Par
Mathias Souteyrat
Published on
; Updated on July 21, 2025 at 11:01 a.m.
After a first case of indigenous dengue reported on July 4, ARS Auvergne-Rhône-Alpes received on July 15 the report of a 2ᵉ Aboriginal case, still in Saint-Chamond (Loire), near Saint-Etienne. What we know.
“Not possible to establish the link”
On July 15, 2025, the ARS received the report on a second case of indigenous dengue. This is the second indigenous case of dengue identified this year in Saint-Chamond, in the Loire and in Auvergne-Rhône-Alpes.
At this stage, it is not possible to establish a link with the 1st indigenous case identified in Saint-Chamond. Investigations are still underway.
Confirm the presence of tiger mosquitoes in the sectors
ARS and its partners are mobilized to prevent tiger mosquitoes in the vicinity to transmit the disease to other people: several actions are carried out in a well -defined perimeter.
An entomological survey was carried out on July 18, 2025: it confirmed the presence of tiger mosquitoes in the sectors frequented by the infected person and to inform the inhabitants of an adulticide treatment.
People who were contaminated during a stay in tropical zone
Most of the time, the dengue cases reported in mainland France relate to people who have been contaminated during a stay in tropical areas. If people come back infected, these are imported cases.
The tiger mosquito present on our territory can be infected by pricking a person who has contaminated in tropical zone and, by spice it, contaminate a person who has not traveled. It is then an indigenous case.
Dengue’s symptoms occur on average within 4 to 7 days after the infective bite.
A demoustication operation
A demoustication operation will take place on the night of Monday, 21 to Tuesday, July 22 to limit the risk of transmission. Residents of the sectors concerned were informed by a flyer placed in their mailbox. A hundred houses are affected.
An epidemiological survey, door-to-door, will be carried out on July 22, by ARS and public health agents France, with the inhabitants of the place frequented by the infected person.
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