A serum epidemiological investigation of Tibetan sheep plague in Qinghai Province / 中华地方病学杂志

Objective In order to acquaint with the prevalence of Tibetan sheep plague in this area, we conducted a serum epidemiological investigation of Tibetan sheep plague in Qinghai Province. Methods Indirect hemagglutination assay (IHA) and colloidal gold immunochromatography (GICA) were applied to test serum samples of Tibetan sheep and whole blood samples from jugular vein of Tibetan sheep were collected in 8 Prefectures of Qinghai Province from 2013 to 2016. Results A total of 86 positive Tibetan sheep serum samples with plague F1 antibody were detected by both methods, and the positive rate was 0.68％ (86/12710), the samples collected in Xinghai County Hainan Prefecture had the highest positive rate, which was 5.20％ (27/519). The Haixi Prefecture and Yushu Prefecture were historical epidemic areas, the positive rates were 0.65％(15/2313) and 0.26％(6/2293), respectively. Hainan Prefecture, Guoluo Prefacture and Huangnan Prefecture were newly confirmed epidemic areas, the positive rates were 1.61％ (28/1741), 1.01％ (15/1481), and 1.44％(19/1316), respectively. The antibody titers were 1:20 to 1:5120, the samples collected in Maqin County Guoluo Prefecture had the highest titer, namely 1 :5120. Conclusions In Qinghai Province, Tibetan sheep plague is endemic, and there are outbreaks in some regions. So we have to enhance the Tibetan sheep plague monitoring especially in Marmot plague epidemic area.

Epidemiological investigation of plague F1 antibody in Tibetan sheep serum in Guoluo Prefecture, Qinghai Province / 中华地方病学杂志

Objective To understand the epidemic trend of Tibetan sheep plague in Guoluo Prefecture,Qinghai Province,we detected the plague F1 antibody in Tibetan sheep serum in this area.Methods Indirect hemagglutination test (IHA) and colloidal gold immunochromatography (GICA) were applied to test serum samples of Tibetan sheep which were separated from 5 ml whole blood drew from jugular vein in Maqin County,Maduo County,Gande County,Banma County,Jiuzhi County and Dari County in 2014 and 2015.Results We collected 1 481 serum samples,566 from Maqin County,315 from Maduo County,150 from Gande County,150 from Banma County,150 from Jiuzhi County and 150 from Dari County.Totally 14 serum samples showed F1 antibody positive,the positive rate was 0.95％ (14/1 481),and they were all from Maqin County.Conclusions This area has the prevalence of Tibetan sheep plague.Therefore,the monitoring work of Tibetan sheep plague should be strengthened.

Study of the plasmid profiles and geographical distribution of Yersinia pestis in China / 中华预防医学杂志

<p><b>OBJECTIVE</b>To analyze the plasmid features and geographical distribution characteristics of Yersinia pestis of different plague foci in China.</p><p><b>METHODS</b>A total of 2 213 Yersinia pestis strains were colected from 11 Chinese plague foci separated during 1943 to 2012, and plasmid DNA according to alkali cracking method, and measured the relative molecular mass (Mr) of plasmid DNA based on the standard plasmid contrast method, then analyzed the plasmid profiles by agar gel electrophoresis.</p><p><b>RESULTS</b>A total of 2 213 strains had 16 kinds of plasmids with different Mr, including 4×10(6), 6×10(6), 7×10(6), 13×10(6), 16×10(6), 20×10(6), 22×10(6), 23×10(6), 27×10(6), 30×10(6), 36×10(6), 45×10(6), 52×10(6), 65×10(6), 72×10(6) and 90×10(6). Plasmid were classified into 26 kinds of plasmid profiles. A total of 2 213 Yersinia pestis strains contained 4 large plasmids, 52×10(6), 65×10(6), 72×10(6) and 90×10(6), whose ratio was 22.10% (589/2 213), 75.60% (1 672/2 213), 0.17% (4/2 213), 2.12% (47/2 213), respectively. Among which, strains with plasmid 52×10(6), 65×10(6), 90×10(6) distributed in Qinghai-Tibet plateau Himalayan Marmot natural plague foci, strains with 72×10(6) plasmid only distributed in Inner Mongolia Meriones unguiculatus natural plague foci and Junggar Basin R. opimus natural plague foci, and 65×10(6) plasmid distributed in all the other foci.</p><p><b>CONCLUSION</b>Strains in Chinese 11 plague foci contained 4 kinds of large plasmid, the Mr respectively were 52×10(6), 65×10(6), 72×10(6), 90×10(6), which were classified into 26 kinds of plasmid profiles with other plasmid. These plasmid profiles distributed in relatively independent epidemic focus.</p>

The epidemiology and etiology research of Tibetan sheep plague in Qinghai plateau / 中华流行病学杂志

