The Illinois Department of Public Health (IDPH) said in a statement that the Lake County man, in his 80s, declined to start post-exposure rabies treatment after the August incident.
A month later, the man started experiencing symptoms of rabies and subsequently died.
The bat tested positive for rabies and a bat colony was later found in the man’s home.
The U.S. Centers for Disease Control and Prevention (CDC) says that rabies only affects mammals and is a preventable viral disease most commonly transmitted through the bite of a rabid animal including bats, raccoons, skunks and foxes.
Pets can also get rabies, though nearly all pets that have gotten rabies had not received a vaccination or were not up to date on vaccination.
The virus infects the central nervous system, ultimately causing disease in the brain and death.
In the U.S., more than 90% of reported cases of rabies in animals occur in wildlife and only one to three cases are reported in people annually, though approximately 55,000 Americans get post-exposure prophylaxis (PEP) each year to prevent rabies infection after being bitten or scratched by an infected or suspected infected animal.
Seven out of 10 Americans who die from rabies in the U.S. are infected by bats – the leading cause of human rabies death in the country, according to the agency.
In Illinois, bats are the most common species to carry rabies and at least 30 bats have tested positive for rabies in the state this year.
The rabies virus is transmitted through direct contact with saliva or brain or nervous system tissue from an infected animal.
While bite and non-bite exposures could theoretically transmit rabies, no such cases have been documented.
Casual contact with a person with rabies or contact with non-infectious fluid or tissue is not associated with risk for infection.
In addition, the rabies virus becomes noninfectious when it dries out or is exposed to sunlight.
Rabies symptoms in animals can vary, but are often similar to those in humans.
After exposure, the virus has to travel to the brain before symptoms occur, in what the CDC calls an “incubation period” that can last for weeks to months depending on the location of the exposure site, the type of virus and any existing immunity.
Initial rabies symptoms appear similar to the flu, including weakness, discomfort, fever or headache.
Itching or prickling at the site of the bite or exposure can progress to acute symptoms of cerebral dysfunction, anxiety, confusion, agitation, delirium, abnormal behavior, hallucinations, hydrophobia and insomnia.
The most severe period of disease typically ends after two to 10 days and the disease is almost always fatal.
Fewer than 20 cases of human survival from clinical rabies have been documented to date and only a few survivors had no history of pre- or post-exposure prophylaxis.
Worldwide, rabies causes approximately 59,000 deaths each year.
All bites or scratches should be immediately washed with soap and water and those who are bitten or scratched are encouraged to talk to a health care provider about whether they need postexposure prophylaxis.
Fox News’ Bradford Betz contributed to this report.