Argentina's Mystery 'Pneumonia' of Unknown Origin: Known Viruses Ruled Out

Cases of a mysterious pneumonia of unknown origin that has killed three people have been reported in Argentina.

Experts are rapidly researching what could be causing it and have so far ruled out known viruses such as COVID-19.

According to the World Health Organization (WHO), nine cases of the mysterious disease have been reported so far. Of those infected, eight were health care workers and one was an ICU patient. So far all the cases have stemmed from the same health care clinic in Tucumán. When the illness emerged, the clinic was shut down for seven days.

Pneumonia is an infection that causes air sacs in the lungs to fill with fluid. It can be life threatening, particularly in vulnerable individuals. The cases of pneumonia detected in Argentina are bilateral, meaning both lungs were affected.

Certain types of virus, bacteria and fungi can all cause pneumonia.

But so far, experts have not managed to find out what is causing the cases in Argentina. They are becoming increasingly concerned as tests for known causes have all come back negative.

COVID-19 and several types of flu have been ruled out, Tucumán Health Minister Luis Medina Ruiz said at a press conference on September 1. Experts also tested for legionella, a bacteria that can cause severe pneumonia cases. Again, this came back negative.

"What these patients have in common is the severe respiratory condition with bilateral pneumonia and compromise in images very similar to COVID, but that is ruled out," Ruiz said.

Severe cases of COVID-19 can cause pneumonia. This happens when the body's immune system attacks the virus when it settles in the lungs, causing air sacs to fill with fluid.

Connor Bamford, research fellow in virology and antiviral immunity at the Wellcome-Wolfson Institute for Experimental Medicine, told Newsweek that there's "very little information known at the minute," about the cases in Argentina and this is worrying.

"[It's concerning] over and above the current fatalities—if it turns out to be caused by a previously unknown virus, which is possible. What is of immediate concern is that this appears to be a serious infection associated with severe pneumonia [and] death in a close group of people; that it may be spread from person-to-person, and that we don't yet know what is causing it and therefore can't specific track or treat it," he said.

"Globally, we need to be better prepared to deal with novel viruses rapidly and effectively, and prevent them becoming devastating pandemics like COVID."

The ICU patient had been in hospital for a gallbladder problem at first, Ruiz said. During her treatment, she came down with the pneumonia at around the same time the other pneumonia patients displayed symptoms.

"At first she was considered patient zero, but she is under study based on the deepening of the analyses that are being carried out," Ruiz said. "This situation is unpredictable."

The WHO is continuing to monitor the situation as it unfolds.