Molecular Epidemiology Of Hemorrhagic Fever With Renal Syndrome In Xiangyun County,Yunnan Province

Objective:In order to understand the clinical characteristics of patients with hemorrhagic fever with renal syndrome(HFRS)and the genotypes of hantavirus(HV)infection in Xiangyun County,Yunnan Province,and to clarify the distribution of host animals and the types of HV in this County,so as to provide scientific guidance for the prevention and control of HFRS.Methods:The clinical data and sera of HFRS patients were collected from the People’s Hospital of Xiangyun County.The epidemiological data were collected by face-to-face interview with questionnaire and analyzed by Epidata3.1 and SPSS20.0.The IgM/IgG against HV in sera of HFRS patients were detected by colloidal gold method.For the investigation of host animals,the cages or traps were put in the residential areas or in the field during the day,and the traps or cages were collected in the morning of the next day.The nucleic acid of HV in the patient’s sera and the lung tissues of the host animals were amplified by reverse transcription polymerase chain reaction(RT-PCR).The obtained DNA sequences of HV were spliced with EditSeq and SeqMan in Lasergene software package,and bioinformatics analysis was performed with ClustalX2、MegAlign and MEGA-X.Results:From July 2019 to December 2020,we had collected the 128 cases of HFRS clinical data in the Department of Infection of the People’s Hospital of Xiangyun County.23.44%(30/128)of HFRS cases were clinical diagnosis cases.And the confirmed cases holded 76.56%(98/128).In Xiangyun County,HFRS casess were mainly concentrated in spring and summer,accounting for 65.17%(58/89).Among the 10 towns in Xiangyun County,25.00%(32/128)of HFRS cases lived in Xiangcheng Town,followed by Yunnanyi Town and Xiazhuang Town,accounting for 17.2%(22/128)and 14.8%(19/128)respectively.Among the HFRS patients,male:female=1.84:1.The proportion of HFRS cases from 40 year old to 59 year old was 51.56%(66/12 8).Farmers accounted for 82.03%(105/128).The average hospitalization time was about 9 days.The main clinical manifestations were fever,acute onset and fatigue,accounting for 87.50%(112/128),77.34%(99/128)and 72.66%(93/128)respectively.Among the specific clinical manifestations of HFRS,70.31%(90/128)cases had at least one pain of headache,orbital pain and low back pain.In clinical laboratory examination,21.09%(27/128)of HFRS patients had increased leukocyte count,62.50%(80/128)had thrombocytopenia,67.97%(87/128)had positive urine protein,and 75.00%(96/128)had positive HV IgM/IgG.Epidemiological investigation showed that 95.65%(44/46)of HFRS cases had not received HFRS before,95.65%(44/46)of them had not received HFRS vaccine,95.65%(44/46)had rodent activities at home,and 82.61%(38/46)had rodent activities in their workplace.The positive rate of HV in HFRS cases was 3.91%(5/128).In February 2021,93 small mammals belonging to 5 genera and 6 species were captured in Xiangyun County.The HV infection rate in small mammals was 7.53%(7/93).The 5 strains of the partial large segment sequences detected in the sera from HFRS patients had the highest similarity with Seoul orthohantavirus(SEOV)(92.27%～98.42%).The 7 strains of HV from small mammals were similar with SEOV.The similarity between the HV partial L segmet XYRn5 from Rattus norvegicus and SEOV was 97.95%.The five sequences of XYAcl5,XYAc16,XYAc17,XYAc19 and XYAc20 from Apodemus chevrieri were similar to SEOV with similarity ranging from 96.44%to 97.95%.The partial L segment XYCa93 strain from Crocidura attenuata was the closest to Puumala orthohantavirus(PUUV)with the similarity of 77.72%.In the phylogenetic analysis,the HV nuclein obtained in this study formed two large branches.One branch was clustered in SEOV,and the other branch was clustered in Luxi orthohantavirus(LUXV).SEOV formed two small branches.Conclusion:From July 2019 to December 2020,HFRS cases are mainly concentrated in spring and summer in Xiangyun Yunnan Province.Most of them are 40-59 years old and farmers.It is impossible to diagnose early HFRS only depending on clinical manifestations and general clinical laboratory examination.The diagnosis of HFRS must be combined with immunology and etiology.HFRS cases were mainly infected SEOV and host animals had been carring the various genetypes of HV in Xiangyun country,Yunnan Province.HV obtained from Crocidura attenuata had higher homology to LUXV,which indicates that HV is transmitted across species in hosts.