Taiwan - Large-scale lethal ovitrap control program

Issues and Objectives

Dengue fever is currently the most prevalent vector-borne infectious disease in Taiwan, with Aedes aegypti and Aedes albopictus being the main vectors. Data from the annual number of locally transmitted dengue fever cases over 33 years (1987-2019, CDC Infectious Disease Statistics Information Query System) shows that the dengue fever epidemic in Taiwan has been gradually worsening, indicating that Taiwan is becoming a more favorable habitat for dengue mosquitoes to grow and reproduce, and will face a higher risk of dengue fever in the future.

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Improvement Measures Taken

To reduce mosquito vectors in the environment, the National Research Center for Mosquito-borne Infectious Diseases has implemented a trap-killing barrel program since 2018. The advantages of developing large-scale traps are threefold: 1. Large traps have a large water capacity, resulting in excellent mosquito attraction. Unlike the previously used small egg-laying barrels, they do not require weekly management; only monthly replenishment of attractants is needed, significantly reducing manual management costs. 2. The adhesive device and mosquito control agents inside the barrel attract mosquitoes to lay eggs, simultaneously eliminating them and effectively reducing the mosquito population in the environment. 3. This device consumes no energy, and the cost of consumables for one year is less than NT$1,500, resulting in low program costs.

The criteria for evaluating the placement of large bait barrels in a community include:

• shelter from rain and sun
• Population gathering places (e.g., activity centers, parks)
• The environment is dirty, messy, and poorly managed (e.g., empty houses, vacant lots).
• Disease-carrying mosquitoes prefer to live in certain environments
• Long-term monitoring of high mosquito populations
• The environment has no strong odors (e.g., public restrooms).
• Plants that do not have environmental aversion (e.g., *Hylocereus undatus*).
• The environment lacks large bodies of water (such as ponds).

Figure 1. Large baiting barrel made of adhesive angle steel (Image source: Reference URL 2)

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Results

After deploying the newly designed large-scale adhesive angle steel traps in high-risk dengue fever neighborhoods in the South and North Districts of Tainan City, a total of 34,847 eggs and 1,573 Aedes mosquitoes were captured in the South and North Districts by August 2018, demonstrating remarkable effectiveness. In addition to Aedes aegypti and Aedes albopictus, the large traps can also trap other nuisance pests such as Culex mosquitoes, Culicoides taeniorhynchus, and moth flies.

Figure 2. Effectiveness of large-scale baiting barrels (Image source: 2018 Tainan City Government Health Bureau Dengue Fever Prevention Forum - Briefing on the Effectiveness of Large-Scale Baiting Barrels)

Glossary

Climate change risk assessment: Using effective assessment tools to understand the medium- and long-term impacts of climate change on various sectors, and to propose corresponding adaptation strategies and actions to reduce the risks brought about by climate change.

Case type:

Structural and physical options: engineering techniques or reinforcement of existing structures, integrated technology development

Social options: learning and exchanging disaster knowledge in the community, and developing and applying early warning information.

Institutional options: Establishing institutions at the economic, policy, and legal levels

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Reference Websites

1. https://nmbdcrc.nhri.org.tw/2019/01/04/%e7%a4%be%e5%8d%80%e7%99%bb%e9%9d%a9%e7%86%b1%e9%98%b2%e7%96%ab%e6%96%b0%e5%8a%9b%e8%bb%8d-%e8%aa%98%e6%ae%ba%e6%96%91%e8%9a%8a%e8%a3%a1%e6%87%89%e5%a4%96%e5%90%88/.
2. https://health.tainan.gov.tw/dengue/warehouse/%7BD6DAD9BD-D038-4352-88DC-399146910DC1%7D/5)1070814%E5%8F%B0%E5%8D%97%E7%99%BB%E9%9D%A9%E7%86%B1%E9%98%B2%E6%B2%BB%E8%AB%96%E5%A3%87-%E5%A4%A7%E5%9E%8B%E8%AA%98%E6%AE%BA%E6%A1%B6%E6%88%90%E6%95%88-%E6%8E%9B%E7%B6%B2.pdf.
3. https://nidss.cdc.gov.tw/nndss/DiseaseMap?id=061.

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