BUENOS AIRES — Every crisis is an opportunity, they say. In several neighborhoods in the Argentine capital, moves to curb the spread of the mosquito-borne Zika virus or dengue fever in several South American countries, have provided a perfect ruse for thieves to enter properties posing as municipal fumigators, Clarín reports.

Authorities have warned residents to be alert in at least six Buenos Aires districts where thieves have put on the full fumigating garb and come knocking on doors. The first to sound the alarm was a family who refused to open and immediately wrote their concerns on networking sites. "They're ringing bells saying they've come to fumigate over dengue, and they'll rip you off," one would-be victim warned.

The Neighbors' Network in the East Florida district issues an alert on Facebook. Local authorities then put out notices saying they did not just "come around" door-to-door, and people should call the police if suspicious. House calls would only happen if authorities suspected a home to be a source of Aedes Aegypti mosquitos, they stated.

The city and most of Argentina have had a particularly hot and muggy summer, while Spain's EFE agency has reported 2016 as seeing the worst dengue epidemic since 2009, with 4,000 or so registered cases. One of the worst-hit provinces, San Luis east of Buenos Aires, has put out an application allowing locals to alert authorities to the presence of stagnant pools and other mosquito hideouts.