<p><b>OBJECTIVE</b>To identify the epidemiology and etiology characteristics of Tibetan sheep plague in Qinghai plateau.</p><p><b>METHODS</b>The background materials of Qinghai Tibetan sheep plague found during 1975 to 2009 were summarized, the regional, time and interpersonal distribution, infection routes, ecological factors for the spread were used to analyze; followed by choosing 14 Yersinia pestis strains isolated from such sheep for biochemical test, toxicity test, virulence factors identification, plasmid analysis, and DFR genotype.</p><p><b>RESULTS</b>From 1975 to 2009, 14 Yersinia pestis strains were isolated from Tibetan sheep in Qinghai province. Tibetan sheep, as the infection source, had caused 10 cases of human plague, 25 plague patients, and 13 cases of death. All of the initial cases were infected due to eating Tibetan sheep died of plague; followed by cases due to contact of plague patients, while all the initial cases were bubonic plague. Cases of bubonic plague developed into secondary pneumonic plague and septicemia plague were most popular and with high mortality. Most of the Tibetan sheep plague and human plague occurred in Gannan ecological zone in southern Gansu province, which was closely related to its unique ecological and geographical landscape. Tibetan sheep plague coincided with human plague caused by Tibetan sheep, especially noteworthy was that November (a time for marmots to start their dormancy) witnesses the number of Yersinia pestis strains isolated from Tibetan sheep and human plague cases caused by Tibetan sheep. This constituted the underlying cause that the epidemic time of Tibetan sheep plague lags obviously behind that of the Marmot plague. It was confirmed in the study that all the 14 strains were of Qinghai-Tibet Plateau ecotype, with virulence factors evaluation and toxicity test demonstrating strains as velogenic. As found in the (Different Region) DFR genotyping, the strains isolated from Yushu county and Zhiduo county were genomovar 5, the two strain isolated from Nangqian county were genomovar 5 and genomovar 7, while those isolated Delingha region were genomovar 8.</p><p><b>CONCLUSION</b>Tibetan sheep were vulnerable to plague infection, hence causing human plague as the infectious source. The Yersinia pestis strains isolated from Tibetan sheep plague carried pathogen characteristics of Qinghai-Tibet plateau plague, developing many new characteristics of such plague.</p>

Regional genotyping and the geographical distribution regarding Yersinia pestis isolates in China / 中华流行病学杂志

<p><b>OBJECTIVE</b>To type Yersinia (Y.) pestis isolates under different regions (DFR) and to observe their geographical distributions in China.</p><p><b>METHODS</b>23 DFRs primers and PMT1 (plasmid) primer were used to verify the DFR genomovars of Y. pestiss strains from 11 plague foci in China. A total of 3 044 Y. pestis isolates were involved for analysis on DFR profiles with the characteristics of geographical distribution.</p><p><b>RESULTS</b>52 genomovars were verified in 3 044 Y. pestis strains in China in which 19 genomovars as major and 33 genomovars as minor genomovar. 21 new genomovars, namely genomovar 32 to genomovar 52 were described on the basis of 31 genomovars previously confirmed. Three new genomovars belonged to new major genomovars, namely Himalayan marmot natural plague foci of the Qinghai-Tibet plateau newly added genomovar 32 and genomovar 44 as major genomovars. Mongolian gerbil natural plague foci of Inner Mongolia plateau were newly added genomovar 50 as one of the major genomovars.</p><p><b>CONCLUSION</b>Among 21 new genomovars, 3 were major genomovars, with Chinese Y. pestis DFR as the major genomovars which had obvious distribution characteristics.</p>

Sources of infection on human plague in Qinghai province / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the biological and genetic characteristics of 119 strains of Yersinia (Y.) pestis isolated from plague patients in Qinghai province, from 1958-2012.</p><p><b>METHODS</b>Both regular methods and different region(DFR)molecular typing techniques were used to study the epidemiological characteristics on 119 strains of Y. pesticin Qinghai during 1958-2012. Sources of Y. pestis from two outbreaks, in Nangqian county in 2004 and in Xinghai county in 2009,Qinghai province were also analyzed.</p><p><b>RESULTS</b>105 strains of Y. pestis were identified as Qinghai-Tibet Plateau Ecotype while the other 6 strains as Qilian Mountains Ecotype. 84.03% (100/119) of the tested strains carried 4 virulence factors F1(+), Pst I(+), VW(+) and Pgm(+)). 97.30% (72/74) of the tested strains showed high virulence. Strains that carrying 52×10(6), 65×10(6), 92×10(6) plasmids were distributed in Hainan, Haibei, Haixi,Yushu,Guoluo, Huangnan and Huangyuan counties. Genomovar 5 and 8 were the main gene types that circling around Qinghai Lake. Genomovar 10 was found in strains of Y. pesticin Nangqian county while Genomovar 8 was found in the strains isolated from human plague patient during the epidemics in Xinghai county in Qinghai.</p><p><b>CONCLUSION</b>Data from biological and genetic analyses on the epidemics of human plague in Nangqian county in 2004 and in Xinghai county in 2009 demonstrated that methods as DFR genotyping and virulence factors profiles, as well as plasmids profiles were powerful tools in confirming the human plague epidemics and sources of infection.</p>