Wild birds might not be the culprits after all
Salmonella bacteria in wild birds are sensitive to antibiotics, a study has found, unlike the increasingly resistant strains found in livestock and humans. The finding suggests that wild birds carry a distinct population of the bacteria, and may not be responsible for infecting livestock, as was previously thought. 
Photo: Matteo Di Nicola
Scientists believed that wild birds carried a variety of Salmonella strains, and passed these on to livestock through their feces. However, researchers at the University of Liverpool, UK, found that only two strains were common in the wild birds that they studied, neither of which is prevalent in livestock or humans.
Dr Paul Wigley of the university's National Center for Zoonosis said: "We thought that wild birds were incubators for Salmonella but have now found that garden birds carry two strains of Salmonella typhimurium, itself only one of 2,500 types of Salmonella. We screened Salmonella genes we knew to be involved in causing disease and found that they lacked a gene normally found in the human form of the disease.
"The work suggests that 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. We also now need to explore other possible sources to understand the infection in livestock and humans."
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