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The noun virulence (Latin noun virulentia) derives from the adjective virulent, meaning disease severity. [5] The word virulent derives from the Latin word virulentus, meaning "a poisoned wound" or "full of poison". [5] [6] The term virulence does not only apply to viruses. From an ecological standpoint, virulence is the loss of fitness induced ...
Hand, foot and mouth disease (HFMD) A diagnosis usually can be made by the presenting signs and symptoms alone. If the diagnosis is unclear, a throat swab or stool specimen may be taken. Medications are usually not needed as hand, foot, and mouth disease is a viral disease that typically resolves on its own. Under research [15] [16] Sin Nombre ...
Widespread non-communicable diseases such as cardiovascular disease and cancer are not included. An epidemic is the rapid spread of disease to a large number of people in a given population within a short period of time; in meningococcal infections , an attack rate in excess of 15 cases per 100,000 people for two consecutive weeks is considered ...
Virulent Newcastle disease (VND), formerly exotic Newcastle disease, [1] is a contagious viral avian disease affecting many domestic and wild bird species; it is transmissible to humans. [2] Though it can infect humans, most cases are non-symptomatic; rarely it can cause a mild fever and influenza-like symptoms and/or conjunctivitis in humans.
Examples of common human diseases caused by viruses include the common cold, influenza, chickenpox, and cold sores. Many serious diseases such as rabies, Ebola virus disease, AIDS (HIV), avian influenza, and SARS are caused by viruses. The relative ability of viruses to cause disease is described in terms of virulence.
For example, Clostridium tetani releases a toxin that paralyzes muscles, and staphylococcus releases toxins that produce shock and sepsis. Not all infectious agents cause disease in all hosts. For example, less than 5% of individuals infected with polio develop disease. [23] On the other hand, some infectious agents are highly virulent.
Common human diseases caused by viruses include the common cold, influenza, chickenpox and cold sores. Serious diseases such as Ebola and AIDS are also caused by viruses. [50] Many viruses cause little or no disease and are said to be "benign". The more harmful viruses are described as virulent. [51]
A successful pathogen needs to spread to at least one other host, and lower virulence can result in higher transmission rates under some circumstances. Likewise, genetic resistance against the virus can develop in a host population over time. [2] [29] An example of the evolution of virulence in emerging virus is the case of myxomatosis in ...