Coxsackie B virus
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Coxsackie B is a group of six serotypes of coxsackievirus (CVB1-CVB6), a pathogenic enterovirus, that trigger illnesses ranging from a mild febrile rash to full-fledged pericarditis and myocarditis (coxsackievirus-induced cardiomyopathy).<ref name="Fields Virology">Template:Cite book</ref><ref name="pmid18357765">Template:Cite book</ref>
The genome of Coxsackie B virus consists of approximately 7,400 base pairs.<ref>Template:Cite journal</ref>
Geographic distribution
The various members of the Coxsackie B group were discovered almost entirely in the United States, appearing originally in Connecticut, Ohio, New York, and Kentucky, although a sixth member of the group has been found in the Philippines.<ref name="Fields Virology" /> However, all six serotypes have a global distribution and are a relatively common cause of gastrointestinal upset. The name reflects the first isolation from Coxsackie, New York.Template:Citation needed
Transmission
Infections are most commonly spread by the Fecal-oral route, emphasizing the importance of good hygiene, especially hand-washing.<ref name="pmid18357765" /> Oral-oral and respiratory droplets can also be means of transmission.<ref name="pmid19622041" />
Epidemiology
Coxsackie B infections have been reported to account for nearly a quarter of all enterovirus infections.<ref name="pmid6091168">Template:Cite journal</ref> Nearly half of all reported cases of Coxsackie B infections occur before the age of five.<ref name="pmid6091168" /> For the CBV1 serotype, two-thirds of Centers for Disease Control and Prevention reported infections in the United States were for children under one year of age.<ref name="pmid19622041">Template:Cite journal</ref>
Symptoms
Symptoms of infection with viruses in the Coxsackie B grouping include fever, headache, sore throat, gastrointestinal distress, extreme fatigue as well as chest and muscle pain. It can also lead to spasms in arms and legs. This presentation is known as pleurodynia or Bornholm disease in many areas. Patients with chest pain should see a doctor immediately—in some cases, viruses in the Coxsackie B family progress to myocarditis or pericarditis, which can result in permanent heart damage or death. Coxsackie B virus infection may also induce aseptic meningitis. As a group, they are the most common cause of unexpected sudden death, and may account for up to 50% of such cases.<ref>Template:Cite journal</ref> The incubation period for the Coxsackie B viruses ranges from 2 to 6 days, and illness may last for up to 6 months in extreme cases, but may resolve as quickly as two days. Infection usually occurs between the months of May and June, but do not show symptoms until October in temperate Northern Hemisphere regions. People should ideally spend 1 month resting during the height of infection. Another cause of this virus is from a dirty wound from an accident.<ref name="Fields Virology" />
Diagnosis
Enterovirus infection is diagnosed mainly via serological tests such as ELISA<ref>Template:Cite journal</ref> and from cell culture.<ref name="Fields Virology" /> Because the same level and type of care is given regardless of type of Coxsackie B infection, it is mostly unnecessary for treatment purposes to diagnose which virus is causing the symptoms in question, though it may be epidemiologically useful.Template:Citation needed
Pathology
Coxsackie B infections usually do not cause serious disease, although for newborns in the first 1–2 weeks of life, Coxsackie B infections can easily be fatal.<ref name="pmid18357765" /> The pancreas is a frequent target, which can cause pancreatitis.<ref name="pmid18357765" />
Coxsackie B3 (CB3) infections are the most common enterovirus cause of myocarditis and sudden cardiac death.<ref name="pmid31230428">Template:Cite journal</ref> CB3 infection causes ion channel pathology in the heart, leading to ventricular arrhythmia.<ref name="pmid31230428" /> Studies in mice suggest that CB3 enters cells by means of toll-like receptor 4.<ref name="pmid20860480">Template:Cite journal</ref> Both CB3 and CB4 exploit cellular autophagy to promote replication.<ref name="pmid20860480" />
Diabetes
Template:Main The B4 Coxsackie viruses (CB4) serotype was suggested to be a possible cause of diabetes mellitus type 1 (T1D).<ref>Template:Cite web</ref> An autoimmune response to Coxsackie virus B infection upon the islets of Langerhans may be a cause of T1D.<ref name="pmid18357765" />
Other research implicates strains B1, A4, A2 and A16 in the destruction of beta cells,<ref name= Laitinen2014>Template:Cite journal</ref><ref name= Honkanen2017>Template:Cite journal</ref> with some suggestion that strains B3 and B6 may have protective effects via immunological cross-protection.
Treatment and Prevention
Template:As of, there is no well-accepted treatment for the Coxsackie B group of viruses.<ref name="Fields Virology" /> Palliative care is available, however, and patients with chest pain or stiffness of the neck should be examined for signs of cardiac or central nervous system involvement, respectively. Some measure of prevention can usually be achieved by basic sanitation on the part of food-service workers, though the viruses are highly contagious. Care should be taken in washing ones hands and in cleaning the body after swimming. In the event of Coxsackie-induced myocarditis or pericarditis, anti-inflammatories can be given to reduce damage to the heart muscle.Template:Citation needed
Persistent Coxsackie B virus (non-cytolytic infection)
Enteroviruses are usually only capable of acute infections that are rapidly cleared by the adaptive immune response.<ref name="Tracy2005" /><ref name="Flynn2018">Template:Cite journal</ref> However, mutations which enterovirus B serotypes such as coxsackievirus B and echovirus acquire in the host during the acute phase can transform these viruses into the non-cytolytic form (also known as non-cytopathic or defective enterovirus).<ref>Template:Cite journal</ref> This form is a mutated quasispecies<ref name="Tracy2005">Template:Cite journal</ref> of enterovirus which is capable of causing persistent infection in human tissues, and such infections have been found in the pancreas in type 1 diabetes,<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> in chronic myocarditis and dilated cardiomyopathy,<ref>Template:Cite book</ref><ref name="Tracy2005" /><ref>Template:Cite book</ref> in valvular heart disease,<ref>Template:Cite web</ref> in myalgic encephalomyelitis,<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> and in Sjögren's syndrome.<ref>Template:Cite journal</ref> In these persistent infections, viral RNA is present at very low levels, and some researchers believe it is just a fading remnant of the acute infection<ref name="Flynn2018" /> although others scientists believe this persistent viral RNA may have pathological effects and cause disease.<ref name="Zhang2004">Template:Cite journal</ref>
References
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