Argentine health officials said Saturday that four people in a clinic in northwestern Tucuman province had died of Legionnaires' disease, a relatively rare bacterial infection of the lungs.
Health Minister Carla Vizzotti told reporters that Legionnaires' had been identified as the underlying cause of double pneumonia in the four, who had suffered high fevers, body aches and trouble breathing.
The deaths, all since Monday, occurred in a single clinic in the city of San Miguel de Tucuman.
The latest, on Saturday morning, was that of a 48-year-old man with underlying health problems. A 70-year-old woman who had undergone surgery in the clinic was also a victim.
Seven other symptomatic cases have been identified, all from the same establishment and nearly all involving clinic personnel, provincial officials said.
Of those seven, "four remain hospitalized, three of them under respiratory assistance, and three are under home surveillance, with less complicated clinical symptoms," said provincial health minister Luis Medina Ruiz on Saturday.
The disease, which first appeared at a 1976 meeting of the American Legion veterans group in the U.S. city of Philadelphia, has been linked to contaminated water or unclean air-conditioning systems.
When the outbreak in Tucuman was first detected, doctors tested the afflicted for COVID-19, flu and hantavirus, but ruled all of them out.
Samples were then sent to the prestigious Malbran Institute in Buenos Aires. Tests there pointed to Legionnaires'.
Vizzotti said authorities are working to ensure the clinic is safe for patients and staff.
Hector Sale, president of the Tucuman provincial medical college, earlier this week described the bacterial infection as "aggressive."
But he added that it is not normally transmitted person-to-person, and that no close contact of any of the 11 infected people showed symptoms.