Epidemic process and influencing factors of hemorrhagic fever with renal syndrome: a review / 中国血吸虫病防治杂志

Hemorrhagic fever with renal syndrome (HFRS) is a category B infectious disease caused by hantaviruses that cause acute kidney injury and has a high mortality rate, and HFRS control has been given a high priority in China. It has been found that hantavirus types are closely associated with selective host transformation and regional adaption, and continue to evolve in the form of gene recombination. The severity of HFRS varies in hantavirus types. In addition, global environmental changes and alteration of host animal behaviors accelerate Hantavirus genome variations, and large-scale land reclamation and infrastructure building increases the likelihood of human contacts with hosts and disease-transmitting vectors, thereby increasing the risk of HFRS development. This review summarizes the main characteristics and influencing factors pertaining to the epidemic process of HFRS, so as to provide insights into effective prevention and control of this infectious disease.

Predictors for abundance of Rattus tanezumi in households of commensal rodent plague foci / 中华流行病学杂志

Objective To explore the predictors on the abundance of Rattus (R.) tanezumi in households of commensal rodent plague foci.Methods Thirty natural villages that experienced previous plague cases in Lianghe county,Yunnan province,were selected followed by random selection of 20 households in each village through computer technique.Live traps were set in households to capture small mammals which were then identified to species in the field according to their morphological features.Data on potential factors for abundance of R.tanezumi were collected through questionnaires and field observation and were coded and computerized using EpiData software and further analyzed by hurdle regression model under R software.Results A total of 166 rodents (133 R.tanezumi and 33 Suucus murinus) were captured.Results from final multilevel hurdle regression model showed that the likelihood of R.tanezumi captures increased by 1.67-to 2.76-fold in households belonged to Dai ethnic families that stored foodstuff in metal pails,often raising dogs,and having adjacent houses.The number of R.tanezumi captures increased by 2.18-fold in the villages where over 80％ of the households would raise chickens.In the villages with communal latrine,the likelihood and the number of R.tanezumi capture increased 1.93-fold and 2.38-fold,respectively.While the likelihood of R.tanezumi captures would reduce by 45％-61％ in those households where there were cats and cattle being raised and maize grown in the village.The number of R.tanezumi captures would reduce by 63％ in the households where there were outside toilets.Conclusion The abundance of R.tanczumi seemed to be closely related to the ecological environment factors.Programs on plague control and prevention should relate to ecological factors that influencing the abundance of R.tanezumi.

Detection and preliminary study of a family carrying a CCR5Δ32 deletional mutation / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the frequencies of chemokine (C-C motif) receptor 5 gene (CCR5)Δ32 deletional mutation of in Han and Dai populations from Yunnan province. Immortalized cell lines were derived from a family carrying the CCR5Δ32 mutation.</p><p><b>METHODS</b>Blood samples of 346 Han and 355 Dai individuals were collected for genotyping. The coding regions of CCR5 gene were amplified with PCR followed by agarose gel electrophoresis. Suspected mutations were verified with DNA sequencing. Immortalized cell lines were constructed by using Epstain Barr virus and cyclosporine A. The difference between the cell lines and original blood samples was verified with PCR.</p><p><b>RESULTS</b>One ethnic Han individual was confirmed to be heterozygous for a deletional mutation by sequencing, which has led to discovery of a family with CCR5Δ32. Nine immortalized cell lines were established from this family, and no difference between the cell lines and original blood samples was detected by PCR.</p><p><b>CONCLUSION</b>Together with previous reports, this study has indicated a significant difference in CCR5Δ32 among different ethnic groups in China. Established immortalized cell lines can also provide material for future research.</p>

The survey of rat density and flea index in households in villages having previous plague experience in Lianghe County, Yunnan Province in 2007 / 中国地方病学杂志

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.

Nucleic acid sequence homologous analysis of the 6 kb plasmid of Yersinia pestis / 中国地方病学杂志

Objective To analyze nucleic acid sequence homology of the 6 kb(pYC) plasmid of Yersina. pestis (Y. pestis) isolated from Yurman by searching GenBank. Method The search of sequence similarity was accomplished with BLAST. Results The pYC plasmid sequence had high homology with some genes in nueleotide sequence, such as: 97.1% homology with Shigella sonnei pKYM, 92.1% homology with Haemophilus influenzae(H. influenzae) gene, Salmonella typhi (S. typhi) gene LT2 and plMVSI with 88.2% and 87.2% of homology respectively, Escherichia coli(E, coli) O157:H7 and K-12, ECOR31 with 81.4%, 81.4% and 84.7% of homology respectively. This plasmid ORFs could code for some proteins which were similar with others in GenBank, such as: ORFi and H. paragallinarum replication protein B(47.2%), ORF4 and E. coli hypothetical protein(52.7%), ORF5 and Y. pseudotuberculosis Tile (48.3%), ORF6 and E. coil Pilx5/VirB5-1ike protein (42.3%), Y. enterocolitica TriD protein(38.5%), ORFIO and S. typhimurium LT2, E. coli O157:H7 hypothetical protein(83.1% and 81.9%, respectively), ORF11 and E. coli, damage-inducible protein J(81.4%). Conclusions The pYC plasmid sequence has high homology with a few bacterial genes of Enterobacteriaceac. This plasmid may code for some proteins that are similar with hypothetical protein, damnge-indncible protein, TriD and TilE protein, Pilx5/VirB5-hke protein of Escherichia or Yersinia.