Animals that can carry plague bacteria found in the Western U.S.
The deer mouse is a potential source of diseases including the plague, salmonellosis and hantavirus.
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Often, humans become infected after being bitten by fleas that have bitten infected animals like deer mice and voles.
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Another easy way humans become infected is after their pet, mainly a house cat, hunts an infected rodent and then bites the owner or is host to infected fleas.
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The first known outbreak of plague in the United States came after infected rodents from China that were on ships mingled with urban rats in port cities. Los Angeles had an outbreak of plague in 1924.
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The California ground squirrel is highly susceptible to becoming infected with the plague and transmitting it widely to other squirrels.
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Rock squirrels are also highly susceptible to plague bacteria and can spread it widely among its species.
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Prairie dogs are some of the animals most affected by large die-offs after becoming infected with the plague.
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Scientists are testing vaccines to protect the black-footed ferret, an endangered species, from getting the plague. The species has experienced devastating losses from the plague over the years.
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California voles rarely come into contact with humans, since they are easily frightened, yet they can carry the plague and tularemia.
