Objective To investigate the infestation of common vectors (namely, rodents, flies, mosquitoes, and cockroaches) in rural households in Shanxi province, China, so as to provide a basis for the assessment of environmental health hazards in rural areas. Methods In every August from 2015 to 2017, an investigation was conducted on the infestation of rodents, flies, mosquitoes, and cockroaches from 720 rural households in 20 villages in 5 towns in each of the 36 counties in Shanxi province, and statistical analyses were carried out on the resulted data. Univariate analysis of variance was used to analyze the time and space difference in the infestation of the vectors. Results There were no significant between-year differences in the infestation rates of rodents, flies, mosquitoes, and cockroaches from the rural households in Shanxi province from 2015 to 2017. During the three years, the average rodent infestation rate in the rural households across the province was 31.75%, with the highest infestation rate observed in Datong (61.00%), followed by Shuozhou (56.56%), and the lowest infestation rate was observed in Changzhi (14.89%); the rodent infestation rates in Datong and Shuozhou significantly differed from those in Lyuliang and the other seven cities (F=4.185, P=0.002). The average fly infestation rate in the rural households across the province was 78.31%, with the highest infestation rate observed in Datong (95.44%), followed by Shuozhou (91.78%), and the lowest infestation rate was observed in Changzhi (64.22%); the fly infestation rate in Datong significantly differed from that in Lyuliang and the other five cities (F=2.954, P<0.05). The average mosquito infestation rate in the rural households across the province was 12.86%, with the highest infestation rate observed in Jinzhong (23.44%), followed by Taiyuan (20.58%) and Shuozhou (20.44%), and the lowest rate was observed in Xinzhou (6.44%); there was a significant difference in mosquito infestation rate between the areas with a relatively high infestation rate (Jinzhong, Taiyuan, and Shuozhou) and the areas with a relatively low infestation rate (Xinzhou, Lyuliang, Changzhi, and Jincheng) (F=2.519, P=0.034). The average cockroach infestation rate in the rural households across the province was 2.19%, with the highest infestation rate observed in Taiyuan (6.83%), followed by Datong (2.67%) and Xinzhou (2.67%), and the lowest infestation rate was observed in Yuncheng (0.08%); there was a significant difference in cockroach infestation rate between Taiyuan and the other ten cities (F=2.068, P<0.05). Conclusion The infestation of rodents and flies in rural households in Shanxi province is relatively serious, the mosquito infestation is also unnegligible, while the cockroach infestation may be not so significant. It is necessary to refine the residential environment for inhabitants in the rural areas, enhance their awareness of disease prevention, improve their hygienic habits, and strengthen the vector control, prevention, and management, so as to keep vector-mediated diseases from spreading.

Objective To compare the black box method with the labor hour method in terms of their differences in the surveillance of mosquito density and explore the possibility of substituting black box method for the labor hour method for the surveillance. Methods The differences between the black box method and the labor hour method in terms of their performance in the surveillance of mosquito density and species were compared based on the data from three independent surveillance sites, with the correlation of the two Methods in the surveillance of the species composition ratio, sex ratio and seasonal fluctuation trends examined. Results The Results showed that the density of mosquito by black box method was 1.51 mosquitoes per site, lower than that by labor hour method (3.13 mosquito per box), with a significant difference between them (t＝4.985, P＝0.0025). In terms of the seasonal fluctuation tendency of mosquitoes, similar findings from the two Methods were obtained with good correlation and significant statistical difference (r＝0.8833, P＝0.0084). It was found that the density of female mosquitoes by the labor hour method was 1.88 mosquitoes per site, higher than that by black box method (0.50 mosquito per box) with a significant difference between them (t＝5.043, P＝0.0023). There was no correlation between the fluctuation curves of the two methods(r＝0.4812, P＝0.2743). The species and composition of mosquitoes were also different with the two different methods. The main species collected by the black box method was Culex pipiens pallens(90.6%), followed by Cx.tritaeniorhynchus(4.1%), Aedes albopictus (2.4%) and Armigeres subalbatus(2.9%), with no Anopheles sinensis found. As far as the labor hour method was concerned, Cx. pipiens pallens(42.8%) and Ar. subalbatus (40.3%) were the main species collected, with Cx. tritaeriorhynchus, Ae. albopictus and An. sinensis accounting for 11.7%, 4.7% and 0.5% respectively. In addition, there was a different sex ratio of the mosquitoes collected with the two different methods, with the number of male mosquitoes larger than that of female ones in the surveillance with the black box method, and the opposite being true for the labor hour method. The quantity of female mosquitoes collected by the black box method was close to that by labor hour method, but there was a statistically significant difference (χ²＝146.18, P＜0.001). The quantity of male mosquitoes collected by the black box method was larger than that by the labor hour method with a statistically significant difference (χ²＝513.01, P＜0.0001). Conclusion The black box method, capable of capturing more female than male mosqitoes, is applicable to the surveillance of a variety of mosquito species , but the regularity and standard operating procedure (SOP) of the method as a surveillance tool remains to be studied.

Objective To know the density of flies and their seasonal fluctuation in Minhang district for providing a scientific basis for their control. Methods The cage trap method was used, with one canopy with fresh baits set at each monitoring point for six hours (9：00 to 15：00). The flies caught by cage were collected after killed by ether and classified, and the density calculated. Results The average density of flies was 1.09 flies/cage, and that in green belt, farmers market and residential area was 1.44, 1.15 and 0.95 flies/cage, respectively. The dominant species were Musca domestica, Sericata, Sarcophagidae and Chrysomya megacephal. A bimodal density distribution with seasonal variation was seen with the peak mainly in June and September. Conclusion The density and population of flies vary with the season and breeding environment, with temperature, the breeding environment and the control measures being the major influencing factors. Integrated control measures should be taken with a top priority given to the environment management, plus chemical control to reduce the density of flies and control the prevalence of infectious diseases.