Enterovirus D68 (EV‑D68) is a non‑enveloped, positive‑sense RNA virus belonging to species Enterovirus D in the family Picornaviridae. It primarily causes respiratory illness and has been linked to acute flaccid myelitis, a rare neurologic condition.
Virology and clinical features
EV‑D68 has a genome of approximately 7.3 kb encoding a single polyprotein. The virus is acid‑labile and replicates optimally at cooler temperatures (~33 °C), resembling rhinoviruses more than typical enteroviruses. Its capsid binds to receptors on the respiratory epithelium, allowing efficient replication in the upper airway. Infection is often asymptomatic or produces mild symptoms such as rhinorrhea, cough, sneezing and body aches. Severe cases present with wheezing, bronchospasm or pneumonia, particularly in children with asthma or underlying lung disease. EV‑D68 spreads through respiratory droplets and contact with contaminated surfaces. As with other non‑enveloped viruses, it persists in the environment and may be less susceptible to some disinfectants. No specific antiviral therapy is available, so management is supportive. Because non‑polio enteroviruses are common and many infections are subclinical, laboratory diagnosis requires reverse transcription PCR and sequencing to distinguish EV‑D68 from other rhinoviruses and enteroviruses.
Outbreaks and notable observations
EV‑D68 was first isolated in California in 1962 and long considered rare. Interest surged after large outbreaks of severe respiratory illness in the United States during the summer and autumn of 2014, when more than a thousand confirmed cases were reported. The outbreak coincided with a marked increase in acute flaccid myelitis cases and triggered intensive surveillance in multiple countries. Biennial spikes of EV‑D68 activity were recorded in 2016, 2018 and 2022 in North America and Europe, causing hospitalizations of children and adults with asthma‑like symptoms. Viruses belonging to different clades co‑circulate and show genetic evolution, including recombination events. Environmental surveillance has detected EV‑D68 in wastewater, indicating community spread. Studies continue to explore the virus’s neurotropism and its role in AFM. EV‑D68 is a respiratory enterovirus with characteristics similar to rhinoviruses. It typically produces mild cold‑like illnesses but can lead to severe respiratory disease and, rarely, acute flaccid myelitis in children. Surveillance and infection‑control practices, especially during summer and autumn, are essential because there is no vaccine or targeted antiviral therapy. Ongoing research aims to clarify the virus’s pathogenesis and develop preventive measures. Related Terms: Enterovirus A71, Echovirus 30, Human Rhinovirus A, Human Rhinovirus B, Human Rhinovirus C