Vampire bat bites man: Rabies transmission reported as U.S.’ first

The first reported case of human rabies linked to a vampire bat was reported today by the Centers for Disease Control and Prevention. The case, which happened about a year ago, resulted in the death of a 19-year-old man from Mexico.

In the CDC’s Morbidity and Mortality Weekly Report, the case went down this way: The man’s mother said her son had been bitten on the heel of his left foot while he was sleeping. The man, who has living in Michoacán, Mexico, apparently never reported the bite or was treated for it. Ten days later he traveled to Louisiana to work at a sugarcane plantation, where after one day of work he got medical help for a variety of symptoms, including fatigue, pain in his left shoulder and numbness in his left hand.

The man’s symptoms persisted, and while being treated at a hospital a spinal tap revealed a slightly elevated white bloodcell count and he was admitted to the intensive care unit, as doctors suspected he might have Guillain-Barré syndrome (an autoimmune disorder that can cause nerve damage).

Things got worse from there: The man developed a fever of 101.1 and had respitatory problems, then his pupils became fixed and dilated, his white cell count jumped and an EEG showed encephalitis. Tests for various diseases including HIV, syphilis and Lyme disease came back negative, but health officials suspected the root of the problem was rabies, although no animal exposures to the disease were known about at the time.

After doctors made a definitive diagnosis of rabies the man died. The 15-day incubation period was far shorter than the average 85-day period that had been noted in other human rabies cases in the U.S. Those who came in contact with the man both in the U.S. and Mexico were contacted and told of the exposure risks.

An editorial accompanying the report notes that although this is the first case of human rabies in the U.S. linked with a vampire bat, bat rabies viruses have been associated with most of the human rabies cases acquired in the U.S. for the past 20 years. In Latin American vampire bats have been the No. 1 cause of human rabies in the last 10 years.

Some research indicates that this may mean those Latin American bats are heading north as a result of climate change, and by expanding into the U.S. more humans and animals could be at risk for exposure. In addition to rabies, the authors say that bats could potentially carry other infectious diseases. That makes a case for more public education about rabies risk and how to avoid the creatures.

Scientists continue to study the animals. A study released online this month in the journal Nature found that vampire bats have developed heat sensors that help lead them to their prey.