Fungal meningitis epidemic targets human brains

Scientists are trying to understand more about the fungal meningitis outbreak in the United States that infected 419 people and killed 30, especially why it was so deadly.

The plant-eating exserohilum rostratum generalist prefers grasses but will eat multiple items, including humans. Glen Roberts, a retired medical mycologist, was shocked to learn the identity of the pathogen in the epidemic because human infections are so uncommon, Scientific American reports.

The contamination originated in three lots of an injectable steroid prepared within the admittedly filthy laboratory in the Framingham, Mass.-based New England Compounding Center. Scientists are putting together the pieces of how the fungus got into the lab and spread to the medication.

A combination of a messy laboratory, a warm summer and plentiful grass clippings could have easily gotten the fungus into the three batches of medication.

After the fungus was injected with the steroid into the epidural space of patients, the space between the dura mater and the inside walls of the vertebrae, the filaments of the fungus entered the spinal fluid and went straight to the brain.

"Spinal fluid is a great culture medium-one of the best," Roberts said, according to Scientific American. "The nutrients are there, and the temperature is certainly right."

The human immune system has a difficult time eliminating or controlling infection when it occurs in the brain.

The steroid drug itself may have been the source of the contamination. While the water used to create the final doses for the steroid was allegedly sterile, the steroid drug ingredient was not sterilized.

"Using nonsterile components (for injection) in somebody's spine?" Roberts said, according to Scientific American. "My goodness, that's terrible."

Why only three lots of the steroid were affected and not all of them remains a mystery, Scientific American reports.