Three people have died of rabies in the United States in the past year, according to the Centers for Disease Control (CDC) and media reports, though only one case is suspected to have originated in this country.

A soldier at the Fort Drum Army base in New York State died last week, presumably from exposure to the virus while deployed as a cook with the 615th Military Police Company in Afghanistan, according to theWall Street Journal.

Photo by Alessandro Catenazzi via Wikipedia Vampire bats are a leading cause of rabies in Latin America.

The CDC reported in itsMorbidity and Mortality Weekly Report that a 70-year old Wisconsin man checked himself into a hospital emergency department in December 2010 after experiencing shoulder pain, difficulty swallowing, excessive sweating and tremors. The hospital initially diagnosed the man as suffering from alcohol withdrawal syndrome. After nine days of hospitalization and worsening symptoms, hospital staff discovered that the man had had contact with bats. His wife said he was selling firewood and bats were present in the woodpile, though he did not report being bitten.

On Day 11 of his hospitalization, a silver-haired bat variant rabies virus infection was confirmed in a test of his saliva. He died on Day 13.

The CDC also reported that a 19-year-old migrant worker from Mexico died of rabies while working on a farm in Louisiana. The case was remarkable because it was the first reported death in the United States from a vampire bat rabies virus variant. However, it was discovered that the man had been bitten by the bat while home in Michoacán, Mexico. He died after about three weeks.

The average incubation period for human rabies in the United States is 85 days, the CDC says, but the farm worker had an incubation period of only 15 days. The agency suggested that vampire bat rabies virus variants could have shorter incubation times than other variants.

According to the CDC, bats are the leading cause of rabies infection in humans.

"Bat rabies virus variants have been associated with the majority of indigenously acquired human rabies cases in the United States for approximately 2 decades," the CDC says. "Similarly, vampire bats have become the leading cause of human rabies in Latin America during the last decade."

Luckily, vampire bats do not currently live in the United States, but that could change.

"Although vampire bats currently are found only in Latin America, research suggests that the range of these bats might be expanding as a result of changes in climate," the CDC reports. "Expansion of vampire bats into the United States likely would lead to increased bat exposures to both humans and animals (including domestic livestock and wildlife species) and substantially alter rabies virus dynamics and ecology in the southern United States."