. Type A is more common in animal infections, such as poultry and livestock. Avian influenza and avian influenza in humans can occur repeatedly and become epidemic. Influenza virus belongs to myxoviridae, which is a single-stranded RNA virus. Avian influenza in human is an acute respiratory infectious disease caused by some strains of some subtypes of avian influenza virus. At present, avian influenza viruses can be divided into 18H subtypes (H1–H18) and 11N subtypes (N1–N11), which means theoretically that there can be 198 subtypes. However, subtypes of avian influenza viruses discovered until now that infect human beings are less than ten. Among all avian viruses in the world, the subtypes occurring firstly in China include H7N9, H5N1, H10N8, H5N6, H9N2, and H7N4. H5 and H7 are highly pathogenic avian influenza (HPAIV) [1–3]. Wild birds are natural hosts of avian influenza virus, and the virus carried by wild birds will not induce symptoms of infection. In most cases, the low pathogenic subtype virus causes mild symptoms when transmitted from wild birds to domestic poultry. Highly pathogenic avian influenza (HPAI) derives from poultry adaptive mutants. If transmitted back to wild birds, some of the viral strains will cause serious infection and even death of them. For example, infection induced by highly pathogenic avian influenza H5N1 in 2006 caused deaths of thousands of wild birds in Qinghai Lake of Western China. There are still many subtypes of viruses that have not surfaced yet. Human beings have no immunity to avian influenza virus. The mortality of infection with avian influenza virus is high and the virus may mutate. The reasons for high alertness of avian influenza include both the its easy tendency to mutate and the impossibility for immunity generated post to infection to persist too long. It is commonly considered in the medical field that avian influenza in humans may be the greatest potential threat to human beings, and it can be said now it is just the end of the beginning of a war between human and avian influenza virus.