But there is the risk of an asthma attack in some susceptible people, he said.

A simpler blood test could be included as part of routine physical examinations to counsel susceptible people about their increased risk.

It can cause death or injury in susceptible people, particularly people with weakened immune systems.

It is often seen in people already susceptible to allergies and/or asthma.

A small number of medical centers now perform a laboratory test to identify susceptible people among affected families.

Yet too much stress, or chronic stress may lead to major depression in susceptible people.

When the stress response fails to shut off and reset after a difficult situation has passed, it can lead to depression in susceptible people.

Suffering from pain for extended periods of time leaves many people susceptible to depression.

"Once an idea that a place is haunted takes hold with susceptible people, things are no longer accidental," he said.

Side effects can include rapid pulse, sweating, and anxiety reactions in susceptible people.