Entrance to the Luz Médica Sanatorium, in San Miguel de Tucumán, where an infectious focus is being investigated. DIEGO ARAOZ (AFP) An outbreak of bilateral pneumonia of unknown origin has so far infected nine people in northern Argentina, of which three They have died and two are hospitalized in serious condition. The health authorities of the South American country have ruled out that it is covid-19 and the flu, among other viruses, and they still have not found what caused the infections in a private sanatorium in the province of Tucumán. One of the hypotheses that are being considered now is that it is a bacterial outbreak. The victim who died this Thursday is a 70-year-old patient who underwent surgery at the Luz Médica Sanatorium in San Miguel de Tucumán. Her death was added to that of a 68-year-old doctor and that of a 45-year-old nurse with comorbidities. According to the Tucuman Minister of Public Health, Luis Medina Ruiz, the last deceased could be “patient zero.” He began to show symptoms as of August 18, like five other employees of the sanatorium, of whom two are hospitalized, in serious condition and with mechanical ventilation. “Most of the patients began with vomiting, high fever, diarrhea, and body aches, with the evolution that in some patients was more complex”, explained Medina Ruiz at a press conference. Three other workers are under observation after beginning to show symptoms days later. “One of them is 40 years old and is hospitalized. She is a pharmacy officer and has a fever with bilateral pneumonia. Another person is a 44-year-old nurse, who is at her home. There is a 30-year-old male nurse with comorbidities. This patient was hospitalized today,” added the provincial minister. The health authorities await the results of the samples sent to the main infectious disease research institute in Argentina, Malbrán, to confirm the etiology of the outbreak. One of the hypotheses is that they have become ill from a bacterium called legionella pneumophila, which causes legionellosis or legionnaire’s disease, through the water distribution system. “If the original bacterium was called Legionella, we are talking about a known disease, the bacteria lives in water and resists extreme temperatures. It can be mild or in some patients severe. I don’t know how it spreads from person to person,” said former Minister of Health Pablo Yedlin. Even so, the experts are cautious and ask to wait for the results of the analyses, which are expected to be released tomorrow, Friday. Subscribe here to the EL PAÍS América newsletter and receive all the key information on current affairs in the region.