This picture released by Telam shows police officers standing at the entrance of the Luz Medica hospital, where nine people infected with bilateral pneumonia of unknown origin have been treated, in Tucuman, Argentina, on September 1, 2022. - A third person died this week in Argentina from pneumonia of unknown origin, local health authorities said on Thursday. Nine people in northwestern Tucuman province have been infected by the mysterious respiratory illness, including eight medical staff at the same private clinic, and three have died since August 29, Tucuman health minister Luis Medina Ruiz told reporters. Authorities are conducting tests on the illness but Medina said they have ruled out COVID-19, flu and influenza types A and B. (Photo by Diego ARAOZ / TELAM / AFP) / Argentina OUT / RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT "AFP PHOTO / TELAM / DIEGO ARAOZ" - NO MARKETING - NO ADVERTISING CAMPAIGNS

Authorities in Argentina are looking into the cause of several cases of severe pneumonia at a private clinic.

Three people have died so far, six other patients showed similar symptoms and were treated, the Tucumán Provincial Ministry of Health announced on Thursday.

Tests at the renowned Malbrán Institute for Covid-19, hantavirus and several strains of Legionella were initially negative. Further tests for various viruses and bacteria should follow.

“It’s way too early to speculate. Now we just have to wait for the diagnosis,” wrote the infectiologist Leif Erik Sander from the Charité Berlin on Twitter. “But the fact that medical staff is affected at least makes you sit up and take notice.” All those affected were employees or patients at the Luz Médica clinic in San Miguel de Tucumán.

Authorities in Tucumán reported the cases to the Pan-American Health Organization (Paho). Accordingly, the first patients complained between August 18 and 22 about fever, body and abdominal pain and shortness of breath.

Several of those affected were nurses. According to the Ministry of Health, all patients belonged to the risk group: they were smokers or had a history of respiratory diseases, obesity, diabetes and high blood pressure.