U.S. records its first human bird flu death

The U.S. has recorded its first human death from bird flu, a grim milestone that comes as at least 66 cases have been recorded in the country.

The patient, who was over 65 and had underlying medical conditions, was hospitalized in Louisiana in December; the case was considered the country’s first severe human H5N1 infection.

The Louisiana Department of Health said the patient had been exposed to a combination of a backyard flock and wild birds. 

“The Department expresses its deepest condolences to the patient’s family and friends as they mourn the loss of their loved one,” it said in a statement. “Due to patient confidentiality and respect for the family, this will be the final update about the patient.”

All but one of the human bird flu infections confirmed so far in the U.S. were diagnosed in the last 10 months, according to the Centers for Disease Control and Prevention. Most cases have been relatively mild, with symptoms including pinkeye, coughs or sneezes.

The majority of the patients became sick after exposure to infected cattle or poultry. The Louisiana patient was the first case linked to exposure to a backyard flock.

Public health officials have not found any evidence that the virus has spread person-to-person, which would mark a dire step in bird flu's evolution. However, samples of the virus collected from the Louisiana patient showed signs of mutations that could make it more transmissible to humans, according to the CDC.