Echovirus
1298668
200409939
2008-03-23T23:50:25Z
84.56.219.244
referenced
{{Taxobox
| name = ''Echovirus''
| virus_group = iv
| familia = ''[[Picornaviridae]]''
| genus = ''[[Enterovirus]]''
| species = ''[[Human enterovirus B]]''
| subdivision_ranks = Subtype
| subdivision = ''Echovirus''
}}
An '''echovirus''' is a type of [[RNA virus]] that belongs to the [[genus]] ''[[Enterovirus]]'' of the ''[[Picornaviridae]]'' family.<ref name=Sherris>{{cite book | author = Ryan KJ; Ray CG (editors) | title = Sherris Medical Microbiology | edition = 4th ed. | pages = 537–9 |publisher = McGraw Hill | year = 2004 | id = ISBN 0838585299 }}</ref> Echoviruses are found in the gastrointestinal tract (hence it being part of the enterovirus genus) and exposure to the virus causes other opportunistic infections and diseases.
==History==
The first isolation of echoviruses occurred from the [[feces]] of [[asymptomatic]] children early in the 1950s, just after [[Cell culture|cell culturing]] had been developed. The ''echo–'' part of the name was originally an [[acronym]] for "[[enteric]] cytopathic human orphan" virus: ''Orphan virus'' means a virus that is not associated with any known disease. Even though Echoviruses have since been identified with various diseases, the original name is still used.<ref name=Baron>{{cite book | author = {{subst:CURRENTMONTHNAME}} {{subst:CURRENTYEAR}}in-Murphy M, Almond JW | title = Picornavirues. ''in:'' Baron's Medical Microbiology ''(Baron S ''et al'', eds.)| edition = 4th ed. | publisher = Univ of Texas Medical Branch | year = 1996 | url = http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=mmed.section.2862 | id = ISBN 0-9631172-1-1 }}</ref>
==Description==
Echovirus is highly [[infectious disease|infectious]], and its primary target is children. The echovirus is among the leading causes of acute [[Fever|febrile]] illness in infants and young children, and is the most common cause of [[aseptic meningitis]].<ref name=eMed_629>{{eMedicine|ped|629}}</ref>
Infection of an infant with this virus following [[childbirth|birth]] may cause severe [[systemic disease]]s, and is associated with high [[infant mortality]] rates. The echovirus can mimic [[symptom]]s caused by other common [[bacteria]]l and [[virus|viral]] [[infection]]s, so echovirus infections are often treated with therapies aimed for other infections. This can lead to the evolution of [[antibiotic-resistant]] bacteria.
==Viral structure and infection==
An echovirus measures 24-30 nanometres (nm), and is similar to other viruses, since it has a naked [[protein]] [[capsid]], which makes up 75% of the virus particle that encloses a dense central core of single-stranded [[RNA]]. This RNA has a length of approximately 7.5 [[kilobase]] (kb), contains an [[RNA replicase]], [[viral-coded protein]]s, and a single [[polyprotein]] that is responsible for the formation of [[structural protein]]s and other proteins necessary for [[cellular replication]]. The structural proteins determine [[host range]] and play a very important role in delivering the RNA [[genome]] into the [[cytoplasm]] of new host [[Cell (biology)|cells]].<ref name=eMed_629 />
Some viral replication of an echovirus occurs in the [[nasopharynx]] after infection and then spreads to regional [[lymph node]]s. However, most viral particles are swallowed and they reach the lower [[gut tract]], where the virus is presumed to bind to specific [[receptor (biochemistry)|receptors]]. The virus then spreads to the lower [[intestinal tract]], replicating but not causing any major cellular effects along the way. Next, the virus spreads to many secondary sites in the body such as the [[central nervous system]], [[liver]], [[spleen]], [[bone marrow]], [[heart]] and finally the [[lung]]s. Additional replication of the virus will occur, causing symptoms 4 to 6 days after infection. The most deadly part however is delayed when symptoms of a central nervous system disease start to appear. Enteroviruses are capable of infecting any cell in the body. These viruses are highly infectious. They can spread through the air to other hosts 1-3 weeks after infection and can spread through feces to other hosts eight weeks after infection.
==Symptoms and diagnosis==
Echovirus disease occurs disproportionately in males. Infection within the first two weeks of birth can cause devastating and potentially fatal disease. In this population, death usually results from overwhelming [[liver failure]] or [[myocarditis]], rather than infection of the central nervous system. Older children and adults have a better prognosis. Myocarditis is the most frequent complication in adults.
Echovirus infections can occur in people of all age groups. However, as we get older, there is increased production of specific [[antibodies]] to the echovirus. Several studies performed during [[epidemics]] show that infants become infected at notably higher rates than older children and adults.
==Cause of infection==
Causes of echovirus infections can be placed in several categories. Main causes of infection are from overcrowded conditions such as the poor districts of a city and poor [[hygiene]]. Echoviruses are transmitted person-to-person; the fecal-oral route is the predominant mode, although transmission sometimes occurs via respiration of oral secretions such as [[saliva]]. Indirect transmission occurs through numerous routes, including via contaminated water, food, and [[fomite]]s (inanimate objects). Contaminated swimming and wading pools can also transmit the virus. Also, there are well-documented reports of transmission via the contaminated hands of hospital personnel.
==Treatment==
No specific treatment for echovirus infection is currently available. Care is directed at relief of symptoms. The anti-viral drug [[pleconaril]] interferes with the binding of the echovirus particle to the cell membrane and the drug also hinders the uncoating of [[virions]] by attaching itself to the viral protein capsid.<ref name=eMed_629 /> The pharmaceutical company, [[ViroPharma Incorporated]], ended development of pleconaril in 2004.
==In popular culture==
Echovirus 11 was the cause of an epidemic in a maternity ward in the ''[[House (TV series)|House MD]]'' episode "[[Maternity (House episode)|Maternity]]".
==References==
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[[Category:Picornaviruses]]
[[fr:Echovirus]]
[[nl:ECHO-virus]]
[[pl:Wirusy ECHO]]