Enterovirus D68 epidemic, UK, 2018, was caused by subclades B3 and D1, predominantly in children and adults, respectively, with both subclades exhibiting extensive genetic diversity

Enterovirus D68 (EV-D68) has recently been identified in biennial epidemics coinciding with diagnoses of non-polio acute flaccid paralysis/myelitis (AFP/AFM). We investigated the prevalence, genetic relatedness and associated clinical features of EV-D68 in 193 EV-positive samples from 193 patients in late 2018, UK. EV-D68 was detected in 83 (58%) of 143 confirmed EV-positive samples. Sequencing and phylogenetic analysis revealed extensive genetic diversity, split between subclades B3 (n=50) and D1 (n=33), suggesting epidemiologically unrelated infections. B3 predominated in children and younger adults, and D1 in older adults and the elderly (P=0.0009). Clinical presentation indicated causation or exacerbation of respiratory distress in 91.4% of EV-D68-positive individuals, principally cough (75.3%), shortness of breath (56.8 %), coryza (48.1%), wheeze (46.9 %), supplemental oxygen required (46.9 %) and fever (38.9%). Two cases of AFM were observed, one with EV-D68 detectable in the cerebrospinal fluid, but otherwise neurological symptoms were rarely reported (n=4). Both AFM cases and all additional instances of intensive care unit (ICU) admission (n=5) were seen in patients infected with EV-D68 subclade B3. However, due to the infrequency of severe infection in our cohort, statistical significance could not be assessed.

Automated summary

EV-D68 was detected in 58% of the EV-positive samples from 193 patients in the UK. The virus showed extensive genetic diversity, with two subclades B3 and D1, suggesting unrelated infections. B3 was more common in children and younger adults, while D1 was predominant in older adults. Most EV-D68 positive individuals presented with respiratory distress, including cough, shortness of breath, coryza, wheeze, supplemental oxygen required, and fever. AFM cases and ICU admissions were associated with EV-D68 subclade B3. However, statistical significance could not be assessed due to the infrequency of severe infection in the cohort.