Surveillance for hemorrhagic fever with renal syndrome in Zhejiang, 2016–2020

  Objective   To understand the epidemiological characteristics of hemorrhagic fever with renal syndrome (HFRS), the distribution, density and virus carriage of host animals in Zhejiang province, and provide scientific basis for the formulation of prevention and control measures.

  Methods  The incidence data of HFRS in Zhejiang from 2016 to 2020 were collected for a descriptive epidemiological analysis to understand its time, place and population distributions. The host animals were investigated at 5 surveillance areas in Zhejiang, the capture rate was investigated by the night method, and rat-shaped animal lungs and blood were collected for the hantavirus antigen and antibody detections, and analysis on the distribution and virus carriage of rodents in Zhejiang were conducted.

  Results  The annual reported case numbers and incidence rate of HFRS in Zhejiang were 349 and 0.62/100 000 in 2016, 353 and 0.63/100 000 in 2017, 327 and 0.59/100 000 in 2018, 369 and 0.63/100 000 in 2019, and 260 and 0.46/100 000 in 2020. From 2016 to 2020, a total of 14 068 rat traps were deployed in residential areas, and 622 rodents were captured, the capture rate was 4.42%, and a total of 31 875 rat traps were deployed in the field, and 2 112 rodents were captured, the capture rate was 6.63% in the 5 surveillance areas. The differences in rodent density in the filed among the 5 surveillance areas were significant (F=2.941, P=0.046). A total of 3 065 rodents were captured in the 5 surveillance areas. The predominant rodent species in the field was Apodemus agrarianus, (1 830, 59.71%); the predominant rodent species in residential areas was Rattus norvegicus (330, 10.77%), the difference was significant (χ²=1675.401, P＜0.001). A total of 3065 rodent serum samples were tested, and the antibody positive rate was 8.7% (236/2808), and a total of 3065 rodent lung specimens were tested, the antibody positive rate was 3.66% (103/2815), and the differences in rodent species which were antibody positive among the 5 surveillance areas were significant (χ²=235.762, P＜0.001); and the differences in rodent species which were antigen positive among the 5 surveillance areas were significant (χ²=116.195, P＜0.001).

  Conclusion  The density and virus carrying rate of rodents were high in the areas with high incidence of HFRS in Zhejiang. It is necessary to take targeted prevention and control measures in key areas for the better prevention and control of HFRS.