[Fleas notified on Microtus fuscus foci in Sichuan province].

OBJECTIVE: To analyzed the variant information on the indices regarding fleas from natural foci of Microtus plague in Sichuan epidemic area during 2000 to 2008. METHODS: Statistical and analytical methods were used on the surveillance data regarding Microtus fuscus plague. RESULTS: There were 19 flea species identified and the share of Callopsylla sparsity was 62.79 percent while the share of Amphipsylla tuta was 30.90 percent on Microtus fuscus plague. The infection rate of fleas and the flea index were the highest in October and the lowest in December and March. Species as Callopsylla sparsity, Amphipsylla tuta and Rhadinopsylla dahurica vicina could naturally infect the Yersinia pestis. CONCLUSION: Microtus fuscus plague could become epidemic when animals and flea species were infected. We should emphasis on plague monitoring program so as to prevent the occurrence of the disease.

[Monitoring the Microtus fuscus plague epidemic in Sichuan province during 2000-2008].

OBJECTIVE: To analyze the epidemic tendency of Microtus fuscus plague during 2000 - 2008 in Sichuan province. METHODS: To investigate the plague each year according to "overall Plan of the Plague in the Whole Nation" and "Surveillance Program of Sichuan Province Plague". RESULTS: There were plague epidemic from 2000 to 2008, with the average density as 312.41/ha. 42.57% of the Microtus fuscus were infected by body Fleas. The Fleas Index was 0.88 and the Index for nest Fleas of Microtus fuscus was 55.89. Six kinds of animals were infected by not only the Microtus fuscus but also herd-dog, sand fox, Tibetan sheep, domestic cats and Cricetulus longicaulatus as well. The positive rate of live Microtus fuscus was 0.32% but 22.99% in the dead Microtus fuscus. The overall positive rate on serological test was 6.70%. There were 4 Sections, 11 species and 19 kinds Fleas identified and carrying 3 kinds of fleas, Callopsylla sparsilis, Amphipsylla tutua tutua and Rhadinopsylla dahurica vicina, with the overall infection rate as 0.054%. CONCLUSION: Plague among Microtus fuscus showed a continuous epidemic in Sichuan province during 2000-2008.

[Study on the natural foci of Marmota himalayana plague in Sichuan province].

OBJECTIVE: To explore the existence of natural foci on Marmota himalayana plague in Sichuan province and to provide basis for prevention and control of the disease. METHODS: Both epidemiological investigation and laboratory tests were used to provide the host animal and fleas of the vectors with Yersinia pestis carriers. RESULTS: 30 species of animals were found to belong to 10 orders. Ochotona curzoniae and M. himalayana were the most common ones while 7 species of the fleas belonged to 7 genera and 3 families. M. himalayana was the main reservoirs while Callopsylla dolabris and Oropsylla silantiewi served as vectors. The 13 Y. pestis were identified from 43 Marmota samples. 8 samples were identified under IHA, with the highest titer of herding-dogs serum as 1:10,240. 19 samples were F1 antigen positive using RIHA and the highest titer of M. himalayana serum was 1:409,600. The major foci was 4545 km2, distributed at Dege county in Sichuan province. CONCLUSION: We have confirmed the existence of natural foci on M. himalayana plague in Sichuan province.

[Study on the application and evaluation of methods for gene and antigen detection in plague surveillance program].

OBJECTIVE: To apply and evaluate new methods regarding specific gene and antigen detection in plague surveillance program. METHODS: 1798 samples from natural foci of plague were tested, using internal quality control multiple-polymerase chain reaction, F1 antigen marked by immuno chromatographic assay and enzyme linked immunosorbent assay. Culture of Yersinia pestis and reverse indirect hemagglutination assay were used as reference diagnostic methods. RESULTS: The overall positive rate of culture on Yersinia pestis together with gene and antigen detection was 7.34%, showing an 16.81% increase when comparing to 6.28% using Yersinia pestis culture method alone. The rate of coincidence was 97.13%. CONCLUSION: The new standard being used for specific gene and antigen detection could increase the positive rate of diagnosis on plague.