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[12] [23] Influenza D virus causes an influenza-like illness in pigs but its impact in its natural reservoir, cattle, is relatively unknown. It may cause respiratory disease resembling human influenza on its own, or it may be part of a bovine respiratory disease (BRD) complex with other pathogens during co-infection. BRD is a concern for the ...
Variants of Influenza A virus are identified and named according to the isolate that they are like and thus are presumed to share lineage (example Fujian flu virus like); according to their typical host (example Human flu virus); according to their subtype (example H3N2); and according to their deadliness (e.g., Low Pathogenic as discussed below).
In fact, the root cause of the continuing H5N1 pandemic threat may be the way the pathogenicity of H5N1 viruses is masked by cocirculating influenza viruses or bad agricultural vaccines." [ 13 ] Dr. Robert Webster explains: "If you use a good vaccine you can prevent the transmission within poultry and to humans.
Avian influenza HA preferentially binds to alpha-2,3 sialic acid receptors, while human influenza HA preferentially binds to alpha-2,6 sialic acid receptors. [40] Usually other differences also exist. Currently, there is no human-adapted form of H5N1 influenza, so all humans who have caught it so far have caught avian H5N1.
Three virus families, Influenza virus A, B, and C are the main infective agents that cause influenza. During periods of cooler temperature, influenza cases increase roughly tenfold or more. Despite the higher incidence of manifestations of the flu during the season, the viruses are actually transmitted throughout populations all year round.
Variant influenza viruses do not normally infect humans, but when they do cause human infection, the virus can be passed from animals to humans directly, or between humans. [41] Due to human to human transmission, family and close contacts of agricultural workers are at increased risk of influenza as well.
All influenza A virus pandemics since the 1900s were caused by Avian influenza, through Reassortment with other influenza strains, either those that affect humans (seasonal flu) or those affecting other animals (see 2009 swine flu pandemic). [35] The serotypes that have been confirmed in humans, ordered by the number of confirmed human deaths, are:
The main cause of influenza recurrence is antigenic drift, which makes it essential to reevaluate and update the influenza vaccine's ingredient list every year. [23] Annual influenza outbreaks are caused by antigenic drift and declining immunity, when the residual defenses from prior exposures to related viruses are incomplete.