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Objective:To analyze the epidemiological characteristics of hemorrhagic fever with renal syndrome (HFRS) in Qiqihar City, and to understand the epidemic and development rules of HFRS, and to provide scientific basis for formulating targeted prevention and control measures.Methods:The data of HFRS cases in Qiqihar City from 2016 to 2020 were collected from the China Disease Control and Prevention Information System by retrospective analysis, and the three distributions (time, region and population distribution) of HFRS were analyzed by descriptive epidemiology. At the same time, the monitoring data of rats in Nehe City from 2016 to 2020 were collected from the Nehe Municipal Center for Disease Control and Prevention for descriptive analysis.Results:From 2016 to 2020, 868 HFRS cases were reported in Qiqihar City, with 10 deaths. The average annual incidence rate was 3.26/100 000, the average annual mortality rate was 0.04/100 000, and the case fatality rate was 1.15%. From 2016 to2020, the incidence rates were 3.23/100 000, 3.31/100 000, 3.22/100 000, 4.10/100 000 and 2.43/100 000, respectively. Incidence occurred in all months of the year, with the peak period from October to December (490 cases in total). The top five counties(cities) with the incidence of HFRS were Nehe City (7.46/100 000), Keshan County (5.03/100 000), Gannan County (3.84/100 000), Fuyu County (3.82/100 000) and Tailai County (3.63/100 000). Among the patients, 76.04% (660/868) were male and 23.96% (208/868) were female; the age of onset was mainly 30-69 years old, accounting for 81.57% (708/868) of the total cases; the occupation distribution was mainly farmers, accounting for 75.46% (655/868) of the total cases. The results of rat monitoring in Nehe City from 2016 to 2020 showed that Rattus norvegicus was the dominant species in the field and village, accounting for 65.13% (581/892) and 80.21% (466/581), respectively. In spring, the rat density in the field and village was 3.37% (397/11 771) and 6.64% (275/4 141), respectively; in autumn, the rat density in the field and village was 8.47% (495/5 843) and 9.40% (306/3 254), respectively. The virus carrying rate of Rattus norvegicus was high, 13.14% (131/997); the infection rate of Rattus norvegicus was also high, 15.15% (151/997); the virus carrying rate and infection rate in the village were higher than those in the field (χ 2 = 6.87, P = 0.009; χ 2 = 13.05, P < 0.001). Conclusions:The incidence of HFRS in Qiqihar City is relatively stable from 2016 to 2018, rising in 2019 and falling back in 2020; the onset time is mainly in autumn and winter, mainly male and farmers. From 2016 to 2020, among all counties (cities, districts) in Qiqihar City, the incidence of HFRS in Nehe City is high, and the density of rats in autumn is higher than that in spring. Rattus norvegicus is the main species of rats, with high virus carrying rate and infection rate.
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Objective@# To learn the population,virus status and viral types of hantavirus（HV）hosts in Tiantai County of Zhejiang Province from 2011 to 2018,and to provide evidence for hemorrhagic fever with renal syndrome（HFRS）control. @*Methods@# Rodents in Tiantai County were captured by night trapping method. After the species and age of rodents were identified,the composition of rodent species,dominant species and density of rodents were analyzed. The lungs and blood of rodents were sampled to detect the antigen and antibody of HV by immunofluorescence method. The HV antigen-positive lung samples were detected by RT-PCR with specific primers of HV S fragment,then HV was isolated and identified by inoculating Vero-E6 cells.@*Results@# The average rodent density in Tiantai County from 2011 to 2018 was 4.44%. The rodent density in the field and residential areas were 4.94% and 2.23%,respectively. Ten species of rodents were identified,with Apodemus agrarius dominant in the field and Rattus norvegicus in the residential areas. Sixty-seven lung samples were HV antigen positive（4.13%）,one from Rattus norvegicus and the other sixty-six from Apodemus agrarius. Seventy-nine blood samples were HV antibody positive（4.86%）,all from Apodemus agrarius. Thirty-four HV antigen-positive lung samples were positive（50.75%）after RT-PCR amplification. Twenty-two strains of virus were isolated and all of them were from Apodemus agrarius,including twenty-one strains of Hantaan type（HTN）and one strain of Seoul type（SEO）.@*Conclusion @#In Tiantai County,Apodemus agrarius is the main source of HFRS infection;the main epidemic type of HV is HTN and SEO is first found in Apodemus agrarius.
