[Acute Necrotizing Pneumonia in Blue Tits - Implications for Pulmonology in Dialogue with Veterinary Medicine]

At the beginning of March 2020, observations of an increasing number of dead blue tits increased. The sick tits suffered among others from respiratory symptoms. The reason for the mass extinction initially remained unclear. By the beginning of May, around 18,000 reports of suspected blue tit deaths with around 33,000 affected birds had been received. The maximum was almost 1,300 reports on April 10^th. The number of reports decreased again during the following weeks. According to estimates, about 1,7 million blue tits died in Germany during this time.In a large number of the tits examined, the bacterium Suttonella ornithocola was detected in the lungs.Since the pathogen causes pneumonia, transmission via aerosol or through contact with infected secretions is to be assumed.Autopsies showed lung congestion, bloody intestinal contents and poor nutritional status. Histologically, mild to moderate acute necrotizing pneumonia was found. Since Suttonella ornithocola was also found in the parenchyma of the large organs, an additional acute sepsis can be assumed. Suttonella ornithocola could also be an intestinal pathogen, since Suttonella ornithocola was found in the intestine in addition to bloody intestinal contents, but at the same time no recognized intestinal pathogens were detected. The faeco-oral route of infection is therefore also possible.