Enterovirus 68 overview: Difference between revisions
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Enterovirus 68 (EV-D68) belongs to the [[genus]] [[enterovirus]], [[serotype]] D. Its [[genome]] consists of a positive-sense ss[[RNA]] strand. Unlike other enteroviruses, EV-D68 is acid-labile and has an optimal growth at lower temperatures. Its genome contains one [[open reading frame]] ([[ORF]]) which encodes for a single [[polyprotein]], that once translated and processed yields different [[viral protein]]s. Viral serotyping is based on a [[gene]] (''VP1''), which encodes 1 of the 4 viral [[capsid]] proteins. The viral genome has undergone several rearrangements and deletions in recent years particularly of the untranslated regions (UTR), which have led to the classification of the virus into clades. EV-D68 shows [[tropism]] for the [[mucosal]] cells of the [[lower respiratory tract]], as well as for different [[leukocyte]]s. The [[virus]] recognizes [[Decay-accelerating factor]] receptor (DAF) and receptors containing sialic-acid on cell surfaces. | |||
==Differentiating Enterovirus 68 from other Diseases== | ==Differentiating Enterovirus 68 from other Diseases== | ||
Revision as of 19:50, 11 September 2014
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Alejandro Lemor, M.D. [2]; João André Alves Silva, M.D. [3]
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Synonyms and keywords: Enterovirus D-68, EV68, EV-68, EV-D68
Overview
Enterovirus 68 (EV68) is a member of the Enterovirus genus of the Picornaviridae family. It is a non-enveloped, positive-sense, single-stranded RNA virus. It is detected more frequently among pediatric patients in the United States and other countries. While enteroviruses can cause a wide range of symptoms ranging from mild febrile illness to fatal meningitis and encephalitis, EV68 is mostly associated with acute respiratory symptoms.
Historical Perspective
Human enterovirus 68 (EV-D68) was initially detected in 1962 from samples of 4 hospitalized children presenting for pneumonia and bronchiolitis in California. It is a rare disease that has recently become more evident. The most recent outbreak occurred in USA on September 2014; it involved 10 states including Colorado, North Carolina, Georgia, Ohio, Iowa, Illinois, Missouri, Kansas, Oklahoma, and Kentucky.
Pathophysiology
Unlike other enteroviruses, enterovirus 68 (EV-D68) causes respiratory disease almost exclusively. Its cellular tropism, optimal growth at lower temperatures, and acid-lability are responsible for infection of leukocytes and cells of the respiratory mucosa. The virus is able to replicate inside leukocytes, which allows it to infect the parenchymal tissue, to increase its viral load that will contribute to viral dissemination, and to activate endothelial cells that attract more leukocytes to the infection site. Although viral transmission is not fully understood, the virus can be found in respiratory secretions and may be spread from person to person via aerosol or contact transmission.
Causes
Enterovirus 68 (EV-D68) belongs to the genus enterovirus, serotype D. Its genome consists of a positive-sense ssRNA strand. Unlike other enteroviruses, EV-D68 is acid-labile and has an optimal growth at lower temperatures. Its genome contains one open reading frame (ORF) which encodes for a single polyprotein, that once translated and processed yields different viral proteins. Viral serotyping is based on a gene (VP1), which encodes 1 of the 4 viral capsid proteins. The viral genome has undergone several rearrangements and deletions in recent years particularly of the untranslated regions (UTR), which have led to the classification of the virus into clades. EV-D68 shows tropism for the mucosal cells of the lower respiratory tract, as well as for different leukocytes. The virus recognizes Decay-accelerating factor receptor (DAF) and receptors containing sialic-acid on cell surfaces.
Differentiating Enterovirus 68 from other Diseases
Enterovirus 68 infection must be differentiated from other diseases that cause fever, cough, malaise, and rhinorrhea such as: respiratory syncytial virus, adenovirus, parainfluenza virus, seasonal influenza virus B, coronavirus, and rhinovirus.
Epidemiology and Demographics
Risk Factors
Children and elderly patients have an increased risk of developing symptoms when infected with enterovirus 68.
Natural History, Complications and Prognosis
Enterovirus produces mild upper respiratory symptoms and is most common in children. Enterovirus 68 is associated with a low mortality, but complications such as severe pneumonia and superimposed infections may occur in almost one-fifth of infected patients.
History and Symptoms
Enterovirus 68 infection presents with symptoms of an acute respiratory tract infection. The most common symptoms of this viral infection include fever, cough, dyspnea, rhinorrhea, and sneezing.
Physical Examination
Patients with enterovirus 68 infection develop signs and symptoms of respiratory illness. Findings in the physical exam include fever, tachypnea, skin rash, sore throat, and wheezing.
Laboratory Findings
Laboratory findings in an enterovirus 68 infection include a positive [[PCR] assay of a nasopharyngeal swab specimen or viral culture. Serology tests have a low specificity for the diagnosis of enterovirus 68.
Chest X Ray
Imaging studies is not commonly done in patients with enterovirus 68 infection. One-fourth of patient may develop lower respiratory complications and abnormal chest X-ray findings may include infiltration and consolidation.
Medical Therapy
There is no specific antiviral treatment for enterovirus 68 infection. Current management of these patients is based on supportive care towards symptom relief and prevention of complications.
Primary Prevention
There is no vaccine against enterovirus 68. Preventive measures such as hand washing, avoiding contact with sick people and disinfecting touched surfaces are recommended.
Future or Investigational Therapies
Even though the treatment for enterovirus infection is currently with supportive care, the development of other medical therapies has increased in the past years. Immune globulin has shown clinical and laboratory improvement among some patients with enterovirus infection. Antiviral medications against enterovirus, such as pleconaril, are currently under research, but have shown benefit in patients with severe infections caused by other subtypes of enteroviruses.