Person Dies from Bat Bite: How Rabies Kills

A person in Florida has died from rabies after being bitten by a bat.

The individual died after a bat carrying the disease bit them and they did not immediately seek medical treatment, the Florida Department of Health confirmed yesterday (Oct. 31). A series of four doses of the rabies vaccine can protect people after they've been exposed to rabies, according to the U.S. Department of Health and Human Services, but only if they receive the first dose soon after they are exposed.

There's one big reason it's important to get vaccinated as soon as possible after a rabies exposure: The virus kills on its own schedule. Rabies' incubation period, or, the time it takes for symptoms to appear, depends in part on where on a person's body he or she is bitten or exposed to the virus, Dr. Amesh Adalja, an infectious-disease specialist and a senior associate at the Johns Hopkins Center for Health Security, told Live Sciencein June. (Adalja was not involved in the Florida case.) [27 Devastating Infectious Diseases]

Rabies enters the body through a bite wound, then picks its way along the long chains of nerve cells toward the central nervous system and brain, Adalja said. That journey can take anywhere from days to months, depending on where on the body the person was exposed. A bite on the face, for example, will have a shorter incubation period than a bite on the foot.

Once an infected person starts to experience symptoms though, they proceed in a predictable order, usually resulting in death, Adalja said.

First, a person will have symptoms typical of many viral infections, such as a fever and headache, Adalja said. Then, as the virus makes its way into the brain, the soft tissue of the brain becomes noticeably inflamed, disrupting the normal communications among neurons. That symptom, known as encephalitis, causes the famous personality changes associated with rabies: alterations in personality and thinking, agitation, delirium, and in some cases, hydrophobia, or fear of water. These severe symptoms tend to show up about two weeks after the first hints of a headache.

Eventually, all of that inflammation and disruption becomes too severe for the brain to survive, Adalja said. Patients experience seizures and slip into comas. The overwhelming majority of these individuals die.

But an infected individual can usually avoid this fate by seeking medical treatment immediately after being exposed to the virus. The rabies vaccine will almost always stop the virus in its tracks if administered before symptoms begin, Adalja said.

"If an exposure [to the rabies virus] occurred, it is important to administer treatment in a timely manner," the Florida Department of Health said in a statement emailed to Live Science.

Avoiding exposure in the first place is important as well. "Avoid direct contact with wildlife," the department said in the statement. "If you believe you may have been exposed to rabies, including any physical contact with a bat, contact your health care provider and your county health department right away."

Originally published on Live Science.