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Canine distemper virus is closely related to measles virus and is the most important viral disease of dogs. The disease (which was first described in 1760, by Edward Jenner, the pioneer of smallpox vaccination, is highly contagious, but is well controlled by vaccination. In the 1990s, thousands of African lions died from the infection, which ...
Avian influenza, also known as avian flu or bird flu, is a disease caused by the influenza A virus, which primarily affects birds but can sometimes affect mammals including humans. [1] Wild aquatic birds are the primary host of the influenza A virus, which is enzootic (continually present) in many bird populations. [2] [3]
A newly mutated virus could circulate within the domestic and possibly resident bird populations until highly pathogenic avian influenza (HPAI) arises. This new virus is pathogenic to poultry and possibly to the wild birds that it arose from. [citation needed] Wild birds found to have been infected with HPAI were either sick or dead.
A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. [1] Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. [2] [3] Viruses are found in almost every ecosystem on Earth and are the most numerous type of biological entity.
Coronaviruses are enveloped viruses with a positive-sense RNA genome and with a nucleocapsid of helical symmetry. They infect the upper respiratory and gastrointestinal tract of mammals and birds. They are the cause of a wide range of diseases in cats, dog, pigs, rodents, cattle and humans. Transmission is by the faecal-oral route. [5]
Often, these mutations take place when the virus has first infected other animal hosts. Some examples of such "zoonotic" diseases include coronavirus in bats, and influenza in pigs and birds, before those viruses were transferred to humans. Viral infections can cause disease in humans, animals and plants.
The discovery of West Nile virus in the Western Hemisphere was heralded by an outbreak of disease in crows and other wild birds. Other emerging diseases have demonstrated linkages between animal health events and human risk, including monkeypox, SARS, and avian influenza. In outbreaks of bubonic plague, rats begin dying out before humans.
[8] [10] In 2020, reassortment (genetic "swapping") between these H5-2.3.4.4b viruses and other strains of avian influenza led to the emergence of a H5N1 strain with a H5-2.3.4.4b gene. [8] The virus then spread across Europe, first detected there in the autumn of 2020, before spreading to Africa and Asia. [1]