Molecular investigation of infection sources and transmission chains of brucellosis in Zhejiang, China.

In the present study, a total of 7793 samples from 5 different types of hosts were collected and tested, with a seroprevalence of 2.4% (184/7793). Although the seroprevalence of human and animal brucellosis is relatively low, numbers of human brucellosis cases reported have increased continuously from 2004 to 2018. A total of 118 Brucella strains containing 4 biotypes were obtained, including Brucella melitensis bv.1 (n = 8) and bv.3 (n = 106), Brucella abortus bv.3 (n = 3) and bv.7 (n = 1). Twenty-one shared MLVA-16 genotypes, each composed of 2 to 19 strains obtained from different hosts, suggest the occurrence of a brucellosis outbreak epidemic with multiple source points and laboratory infection events. Moreover, 30 shared MLVA-16 genotypes were observed among 59.6% (68/114) B. melitensis isolates from Zhejiang and strains from other 21 different provinces, especially northern provinces, China. The analysis highlighted the imported nature of the strains from all over the northern provinces with a dominant part from the developed areas of animal husbandry. These data revealed a potential transmission pattern of brucellosis in this region, due to introduced infected sheep leading to a brucellosis outbreak epidemic, and eventually causing multiple laboratory infection events. It is urgent to strengthen the inspection and quarantine of the introduced animals.

[Risk Assessment of Snail Output Via the Mud Balls of Transplanted Seedlings in a Nursery Stock Park in Middle Region of Zhejiang Province].

Objective: To investigate the distribution of snails in a nursery stock park in the middle region of Zhejiang Province and assess the risk of snail output via the mud balls of transplanted seedlings, to provide scientific data for making strategies for snail control. Methods: We selected three species of seedlings including Osmanthus fragrans (a large tree), Camellia sasanqua (a small tree), and Purpus privet (a type of shrub) in a nursery stock park in a snail-positive middle region of Zhejiang Province during 2014-2016 to calculate the areas of regions with snails and the density of living snails. In 30 trees of each species, the distribution of snails within the seedlings ground diameter (radius of investigation, 100 cm for Osmanthus fragrans; 30 cm for Camellia Sasanqua and Purpus Privet) and in different soil layers (surface and superficial layers, 0-3 cm; deep layer, 3-10 cm) was assessed. In addition, the presence of snails in mud balls of 50 trees of Photinia fraseri (a small tree with high density of snails) was investigated to assess the risk of snail output. Results: In the planting areas of Osmanthus fragrans（3 930 m2）, Camellia sasanqua（2 000 m2）, and Purpus privet （1 700 m2）, the areas of snail-positive regions were 200, 900 and 800 m2, respectively, with the density of living snails being 0.08, 0.56 and 0.55/0.1 m2. For Osmanthus fragrans, Camellia sasanqua and Purpus privet, 238, 654 and 645 snails were detected respectively within their seedlings ground diameter, including 159（66.8%）, 461（70.5%） and 376 （58.3%） snails in the surface layer, respectively, which were significantly higher than those in the superficial and deep layers（P＜0.01）. Snails were found in all the 50 trees of Photinia fraseri（3 726 snails, 706 adult snails and 3 020 immature snails, 75 snails/tree on average）. Conclusion: There is a high density of snails in the nursery stock park in the middle region of Zhejiang Province. The snails are distributed mainly in the surface layer, suggesting a risk of snail output through mud balls.

[Analysis of cost-effectiveness of molluscacide combined with herbicide by spraying].

OBJECTIVE: To explore an economical and efficient molluscicidal method suitable for large area of nursery stock field. METHODS: Two nursery stock fields with Oncomelania hupensis were selected as experimental sites, and an experimental group and a control group were set. In the experimental group, the molluscacide and herbicide were alternately used (a purification molluscicidal method) during the period of May to October, 2011. In the control group, grass shoveling and soil burying combined with molluscacide were used in the same period. The snail control effects of the two groups were observed and the costs of the two methods were analyzed. RESULTS: No living snails were found in both experimental and control groups three consecutive years after the snail control intervention above mentioned. The costs of snail control intervention in the experimental group and control group were 0.90 and 1.80 Yuan/m2, respectively. CONCLUSION: The effect of the purification molluscicidal method in nursery stock field is satisfying, and the cost is lower.

[Observation of molluscicidal effect of black plastic film combined with carbon amide].

OBJECTIVE: To evaluate the molluscicidal effect of black plastic film combined with carbon amide. METHODS: In Jiangdong Town, Jinhua City, the field with Oncomelania hupensis in the history was selected as experimental area and divided into 3 groups: Group One was administered with black plastic film combined with carbon amide; Group Two was administered with simple black plastic film; and Group Three was a control group. RESULTS: On the 3rd, 7th, 15th, 20th and 30th day after the experiment, the mortality rates of 0. hupensis of Group One were 86.0%, 88.0%, 100%, 100% and 100% respectively, which were significantly higher than those of the control group (all P < 0.05). The differences of mortality rates between Group One and Group Two were statistically significant on the 3rd and 7th day after the experiment (Group One was superior to Group Two). CONCLUSION: The bladk plastic film combined with carbon amide can improve the molluscicidal effect.

[Cost-effectiveness analysis of mechanical and manual soil-buried methods for Oncomelania hupensis control].

OBJECTIVE: To explore a high molluscicidal efficient method in special Oncomelania hupensis snail environments. METHODS: In 2005 and 2006, in large special environments (rubble creek beaches and seepage barren hills with snails), the mechanical soil-buried method (excavator digging to bury deep snails) and manual soil-buried method were used respectively, and the results were compared for the cost-effectiveness. RESULTS: With the mechanical soil-buried method in 2006, the investment was 0.78 yuan/m2, and the compression rate of snail areas was 100%; with the manual soil-buried method in 2005, the investment was 1.34 yuan/m2, and the compression rate of snail areas was 20.26%. The former was much better than the latter. CONCLUSION: In the large special environments with snails, the mechanical soil-buried method is superior to manual soil-buried method.