Mysterious Visitor - Prevention Knowledge for Emerging Infectious Diseases

Author: Meng Qinghua
Publisher:
Publish Date: 2005-12-01
Features: Avian influenza is the short form of avian influenza, a contagious disease complex caused by a subtype of influenza A virus. It is classified as an A-type infectious disease (a severely infectious disease requiring strict management and monitoring) by the World Organization for Animal Health, also known as fowl plague or European fowl plague. From the above introduction, you might think that avian influenza has been around for a long time and is not something that "emerged" only in the past one or two years. In fact, the avian influenza virus is a vagrant from millions of years ago; it cannot survive independently and must in the bodies of other cells to complete its life activities. This vagrant has been searching for a suitable land for survival and reproduction, from in ancient single-celled organisms to advanced organisms like humans. Among the organisms that have once provided a place for the avian influenza virus, some died out rapidly after the vagrant took residence, some completely drove the vagrant out, and more adapted and coexisted peacefully after mutual adjustment.
According to the type of pathogen, avian influenza can be divided into three major categories: highly pathogenic, low pathogenic, and non-pathogenic. Non-pathogenic avian influenza does not cause obvious symptoms and only produces viral antibodies in infected birds. Low pathogenic avian influenza can cause mild respiratory symptoms in birds, reduced appetite, decreased egg production, and occasional deaths. Highly pathogenic avian influenza is the most severe, with high morbidity and mortality rates. Infected flocks often suffer "total wipeout." Scientifically speaking, the transmission of avian influenza is much more complex than that of diseases like hepatitis that we commonly see. First, because there are many types of avian influenza, it is easily mutated; second, it can infect a wide variety of organisms, including domestic poultry, waterfowl, and mammals; and last, these influenza viruses have different specific requirements for their hosts. A certain avian influenza virus may specifically infect one type of animal, and these animals are not necessarily capable of mutual transmission. Infections between species are selective, sometimes unidirectional, and at other times bidirectional.