Enterovirus
From Wikipedia, the free encyclopedia
| Enterovirus | ||||||
|---|---|---|---|---|---|---|
| Virus classification | ||||||
|
||||||
| Species | ||||||
|
Human:
Nonhuman:
|
The enteroviruses are a genus of (+)ssRNA viruses associated with several human and mammalian diseases. Historically the most significant has been the Poliovirus (which is now nearly extinct). Other types are coxsackie and echovirus.
Enterovirus are the most common cause of aseptic meningitis and can cause serious disease especially in infants and the immunocompromised.
"Human enteroviruses (family Picornaviridae) infect millions of people worldwide each year, resulting in a wide range of clinical outcomes ranging from unapparent infection to mild respiratory illness (common cold), hand, foot and mouth disease, acute hemorrhagic conjunctivitis, aseptic meningitis, myocarditis, severe neonatal sepsis-like disease, and acute flaccid paralysis. In the United States, enteroviruses are responsible for 30,000 to 50,000 meningitis hospitalizations per year as a result of 30 million to 50 million infections. Serologic studies have distinguished 66 human enterovirus serotypes on the basis of an antibody neutralization test, and additional antigenic variants have been defined within several of the serotypes on the basis of reduced or nonreciprocal cross-neutralization between prototype and variant strains. On the basis of their pathogenesis in humans and experimental animals, the enteroviruses were originally classified into four groups, polioviruses, coxsackie A viruses (CA), coxsackie B viruses (CB), and echoviruses, but it was quickly realized that there were significant overlaps in the biological properties of viruses in the different groups. The more recently isolated enteroviruses have been named with a system of consecutive numbers: EV68, EV69, EV70, and EV71."[1]
Contents |
[edit] Transmission
Poliovirus, as well as coxsackie and echovirus are faecal-oral spread (compare with entero- - relating to the intestines).
[edit] Species and genetics
Enteroviruses are members of the picornavirus family, a large and diverse group of small RNA viruses and "is characterized by a single positive-strand genomic RNA known to have a high mutation rate caused by low-fidelity replication and frequent recombination."[2]
"The enterovirus genus comprises the following species: poliovirus, human enterovirus A (HEV-A) (coxackie A viruses and enterovirus 71), HEV-B (coxsackie B viruses, echoviruses, coxsackie A9 virus, and enteroviruses 69 and 73), HEV-C (coxsackie A viruses), HEV-D (enteroviruses 68 and 70), and at least three animal enterovirus species (bovine, simian, and porcine enteroviruses). They all contain a genome of approximately 7,500 bases and positive [(+)]-strand polarity. After infection of the host cell, the genome is translated in a cap-independent manner into a single polyprotein, which is subsequently processed by virus-encoded proteases into the structural capsid proteins and the nonstructural proteins, which are mainly involved in the replication of the virus"[3]
[edit] Poliovirus
Incubation period of poliovirus is 1-2 weeks. The prodromal phase shows: Fever, malaise, myalgia (sore muscles), sore throat, vomiting, and constipation. Poliovirus can affect the spinal cord and cause paralysis. In this case, the disease is referred to as poliomyelitis.
[edit] Coxsackie and echovirus
Coxsackie viruses (a non-phylogenic group) are mainly associated with human hand, foot and mouth disease.
Echoviruses, on the other hand, are a cause of many of the non-specific viral infections. It is mainly found in the intestine, and can cause nervous disorders.
The usual symptoms of coxackie and echovirus are: Fever, mild rash, mild upper respiratory tract (URT) illness.
[edit] Chronic fatigue syndrome
In September 2007, a study published in the Journal of Clinical Pathology reported that acute respiratory or gastrointestinal infections associated with enterovirus may be a factor in chronic fatigue syndrome. The California-based study showed a statistically significant portion of the chronic fatigue study group tested positive for a viral protein compared to the control group.[4]
[edit] Enterovirus 71 (EV71)
EV71 was first isolated and characterized from cases of neurological disease in California in 1969.[5][6] "Enterovirus 71 (EV71), the newest member of Enterovirudae, is notable for its etiological role in epidemics of severe neurological diseases in children. It appears to be emerging as an important virulent neurotropic enterovirus in the upcoming era of poliomyelitis eradication".[7] The illness usually peaks in June or July.
