Key Points

• The gradual spread of the Aedes albopictus mosquito across France led to the expansion of the enhanced surveillance system to all departments in mainland France in 2020.

• In 2019, 29 cases of dengue and 2 cases of chikungunya were reported in the Pays de la Loire region, including 22 cases of dengue and 1 case of chikungunya during the enhanced surveillance period (May 1 to November 30).

• Despite travel restrictions due to the COVID-19 pandemic, 101 cases of dengue were reported in 2020 in the Pays de la Loire region, including 71 cases during the enhanced surveillance period, a sharp increase compared to the previous year.

• No confirmed or probable cases of Zika virus infection were reported in 2019 and 2020 in the region.

• All confirmed or probable cases identified in the region during the 2019 and 2020 seasons were imported. In 2020, nearly 90% of dengue cases were imported from the Caribbean, where a major outbreak occurred.

• In 2020, there was a 64% reduction in the proportion of cases reported through the mandatory reporting system compared to 2019.

• As of July 16, 2020, entomological surveillance, survey, and treatment missions were entrusted to Inovalys.