Lincoln Park Zoo said the specific source of the exposure of the animals to bird flu, or H5N1 virus, is not known.

Officials at Lincoln Park Zoo confirmed Wednesday that a harbor seal and a Chilean flamingo each died of highly pathogenic avian flu earlier this month. In a statement, zoo officials said the

Current strains of bird flu are “poorly suited for pandemic potential,” said Dr. Shira Doron, a Tufts Medicine infectious disease expert.

The first person in the U.S. just died from a strain of the virus in Louisiana, but there’s still some simple ways to stay safe.

The bird flu, which seemed to be fading away, has once again set off alarms. With the first death recorded in the United States and the virus detected in every state, the situation is becoming increasingly complex.