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.