The infection status of Leptospira in rodents on the Heixiazi island of Heilongjiang province, China,in 2011 / 中华预防医学杂志

<p><b>OBJECTIVE</b>To study the infection status of Leptospira in rodents on Heixiazi island Heilongjiang province in 2011.</p><p><b>METHODS</b>A total of 356 rodents were captured by night trap on the Heixiazi island from April to October 2011. The kidney tissue samples were collected by asepsis operation and the genomic DNA were extracted from them. Leptospira strains were confirmed by polymerase chain reaction(PCR) amplification of the 482 bp 23 S rDNA gene. Fifteen PCR products selected by the month were purified and sequenced by the methods of Sanger dideoxy, the sequences then compared with other Leptospira strains in Genebank, and phylogenetic analyses were drafted by software Mega 4.0.</p><p><b>RESULTS</b>Among 356 rodents, the dominant species were Clethrionomys rutilus (39.3%, 140/356) and Apodemus agrarius (36.0%, 128/356). The infection rate of Leptospira was 11.0%, with 39 rodent samples detected positive. All the rodent species were infected except for Rattus norvegicus. The infection rate was 9.4% (12/128) in Apodemus agrarius, 12.9%(18/140) in Clethrionomys rutilus, 10.8%(7/65) in Microtus fortis Buchner. No significant difference was found between the infection rate and the species of rodents by chi square test(χ(2) = 1.92, P > 0.05). Among months, the infection rate was 5.6% (4/72) in May, 8.8% (5/57) in June, 12.8% (5/39) in July, 9.8% (5/51) in August, 33.3% (11/33) in September, 22.5% (9/40) in October,but no infection in April. There was significant difference in infection in different months (χ(2) = 32.92, P < 0.05). All the Leptospira in rodents on the Heixiazi island were in the same phylogenetic branch with a high similarity of 97.1%-99.6%, close with the Australia strain U90865 by the similarity above 96.3%.</p><p><b>CONCLUSION</b>Leptospira is probably prevalent in rodents on the Heixiazi island, and the phylogene of the strains were similar. The infection rate in rodents was significantly different in months but not in hosts.</p>

The analysis of hantavirus S gene in Apodemus agrarius in Changbai area / 病毒学报

To gain more insights into epidemiologic characteristics and genotype of hantavirus in Apodemus agrarius in Changbai Area. Complete hantavirus S segment sequences were amplified by RT-PCR and sequenced. The phylogenetic trees were constructed for analysis of genetic characters of hantavirus. A total of 58 Apodemus agrarius were trapped in the epidemic areas, and complete hantavirus S segment sequences were obtained from 4 lung samples of these rodents (6. 90%0). Phylogenetic analysis of the four S segment sequences indicated that all viruses isolated from Apodemu sagrarius were closely related to genotype 6 of Hantaan virus (95. 8%-96. 3%, nucleotide identity; 98. 6%-99. 5%, amino acid identity), all of them had a specific S387 different from other genotypes of Hantaan virus.

Investigation on hantaviruses infection in rodents from free markets in Beijing areas / 中华流行病学杂志

<p><b>OBJECTIVE</b>In order to find out the factors related to hemorrhagic fever with renal syndrome (HFRS) infection, and to evaluate the probability of ecdemic hantaviruses (HV) infection in rodents in Beijing areas.</p><p><b>METHODS</b>Rodents were collected in a large-scale railway station and a produce market with 'trap nights' method from April to May, 2004. The IgG reacting sera to HV antigen were detected using ELISA. The partial M and S segment of HV from captured rodent lung samples were amplified with RT-PCR. The PCR products were purified and sequenced. BLAST program was then used to perform on nucleotide pairwise alignment with all available sequence in GenBank. The alignment of the multiply nucleotide and the deduced amino acid sequences, together with phylogenetic analysis were completed with DNASTAR software.</p><p><b>RESULTS</b>The average population density was 3.49% (24/690). The overall seroprevalence of HV infection was 8.3% (2/24). RT-PCR positive rates were 8.3% (2/24). The nucleotide sequences of 356 bp region (1958 - 2313) of M segment obtained from 2 samples were all identified to Seoul virus (SEOV), with 7.6% heterogeneity. The dc501 strain from railway station was closely related to SD227 and Hebei4 from Shandong and Hebei provinces respectively. BjFT01 strain from the farm product market had more special nucleotide transitional mutations than other known SEOV from Beijing in GenBank. This strain, together with known HN71 from Hainan province, K24-E7 from Zhejiang province, L99 from Jiangxi province and R22 from Henan province, represented a monophylogentic linkage.</p><p><b>CONCLUSION</b>The higher HV prevalence of rodents in transportation center was the potential and important risk for HFRS epidemic in Beijing. The increasing prevalence of M. musculus should call for attention. It was possible that SEOV in Beijing was imported by infected rodents through vehicles from other provinces.</p>

Study on the association between hantavirus infection and Rattus norvegicus / 中华流行病学杂志

<p><b>OBJECTIVE</b>To further understand the association of hantavirus (HV) harbored and transmitted in wild brown rats.</p><p><b>METHODS</b>Rattus norvegicus (n = 570) were trapped in 10 sites in Beijing. RT-PCR was used to test rodent lung samples for hantavirus infection. Unconditional multivariate logistic regression analysis was performed, with PCR positive as the dependent variable and the characteristics of Rattus norvegicus population as independent variables.</p><p><b>RESULTS</b>The overall HV prevalence in Rattus norvegicus was 9.1% (52/570). Significant association between HV infection in Rattus norvegicus and some biological characteristics of host population was observed. Adult Rattus norvegicus had a higher HV prevalence than juveniles. Males in the reproduction periods and rats with wounds were more likely to be infected with HV than others.</p><p><b>CONCLUSION</b>It was further confirmed that there existed parallel transmission of HV in Rattus norvegicus hosts. Aggression might be the primary mode of HV transmission among male Rattus norvegicus.</p>