Abstract:

Objective Given that an outbreak of dengue was occurring in neighboring city of Ningbo, to reduce the risk of local transmission caused by imported cases, to strengthen monitoring of Aedes albopictus and to provide a basis for the control of dengue vector in Ningbo city. Methods The densities of Ae. albopictus larvae in residential quarters of cities or countryside and nurseries in 11 counties, cities or regions of Ningbo were monitored by Breteau index(BI) method from 2017-09-11 to 2017-11-10, and the relationships between mosquito densities and meteorological factors were analyzed by Spearman correlation analysis and multiple linear regression analysis. Results Almost all the BI was above 5, the Dengue virus trasmission threshold, among the monitoring sites. During most of the monitoring period, the BI was above 20. The BI of later monitoring declined, but still above dangerous threshold. The BI of urban districts(17.88) was significantly lower than that of suburb(31.44); The BI of nurseries(40.25) was higher than that of residential quarters of cities(13.10) or countryside(29.46). Mosquito densities were significantly associated with average temperature(R=0.899, P=0.015), especially average minimum temperature(R=0.943, P=0.005). Conclusion The densities of Ae. albopictus larvae were generally higher above the Dengue virus trasmission threshold, and there were potential risks of dengue epidemic in Ningbo city. The surveillance system should be strengthened, and multi-layered technology of prevention and control should be reserved. Besides, average temperature, especially average minimum temperature, had a significant influence on mosquito densities.

Key words: Dengue fever, Aedes albopictus, Breteau index, Meterological factors

摘要：

目的 为降低周边城市暴发登革热引起本地传播的风险，加强宁波市白纹伊蚊的监测，为登革热媒介防控提供依据。方法 2017年9月11日至11月10日，在宁波市11个县（市、区）采用布雷图指数（BI）法监测城镇居民区、农村居民区及托幼机构3种生境的白纹伊蚊幼虫密度，并采用Spearman相关分析法和多元线性回归分析法分析蚊虫密度与气象因素的关系。结果 宁波市每个监测点均超过BI<5的安全水平，其中大部分监测点BI>20，后期监测BI有所下降，但仍处于危险的阈值范围内。市区平均BI （17.88）低于非市区（31.44）；托幼机构平均BI （40.25）高于城镇居民区（13.10）和农村居民区（29.46）。蚊虫密度与平均气温（R=0.899，P=0.015），尤其与平均最低气温（R=0.943，P=0.005）显著相关。结论 宁波市伊蚊幼虫密度较高，存在登革热流行的潜在危险，应加强监测并储备多层次的防控技术。另外，平均气温尤其是平均最低气温对蚊虫密度有重要影响。

关键词: 登革热, 白纹伊蚊, 布雷图指数, 气象因素