A MYSTERIOUS flu-like illness has landed dozens of seemingly healthy people in hospital following an outbreak eerily similar to the early days of Covid.
Sixty people are receiving critical care after falling ill with "severe atypical pneumonia" in Buenos Aires, Argentina.
An alert about the suspicious cluster of cases was posted on Tuesday on disease outbreak monitoring network ProMED - the same used to flag the start of the Covid-19 outbreak in late December 2019.
Submitted anonymously by an "individual known to ProMED", the alert said: "In the past 30 days there appears to have been an increase in severe atypical pneumonia requiring critical care in Buenos Aires.
"The affected individuals are mostly young people without major risk factors."
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Some of the sick patients required machine ventilation to help them breathe.
Argentinian health officials have not made any official statements so details on the actual illness remain unknown.
But the alert suggested a third of sick patients showed signs of psittacosis, caused by a type of chlamydia which is rife in birds.
Many of the patients, however, have no history of contact of handling birds, the alert says.
How concerned should we be?
Global health expert Dr Michael Head, from the University of Southampton, told Sun Health: "There is so little information available about this outbreak that it’s impossible to gauge how worried, if at all, we should be.
"The world sees many outbreaks of pneumonia where often we don’t know the cause or the pathogen involved, and these are typically brought under control by the local public health agencies."
He added: "An important factor to know would be whether these patients were in the same location, for example, a place of work where they may have been exposed to infected bird faeces.
"If the epidemiology tells us that a likely scenario would be multiple cases of human-to-human transmission of psittacosis, this would be much more concerning than an initial source of infection common to all cases."
What is psittacosis?
Psittacosis - also known as Parrot fever - is a flu-like illness caused by contact with infected birds that can leave people suffering with severe pneumonia or brain and heart inflammation.
Five European countries have seen a sudden increase in parrot fever infections in recent months, the World Health Organisation (WHO) warned in an alert, though infections have been ticking up steadily over the past few years.
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Latest UK Health Security Agency (UKHSA) figures show six laboratory-confirmed cases of psittacosis in England in 2023.
In Britain, parakeets, the country’s only wild parrot species and a popular household pet, could pose a particular threat due to their vast numbers.
The new alert added: "Although psittacosis appears to be the etiology of some of the cases, there may be more than one agent involved.
"ProMED would appreciate more information about these cases."
The WHO said most people infected with psittacosis had been exposed to wild or domestic birds.
Symptoms of parrot fever tend to be mild and resemble the flu, with sufferers experiencing fever and chills, headache, muscle aches and dry cough.
But if left untreated, the illness can progress to severe pneumonia, inflammation of the heart called endocarditis, hepatitis and even brain swelling, according to the Centers for Disease Control and Prevention (CDC).
Prompt antibiotic treatment is needed to avoid complications from psittacosis, the WHO noted.