"Enterovirus 71 (EV71) infection may be asymptomatic or may cause diarrhea, rashes, and hand, foot and mouth disease (HFMD). However, EV71 also has the potential to cause severe neurological disease. To date, little is known about the molecular mechanisms of host response to EV71 infection. [...] EV71 infection led to increases in the level of mRNAs encoding chemokines, proteins involved in protein degradation, complement proteins, and proapoptotis proteins."[8]
"Enterovirus 71 (EV71), one of the major causative agents for hand, foot and mouth disease (HFMD), is sometimes associated with severe central nervous system diseases. In 1997, in Malaysia and Japan, and in 1998 in Taiwan, there were HFMD epidemics involving sudden deaths among young children, and EV71 was isolated from the HFMD patients, including the fatal cases. The nucleotide sequences of each EV71 isolate were determined and compared by phylogenetical analysis. EV71 strains from previously reported epidemics belonged to genotype A-1, while those from recent epidemics could be divided into two genotypes, A-2 and B."[9]
[edit] Treatment
There is no vaccine or antiviral agent known to be effective in treating or preventing EV71 infection. Experimental vaccines and antiviral agents are being worked on.[10] For example, "both bovine and human lactoferrins were found to be potent inhibitors of EV71 infection"[7] and "ribavirin could be a potential anti-EV71 drug."[11]
[edit] Malaysia and Singapore
In Malaysia, EV71 outbreaks occurred in 1997 and 2000, mainly associated with genotypes B3 and B4. Since 1997, EV71 epidemics (genotypes B and C) have been reported annually in Singapore, with genotype B4 forming the predominant causative agent of a large outbreak in 2000.[2]
[edit] Korea
In Korea, an EV71 epidemic in 2000 was caused by a relatively new genotype, C3, which has only rarely been identified outside of Korea in recent years.[2]
[edit] Taiwan
A large outbreak of HFMD due to EV71 infection occurred in Taiwan in 1998, including 129,106 case reports, 405 children with severe complications, and more than 80 deaths. After 1998, smaller EV71 epidemics occurred almost annually in Taiwan, primarily associated with EV71 viruses of genotypes C2 and B4.[2]
"Two outbreaks of hand-foot-and-mouth disease (HFMD) occurred in Taiwan between 1998 and 2000. Enteroviruses were isolated from a total of 1,892 patients in this laboratory during this period. Of the virus isolates, enterovirus 71 (EV71) was diagnosed in 44.4% of the patients (132 of 297) in 1998, 2% (13 of 646) in 1999, and 20.5% (195 of 949) in 2000. Genetic analyses of the 5�-untranslated and VP1 regions of EV71 isolates by reverse transcription-PCR and sequencing were performed to understand the diversity of EV71 in these outbreaks of HFMD. Most EV71 isolates from the 1998 epidemic belonged to genotype C, while only one-tenth of the isolates were genotype B. Interestingly, all EV71 isolates tested from 1999 to 2000 belonged to genotype B. This study indicated that two genogroups of EV71 capable of inducing severe clinical illness have been circulating in Taiwan. Furthermore, the predominant EV71 genotypes responsible for each of the two major HFMD outbreaks within the 3-year period in Taiwan were different."[5]
[edit] Hong Kong
In Hong Kong, sporadic EV71 infections with incidences of monoplegia were reported in 1987, and a fatal case was documented in 2001.[2]
The number of EV71 cases in Hong Kong in 2004, 2005, 2006 and 2007 were 35, 8, 16 and 12 respectively.[12] In 2008 , the Centre for Health Protection confirmed the total number of infections to 18 so far. In three of the cases, the children infected had traveled to Guangdong and Fujian.[13]
[edit] China
From 1999 to 2004, there were no epidemics of hand, foot, and mouth disease in Shenzhen, People's Republic of China, but each year there were small, local outbreaks associated with only a few cases of neurological disease and no reported fatalities. Genetic analysis revealed 19 cases of EV71 among 147 children who had hand, foot, and mouth disease in Shenzhen during this time.[2]
