Enterovirus D

Enterovirus D

Enterovirus D is a genus of viruses within the family Picornaviridae, which are small, non-enveloped viruses with a single-stranded RNA genome. This genus is part of the larger group of enteroviruses, which are known to cause a variety of diseases in humans and animals. Enterovirus D is of particular interest due to its association with severe respiratory illnesses and neurological conditions.

Virology

Enterovirus D viruses are characterized by their small size, approximately 30 nm in diameter, and their icosahedral capsid structure. The genome is a positive-sense single-stranded RNA, approximately 7,500 nucleotides in length. The genome encodes a single polyprotein that is cleaved into structural and non-structural proteins. The structural proteins form the viral capsid, while the non-structural proteins are involved in viral replication and assembly.

Species and Serotypes

The Enterovirus D genus includes several species, with Enterovirus D68 (EV-D68) being the most well-known due to its association with outbreaks of respiratory illness. Other serotypes within this genus have been identified, but EV-D68 remains the most clinically significant.

Epidemiology

Enterovirus D68 was first identified in 1962 in California, but it remained relatively obscure until outbreaks in the 21st century highlighted its potential to cause severe respiratory illness. The virus is transmitted primarily through respiratory droplets, but it can also spread via contact with contaminated surfaces.

Outbreaks of EV-D68 have been reported worldwide, with notable increases in cases during the late summer and early fall. The virus can cause mild to severe respiratory illness, and in some cases, it has been associated with acute flaccid myelitis (AFM), a polio-like syndrome that results in muscle weakness and paralysis.

Clinical Manifestations

The clinical presentation of Enterovirus D infections can vary widely. Common symptoms include:

• Mild respiratory symptoms such as cough, runny nose, and fever.
• Severe respiratory illness, particularly in children and individuals with asthma.
• Neurological symptoms, including acute flaccid myelitis, which is characterized by sudden onset of limb weakness.

Diagnosis

Diagnosis of Enterovirus D infections is typically confirmed through laboratory testing. Methods include:

• RT-PCR (Reverse Transcription Polymerase Chain Reaction): This is the most common method for detecting enterovirus RNA in respiratory specimens.
• Viral Culture: Although less commonly used, viral culture can be performed to isolate the virus.
• Serology: Detection of specific antibodies can be used to confirm recent infection.

Treatment and Prevention

There is no specific antiviral treatment for Enterovirus D infections. Management is primarily supportive, focusing on relieving symptoms and maintaining respiratory function. In severe cases, hospitalization and supportive care, including mechanical ventilation, may be necessary.

Preventive measures include:

• Good hand hygiene and respiratory etiquette.
• Avoiding close contact with infected individuals.
• Disinfecting frequently touched surfaces.

Research and Future Directions

Ongoing research is focused on understanding the pathogenesis of Enterovirus D infections and developing vaccines or antiviral therapies. The link between EV-D68 and acute flaccid myelitis is an area of active investigation.

Also see

• Enterovirus
• Picornaviridae
• Acute flaccid myelitis
• Respiratory illness