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Objective To analyze the data collected from surveillance sites in Shanxi province in epidemiological investigations during 2004 - 2008 and understand the influence of such factors as rat density and vectorial quantities on plague epidemic intensity, thus provide some scientific basis for plague control and prevention. Methods To collect the data of surveillance during 2004 - 2008 in the 12 counties of plague surveillance by retrospective method. Sort and analyze the collected data according to the requirement of operational scheme for plague surveillance-calculate the rat density of spermophilus dauricus, meriones meridianus and the small rodents, and the flea index and the flea infection ratio of body flea, burrow track, cave. The results of serological tests were analyzed at the same time. Results As showed in the results, the mean density of spermophilus dauricus was 1.12 merely in each hectare, and that of meriones meridianus and small rodents were 7.42%(2130/28 700) and 8.03%(3886/48 400), respectively. The flea infection rate of spermophilus dauricus and meriones meridianas were 25.78% ( 1933/7497 ) and 44.19% (2028/4598), respectively;the flea index of spermophilus dauricus and meriones meridianus were 0.59 and 1.84, respectively. The number of nests excavated with flea for spermophilus dauricus was 70, and the numbers of nests and flea were 362 and 333, respectively. The flea infection rate was 19.34 % (70/362), and the flea index was 0.92. The number of nests excavated with flea for meriones meridianus was 34, and the numbers of nests and flea were 177 and 124, respectively. The flea infection rate was 19.21%(34/177), and the flea index was 0.70. The number of caves explored for spermophilus dauricus was 7171,and the number of burrows with flea was 62, so the flea infection rate was 0.86%(62/7171 ), and the flea index was 0.01. Conclusions With a relatively high density and large quantity and considering the epidemic features of animal plague in periphery provinces in recent years, plague may still happen and spread in Shanxi province diespite the negative results of all those serological tests, by means of importing from other provinces.
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Objective To evaluate the risk of plague occurrence via surveying and analyzing indoor rat density and flea index in natural villages having previous plague experience. Methods During August to September 2007, 30 natural villages experiencing previous plague were selected based on the surveillance data, and then all households were coded with numbers and 20 households in each village were randomly selected via computer. Cages and sticky papers were set in 600 selected households to capture rats and fleas. Rat density, flea prevalence, flea index and median were estimated. Results One hundred thirty-three Rattus flavipectus and 33 Suncus murinus were caught and averaged rat density was 2.8 rats per one hundred cage. nights (166/6000), the median was 5 rats each village. One hundred and one mice infected fleas, flea prevalence on rats was 60.8% (101/166), 296 Xenopsylla cheopis and 48 Leptopsylla segnis were collected. Rat flea index was 2.1 fleas per rat (344/166). A total of 315 dissociated flea was caught, average dissociated flea index was 0.026 fleas per sticky paper (315/11888). The median was 5.5 dissociated fleas per village. Of dissociated fleas, Ctenocephalides felis felis (205) and Xenopsylla cheopis (103) accounted for 97.8% (308/315). The proportion for species of the rat flea and the dissociated flea was different(Fisher test: P < 0.01). The rat flea was significantly associated with the rat density(r = 0.68, P < 0.01), but the dissociated flea was significantly associated with neither the rat density(r = -yield than fried wheat batter(χ2 = 5.59, P < 0.05). Conclusions In these villages having previous plague experience of Lianghe County, Rattusflavipectus was dominant species of indoor rats, Xenopsylla cheopis and Ctenocephalides felis felis were dominant species of rat flea and dissociated flea, respectively. Mengsong, Bangdu, and Tangjiatun village had potential risk of plague emergence.