Until 2008, no large EV71 epidemic had been reported on the Chinese mainland, but sporadic infections were common in the southeast coastal area as well as inland regions, such as Beijing, Chongqing, and Jinan. From 1998 to 2004, the only EV71 viruses identified on mainland China belonged to the genotype C4, indicating far less variety in China than in Taiwan.[2]
On May 3, 2008, Chinese health authorities reported a major outbreak of EV71 enterovirus in Fuyang city (Anhui province, Chinese: 阜阳) and other localities in Anhui, Zhejiang, and Guangdong provinces. As of May 3, 2008, 3736 cases occurring mainly in children have been reported, with 22 dead and 42 critically ill. Some 415 new cases have been reported in the last 24 hours in Fuyang City alone.[14][15] As of May 5, 2008, 6,300 were sickened by the viral outbreak which killed another child, in Zhejiang raising the death toll to 26 children, with 1,198 other children affected in that province alone. Specifically, an additional 5,151 cases were reported in Anhui province with scores more in 4 other provinces. 8,531 cases of children infected with hand-foot-mouth disease (HFMD) were reported in China. All the children infected are aged below 6, with most of them being under 2.[16][17][18] As of May 7 contagious HFMD led to 28 deaths.[19] Xinhua reported the number of people infected, also rose by 4000 to 15,799.[20] The death toll rose by two to 30, on Thursday, while the number of reported cases jumped to 19,962.[21][22] It was up by 4 to 34 on Friday, and 43 as of May 16, while reported infections jumped to 24,932.[23][24]
[edit] See also
Other serious illnesses that can arise from these viruses:
- Aseptic meningitis
- Bornholm disease
- Myocarditis/pericarditis
- Neonatal myocarditis
- Herpangina, a painful mouth infection
[edit] Sources and notes
- ^ Molecular Evolution of the Human Enteroviruses: Correlation of Serotype with VP1 Sequence and Application to Picornavirus Classification J Virol. 1999 March; 73(3): 1941–1948
- ^ a b c d e f g Genetic Characteristics of Human Enterovirus 71 and Coxsackievirus A16 Circulating from 1999 to 2004 in Shenzhen, People‘s Republic of China
- ^ Biological Significance of a Human Enterovirus B-Specific RNA Element in the 3′ Nontranslated Region J Virol. 2002 October; 76(19): 9900–9909. doi: 10.1128/JVI.76.19.9900-9909.2002.
- ^ medpagetoday
- ^ a b Change of Major Genotype of Enterovirus 71 in Outbreaks of Hand-Foot-and-Mouth Disease in Taiwan between 1998 and 2000
- ^ Laboratory Investigation of a Suspected Enterovirus 71 Outbreak
- ^ a b Lactoferrin Inhibits Enterovirus 71 Infection of Human Embryonal Rhabdomyosarcoma Cells In Vitro
- ^ Identification of genes involved in the host response to enterovirus 71 infection J Neurovirol. 2004 Oct;10(5):293-304
- ^ Enterovirus 71 from fatal and nonfatal cases of hand, foot and mouth disease epidemics in Malaysia, Japan and Taiwan in 1997-1998 Jpn J Infect Dis. 1999 Feb;52(1):12-5.
- ^ DNA vaccine constructs against enterovirus 71 elicit immune response in mice
- ^ Ribavirin Reduces Mortality in Enterovirus 71–Infected Mice by Decreasing Viral Replication
- ^ sc.chp.gov.hk, Joint departmental efforts to prevent EV71
- ^ standard.com.hk, Beijing records first virus death
- ^ China on alert as virus spreads BBC News
- ^ China orders heightened efforts to stop deadly virus AP News
- ^ news.bbc.co.uk, China virus toll continues rise
- ^ www.inthenews.co.uk, Hand-foot-mouth epidemic continues to infect children across China
- ^ ap.google.com, China says 6,300 cases in viral outbreak
- ^ news.xinhuanet.com, Xinhua's tally: Death toll of hand-foot-mouth disease rises to 28 in China
- ^ www.theaustralian.news.com.au, 28 Chinese children die from virus
- ^ ap.google.com/, Death toll from child viral disease up to 30 in China
- ^ uk.reuters.com, China reports two more deaths from child virus
- ^ ap.google.com, Report: Child viral death toll up to 34 in China
- ^ ap.google.com/article, China child virus death toll up to 43
