Avian vacuolar myelinopathy (AVM) is a neurological disorder that has been killing bald eagles and other birds in the US after 25 years.

Scientists appear to have cracked the mystery of a neurological disorder that has been killing bald eagles and other birds in the United States after 25 years.

According to New Scientist, eagles might have consumed bromide-laced prey plucked from lakes. These species then developed a disease caused by a toxin released by blue-green algae from the lake.

Bald eagles died in large numbers in Arkansas in 1994. The predatory birds’ navigation abilities will deteriorate until death, forcing them to crash into trees or even losing their ability to fly.

Killer Plant Spreading Across U.S.

When their brains were analyzed post-mortem, scientists discovered distinct lesions and gaps inside, giving the impression that the disease had eaten the brain away.

The condition was eventually determined to have been contracted by the eagles from the waterbirds they preyed on, who also showed similar symptoms before dying. Experts named the disorder as Avian vacuolar myelinopathy (AVM).

For years, scientists believed AVM was contagious in some way, but the precise cause was unclear. More AVM outbreaks occurred along the way in the Southeastern United States, around lakes and other freshwater bodies. By the early 2000s, they had established a strong link between the spread of Hydrilla verticillata, an invasive aquatic species, and AVM.

Researchers discovered in 2015 that a particular photosynthetic bacteria called cyanobacteria that grows on this plant caused the AVM. The previously unknown species was given the name Aetokthonos hydrillicola, which means “eagle killer living on hydrilla” in Greek and Latin.

Cyanobacteria are also known as blue-green algae because of their color when clumped together in large numbers. Despite the nickname, they are not true algae. This type of algae is harmful to animals and humans because of the toxins it can create.

When scientists from the University of Georgia and other institutions attempted to examine A. hydrillicola in isolation, they discovered a problem. The bacteria they produced in their lab were harmless to birds. They seemed to be harmful only when they were growing on the vine.

Originally published at Science Times