Four people received donated organs from a man unknowingly infected with rabies, leading to a rare human death more than a year later that has authorities scrambling to treat the other three patients, U.S. health officials say. 

The man who died lived in Maryland and had received a kidney. The recipients of the donor's other kidney, heart and liver are getting anti-rabies shots, the federal Centers for Disease Control and Prevention said in a news release Friday. Those patients live in Florida, Georgia and Illinois.

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At the time of the organ donor's death, rabies was not suspected, the U.S. Centers for Disease Control said. (Fabrizio Bensch/Reuters)

The donor died in Florida in 2011 after moving there from North Carolina.

The CDC said it's working with public health officials and medical facilities in all five states to identify people who were in close contact with the donor or the four organ recipients. Those people might also need treatment, the agency said.

The Maryland patient's death more than a week ago prompted an investigation by state health officials that led to the announcement Tuesday of the state's first human death from rabies since 1976. Such deaths are rare, with typically just one to three cases diagnosed per year in the U.S., the CDC said.

The investigation revealed that the Maryland recipient had no reported animal exposures, the usual source of rabies transmission to humans. Investigators then confirmed that both the Maryland recipient and the Florida donor had died from the same type of raccoon rabies virus, the CDC said.

This type of rabies virus can infect not only raccoons, but also other wild and domestic animals. In the United States, only one other person is reported to have died from a raccoon-type rabies virus, the CDC said.

The organ transplants occurred more than a year before the Maryland recipient became ill and died, a period much longer than the typical rabies incubation period of one to three months. There have been other cases of such long incubation periods, however, the CDC said.

The donor died at a Florida medical facility. At the time of the donor's death, rabies wasn't suspected as the cause and testing for rabies was not performed, the CDC said. Rabies was only recently confirmed as the cause of death after the current investigation began in Maryland, the agency said.

Human rabies is rare in Canada, according to the Public Health Agency of Canada. Since 1924, 24 people in six provinces have died of rabies, the agency's website says.