Estimation of the actual disease burden of human H7N9 infection in Jiangsu of eastern China from March 2013 to September 2017

The actual incidence of human H7N9 infection is supposed to be much higher than the documented laboratory-confirmed cases. In this study, we estimated the number of the actual H7N9 cases in Jiangsu, China using a probabilistic multiplier model. Then, disability adjusted life years (DALYs), direct and indirect economic loss caused by this disease were calculated and analyzed. Till September 2017, the estimated total number of H7N9 cases was 2 952 [median, 90% probability range (PR): 1 487−22 094], which was 11.8 times (5.9−88.4) as large as the reported number. The median morbidity was estimated to be 4 (90% PR: 2−29) per 100 000 population. The total DALYs loss was 16 548 years, and the total economic loss (direct and indirect) was estimated to be RMB 1 044 618 758 (US$ 16.7 M). The average economic loss for per case and for per year was RMB 353 868 (US$ 56 440) and RMB 232 137 502 (US$ 37.0 M), respectively. The actual burden of human H7N9 infections was much heavier than what was documented. Our study provided an approach to estimate actual burden of infectious diseases using laboratory-confirmation.