Guillain-Barre syndrome is a condition in which the body’s immune systems attack its nerves, often after infection with a respiratory bug or stomach flu.

Although acute cases are an emergency, most people recover completely, according to the Mayo Clinic.

Q: What are its symptoms?

A: While its first symptoms are usually weakness and numbness in the extremities, it can eventually paralyze the entire body, according to the Merck Manual of Medical Information. Symptoms are often worst in the first two or three weeks.

In 5% to 10% of cases, the muscles that control breathing become so weak that patients need to be put on a ventilator. In another 10% of cases, muscles that control swallowing are so weakened that patients need to be fed through a tube into the stomach.

Q: How is it treated?

A: Doctors may cleanse the blood, removing harmful antibodies, or give patients a treatment called immune globulin, with protective antibodies with donors, according to the Mayo Clinic.

Q: Do people recover?

A: Most patients improve slowly over several months, even without treatment, according to the Merck Manual. Early treatment can speed up recovery, allowing patients to improve within days or weeks. Although there’s no known cure, treatment can ease recovery, according to the Mayo Clinic.

About 30% of adults still suffer from some muscle weakness three years later, however. Fewer than 5% of patients die in the early stages of the disease.

Q: How common is it?

A: Guillain-Barre affects one or two out of every 100,000 people.

Q: What causes it?

A: Doctors don’t know the exact cause of Guillain-Barre, and some cases appear without any clear trigger, according to the Mayo Clinic. One of the most common triggers is campylobacter, a type of bacteria often found in undercooked chicken or other food. Guillain-Barre has also been triggered by surgery; the Epstein-Barr virus; Hodgkin’s disease; mononucleosis; HIV, the virus that causes AIDS; and rabies.

In an infamous outbreak in 1976, hundreds of people who received a swine flu vaccine developed Guillain-Barre, although scientists question whether the shots were really the cause. The Centers for Disease Control and Prevention has not seen any increase in Guillain-Barre related to vaccination against the H1N1 virus.

Q: How is the immune system involved?

A: The disease occurs when the immune system — which typically protects the body from illness by attacking viruses and other foreign invaders — instead attacks the myelin sheath, a coating that protects the nerves. