Epidemilogical Characteristics Of Hemorrhagic Fever With Renal Syndrome In Huangdao Distric Of Qingdao City

OBJECTIVEThe objective of the study is to determined the epidemilogical features of hemorrhagic fever of renal syndrome(HFRS) in humans and the animal hosts of Hantaviruses in Huangdao district, Qingdao City.Method1. Clinical characteristics and epidemiological features of the HFRS patients.106 acute sera of clinically diagnosed HFRS patients were collected by the Center for Diseases Control of Huangdao District in Qingdao from 2012 to 2013.90 convalescent phase sera were collected. The clinical data and information of the patietns were recorded. Total RNA was exracted from the acute sera of the suspected patients and ampalifed with primers specific to Hantaan and Seoul viruses with nested RT-PCR, The PCR amplified fragments were sequenced and the phylogenetic tree was constucted. ELISA was used to detect Hantavirus IgM antibody and IgG antibody in acute sera and convalescent sera of the HFRS patients, respectively.2. Detection of the Hantavirus IgG in healthy person sera. Healthy person sera were collected from Huangdao District and were analyzed for Hantavirus IgG with ELISA to determine the antibody prevalence in healthy population.3. Detection of Hantavirus RNA and antibodies in the rodents and the insectivores. Rodents and insectivores were captured from December of 2012 to December of 2013 using snap-trap in the night. The animal species was identified morphologically. The lung tissues of the animals were collected aseptically and the heart blood was absorbed with a strip of sterilized filter paper from each animal. Total RNA was extracted from the lung tissues and Hantavirus RNA was amplified with RT-PCR and sequenced. Hantavirus IgG was detected from animal sera with ELISA.Result1. One hundred and six acute sera were collected from suspected HFRS patients and 18.9%(20/106) of them were positive to Hantavirus IgM. Ninety of convalescent sera were collected from suspected HFRS patients and 16.7%(15/90) were Hantavirus IgG positive. Seventy seven patients had both acute and convalescent sera,18 (23.4%) of the acute sera were Hantavirus IgM positive,15(19.5%) of the convalescent sera were Hantavirus IgG positive, and 8 patients (10.4%) were positive to Hantavirus both in acute and convalescent sera. Among 106 acute sera tested with RT-PCR,2 (1.89%) were positive to Hantaan virus.2. Sera were collected from 448 healthy persons who were 16 to 92 years old with median age of 60 years old. The ratio of male to female was 1:1.09 and different age groups had no significant difference in gender distribution. ELISA results showed that 4.46%(20/448) healthy person sera were positive to Hantavirus IgG.3. From 2012 to 2013,1,276 rodents and insectivores were captured; ELISA showed that 19.8%(253/1,276) were positive to Hantavirus IgG.4.750 animals were randomly selected for RT-PCR amplification of Hantavirus RNA,30 specimens were positive. DNA sequencing showed that 2.1%(15/750) were Seoul virus and 2.1%(15/750) were Hantaan virus. Seoul virus was amplified from 1.7% shrews, which was not considered as animal host of Seoul virus.Conclusion1.There is a high seropvelence of hantanvirus in helathy population in Huangdao District in Qingdao City, suggesting that many people were asymptmatically infected with hantaviruses in the area.2. A very small percentage of clinically diagnosed patients were positive to hantavirus IgM, suggesting that either most patients were not infected with hantaviruses or the hantavirus antibodies were destroyed during storage of the sera.3. Both Seoul virus and Hantaan virus RNA was amplified from rodents and Seoul viral RNA was amplified from shrews, suggesting that both Seoul virus and Hantaan virus exist in the area and both rodent and shrew are the animal host of hantaviruses.