TAIPEI (Taiwan News) — Kaohsiung confirmed two new local dengue cases in Sanmin District on Monday, bringing the city’s total to 12.

Health officials said the patients, two brothers in their 40s, had no recent activity in Gushan District, per CNA. Their samples will be sent to the Centers for Disease Control for genetic testing to determine whether the cases are linked to earlier infections.

The younger brother developed a fever, headache, and muscle pain on Thursday. Despite an initial negative rapid test, he later tested PCR-positive for dengue virus type 2, per Liberty Times. Contact tracing then identified his elder brother, who had shown fever and rash a day earlier, as also infected. Both are now hospitalized in isolation.

Epidemic control teams carried out inspections and chemical spraying around their residence and nearby risk zones. Nine adult mosquitoes were caught on site, raising concerns about possible community spread.

Officials urged residents in affected areas of Sanmin to seek testing if symptoms develop and to provide travel and activity histories to doctors.