Rats Carry New Bacteria

Since the early 1990s, more than 20 species of Bartonella bacteria have been discovered. They are considered to be emerging zoonotic pathogens, because they can cause serious illness in humans worldwide from heart disease to infection of the spleen and nervous system.

"A new species called Bartonella rochalimae was recently discovered in a patient with an enlarged spleen who had travelled to South America," said Professor Chao-Chin Chang from the National Chung Hsing University in Taiwan. "This event raised concern that it could be a newly emerged zoonotic pathogen. Therefore, we decided to investigate further to understand if rodents living close to human environment could carry these bacteria."

Scientists have found that rodents carry several pathogenic species of Bartonella, such as B. elizabethae, which can cause endocarditis. Although scientists are unsure about the main route of transmission, these infections are most likely to be spread by fleas. A flea that lives on bank voles was shown to transmit different species of Bartonella bacteria. These pathogens have also been found in fleas that live on gerbils, cotton rats and brown rats.

"We analysed bacteria found in Rattus norvegicus in Taiwan. The brown rat is also the most common rat in Europe," said Chang. "By analysing the DNA of the bacteria, we discovered a strain that is most closely related to B. rochalimae, which has been isolated recently from a human infection in the United States".

The researchers took samples from 58 rodents, including 53 brown rats, two mice and three black rats. Six of the rodents were found to be carrying Bartonella bacteria; five of these were brown rats. Four of the rodents were carrying B. elizabethae, which can cause heart disease in humans, and one of the black rats was found to be harbouring B. tribocorum. However, the scientists noticed one strain that had not been identified in rodents previously. The strain was finally shown to be close to B. rochalimae.

MEDICA.de; Source: Society for General Microbiology