Maryland health officials said Tuesday that an adult resident has died of rabies, the state’s first case of human rabies in nearly four decades.

Health officials said they did not know how the person was exposed to the rabies virus. To protect the privacy of the family, they provided no additional information about the individual or location of death.

In a statement, the Maryland Department of Health and Mental Hygiene said doctors and public health officials are assessing the risk of rabies exposure in people who had direct contact with the individual. When people are exposed to rabies, it is usually because of a bite from an infected animal, not from contact with another person.

The last case of human rabies was in 1976, the statement said.

Katherine Feldman, the state public health veterinarian, said the infection occurred in the past few weeks, and public health officials are trying to determine “who may have kissed the patient or anybody who had saliva contact” with the individual. “Thankfully, we don’t share saliva with a whole lot of people.”

The rabies virus is transmitted through saliva. Human rabies is prevented with rabies vaccine and rabies immune globulin, or preformed antibodies. Preventive treatment is only recommended for people with specific types of exposure to the saliva, tears, respiratory secretions or to fluid from the nervous system of an infected person.

During the past 10 years, on average fewer than five human rabies cases have been diagnosed each year in the United States. Among wild animals found to be infected with the virus are raccoons, foxes, skunks and bats. Unvaccinated dogs and cats can also become infected.

Maryland law requires all dogs, cats and ferrets to be vaccinated against rabies. Last year, 320 animals with rabies were detected in Maryland, and about 1,000 people in Maryland receive the preventive treatment each year after exposure through an animal bite, Feldman said.