Surveillance for larva density of Aedes albopictus in Yiwu, Zhejiang, 2014–2020

  Objective  To analyze the larva density of Aedes albopictus in recent years in Yiwu of Zhejing province and provide evidence for the prevention and control of dengue fever.

  Methods  The data of larva density of Ae. albopictus in Yiwu from 2014 to 2020 were collected and analyzed, and software ArcGIS 10.2 was used to visualize the larva density of Ae. albopictus in local townships, and software SAS 9.4 was used to conduct Cochran-Armitage analysis.

  Results  The annual average Breteau index (BI) and Container index (CI) showed a decrease trend in Yiwu. The average BI kept below 10 in 2018 and 2020. The annual average CI reached the lowest point in 2018 and kept below 0.31 in all townships, however, the CI in 2 townships increased again in 2020. The annual average CI and permanent container index (PCI) showed decrease trends through 2014 to 2020 (Z=−3.513, P<0.05); and annual highest PCI also showed a decrease trend (Z=−1.983, P<0.05).

  Conclusion  The larva density of Ae. albopictus in Yiwu had shown a decrease trend since 2014, however, there is a risk of re-increase. Long-term prevention and surveillance should be strengthened.