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Viral evolution is an important aspect of the epidemiology of viral diseases such as influenza (influenza virus), AIDS , and hepatitis (e.g. HCV). The rapidity of viral mutation also causes problems in the development of successful vaccines and antiviral drugs , as resistant mutations often appear within weeks or months after the beginning of a ...
An individual's immunity can be acquired via a natural infection or through artificial means, such as vaccination. [51] When a critical proportion of the population becomes immune, called the herd immunity threshold (HIT) or herd immunity level (HIL), the disease may no longer persist in the population, ceasing to be endemic. [5] [26]
Vaccines may consist of either live or killed viruses. [87] Live vaccines contain weakened forms of the virus, but these vaccines can be dangerous when given to people with weak immunity. In these people, the weakened virus can cause the original disease. [88]
Viral phylodynamics is the study of how epidemiological, immunological, and evolutionary processes act and potentially interact to shape viral phylogenies. [1] Since the term was coined in 2004, research on viral phylodynamics has focused on transmission dynamics in an effort to shed light on how these dynamics impact viral genetic variation.
Pasteur's theory was in direct opposition to contemporary theories of disease, such as the miasma theory. It was not until Robert Koch's 1891 proofs, for which he was awarded a Nobel Prize in 1905, that microorganisms were confirmed as the cause of infectious disease. [185] Viruses were confirmed as human pathogens in 1901, with the discovery ...
Gamma phage, an example of virus particles (visualised by electron microscopy) Virology is the scientific study of biological viruses.It is a subfield of microbiology that focuses on their detection, structure, classification and evolution, their methods of infection and exploitation of host cells for reproduction, their interaction with host organism physiology and immunity, the diseases they ...
“This idea of natural immunity is not really panning out with this virus,” Dr. Hilary Fairbrother, an emergency medicine physician based in Houston, TX, said on Yahoo Finance Live (video above).
New viruses and strains of viruses were discovered in every decade of the second half of the 20th century. These discoveries have continued in the 21st century as new viral diseases such as SARS [72] and nipah virus [73] have emerged. Despite scientists' achievements over the past one hundred years, viruses continue to pose new threats and ...