Objective To investigate the biological characteristics and host distribution of Yersinia enterocolitica in Dengfeng, 2013. Methods Yersinia enterocolitica were isolated by tradition culture method. These bacteria were analyzed by the systematic biochemistry, serotype, and PCR detection methods. Results There were 1 138 samples collected in 2013. The isolation rate of Y. enterocolitica was 14.85%(169/1 138), the isolation rate of swine was 36.55%(144/394). In total, 146(86.39%), were classified into biology type 3 and O:3. The toxicity gene distribution characters were as follow:81.06%(137/169) of them were ail⁺, ystA⁺, yadA⁺, virF⁺, 5.33%(9/169) were ail⁺, ystA⁺, 12.43%(21/169) were ystB⁺, 1.18%(2/169) were ail^-, ystA^-, ystB^-, yadA^-, virF^-. Conclusion Swine were important host as pathogenic Y. enterocolitica. O:3 was the major serotype.

Objective To understand the strain of serotype, biotype, virulence genes, which cause infantile diarrhea. Methods Bacterial culture, serum agglutination method and PCR were used for serotyping, detection of virulence genes. Results A strain of Yersinia enterocolitica was isolated from the children of feces sample and the short bacillus of gram stain negative was identified under the microscope. Oxidase of the bacteria was negative, katalase was positive, no hydrogen sulfide production, urease test positive, ONPG test positive. The Y. enterocolitica strain is positive in O:3 serotyping test and it belongs to 3 biological types, carrying the virulence genes of ail⁺, ystA⁺, yadA⁺, virF⁺ but no ystB^- . Conclusion The case of infantile diarrhea disease is caused by pathogenic Y. enterocolitica.

Objective To investigate the detection rate, serotype, and virulence gene distribution of Yersinia enterocolitica isolated from live pigs in Dengfeng, China, and to provide reference for the development of preventive measures. Methods Yersinia enterocolitica was isolated from the pharyngeal swabs (tonsils) and intestinal contents (at the ileocecal junction), which were collected from the live pigs in abattoirs in Dengfeng. Biochemical identification, serotyping, and PCR detection of virulence gene were performed on the isolates. Results A total of 107 strains of Y. enterocolitica were isolated from 196 pharyngeal swabs, with a detection rate of 54.59%; 36 strains were isolated from 196 intestinal contents, with a detection rate of 18.37%. The serotype of the isolates was O∶3. Three biological types were identified as follows: typeⅠ (ail＋, ystA＋, ystB－, yadA＋, virF＋), with a ratio of 93.71% (134/143), and typeⅡ (ail＋, ystA＋, ystB－, yadA－, virF－), with a ratio of 6.29% (9/143). Conclusion The pathogenic strains are dominant among Y. enterocolitica isolated from live pigs in Dengfeng. Monitoring of Y. enterocolitica should be strengthened in the future.

【Abstract】 Objective To investigate the community structure of fleas on small mammals in eight counties of southern mountainous areas in Yunnan. Methods Small mammal hosts were captured from eight counties selected randomly in southern mountainous areas and fleas were collected from the body surface of each host. Richness (S), Shannon?Wiener’s diversity index (H′), evenness (J′) and dominance index (C′) were used to measure the community structure of fleas on the hosts. Results There were 3184 small mammals captured, which belonged to 21 species,13 genera, 5 families and 4 orders. A total of 1767 fleas were collected from the small mammal hosts and were classified into 15 species, 13 genera and 5 families. There were seven dominant small mammals like Rattus tanezumi, Mus caroli, M.pahari, R.norvegicus, Suncus murinus, R.rattus sladeni and Niniventer fulvescens, and the dominant fleas were Xenopsylla cheopis, Nosopsyllus (Nosopsyllus) wualis and Leptopsylla segnis. Conclusion There are few fleas in the southern mountainous areas of Yunnan which biodiversity is lower than that in others.

Objective To investigate the community structure of fleas on Eothenomys miletus, together with the distribution of species-abundance and the relation of species-plots. Methods 19 counties (towns) in Yunnan province of China were selected as investigation spots. Flea specimens were collected from the body surface of every rodent. Every flea was finally identified into species under a microscope. All the fleas on Eothenomys miletus were defined as one community unit. Richness( S), Shannon-Wiener's diversity index( H′), evenness( J′) and dominance index( C′) were adopted to measure the community structure of fleas. Results 2248 fleas were collected from the body surface of 1295 rodents ( Eothenomys miletus). All the fleas were identified as 10 species belong to 7 genera of 3 families. Of 10 flea species, 2 main flea species accounts for 96.66% of the total specimens. The distribution of species-abundance shows that there are 3 species with only one individual and the individuals of 2, 4, 5, 16, 45, 121 and 2052 correspond to only one species in the flea community. The species-plot relationship shows that flea species increase with the increase of mouse plots(samples). Conclusion Eothenomys miletus can host several species of fleas, but most flea species are rare ones and they have not established a stable parasitic relationship with their host. Few flea species are dominant ones with abundant individuals.