Analysis of severe human adenovirus infection outbreak in Guangdong Province, southern China in 2019

During 2018–2019, a severe human adenovirus(HAdV) infection outbreak occurred in southern China. Here, we screened 18 respiratory pathogens in 1704 children(≤ 14 years old) hospitalized with acute respiratory illness in Guangzhou, China, in 2019. In total, 151 patients had positive HAdV test results; 34.4%(52/151) of them exhibited severe illness. HAdV infection occurred throughout the year, with a peak in summer. The median patient age was 3.0(interquartile range: 1.1–5.0) years. Patients with severe HAdV infection exhibited increases in12 clinical indexes(P ≤ 0.019) and decreases in four indexes(P ≤ 0.007), compared with patients exhibiting nonsevere infection. No significant differences were found in age or sex distribution according to HAdV infection severity(P > 0.05); however, the distributions of comorbid disease and HAdV co-infection differed according to HAdV infection severity(P < 0.05). The main epidemic types were HAdV-3(47.0%, 71/151) and HAdV-7(46.4%,70/151). However, the severe illness rate was significantly higher in patients with HAdV-7(51.4%) than in patients with HAdV-3(19.7%) and other types of HAdV(20%)(P < 0.001). Sequencing analysis of genomes/capsid genes of 13 HAdV-7 isolates revealed high similarity to previous Chinese isolates. A representative HAdV-7isolate exhibited a similar proliferation curve to the curve described for the epidemic HAdV-3 strain Guangzhou01(accession no. DQ099432)(P > 0.05); the HAdV-7 isolate exhibited stronger virulence and infectivity, compared with HAdV-3(P < 0.001). Overall, comorbid disease, HAdV co-infection, and high virulence and infectivity of HAdV-7 were critical risk factors for severe HAdV infection; these data can facilitate treatment, control, and prevention of HAdV infection.