"We thought that wild birds were incubators for salmonella, but have now found that garden birds carry two strains of a group of salmonella microorganisms called Salmonella Typhimurium, itself only one of over 2,500 types of Salmonel," said Paul Wigley, from the National Center for Zoonosis at the University of Liverpool. "We screened salmonella genes we knew to be involved in causing disease and found they lacked a gene normally found in the human form of the infection."

He said the finding suggests the infection will keep circulating in the same species, increasing the risk of further disease outbreaks.

"We now know that these salmonella strains are not resistant to antibiotics, but it would be inadvisable to use antibiotics in garden birds as this would inevitably lead to the development of antibiotic resistant bacteria within these populations," said Wigley.

The research appears in the journal Veterinary Research.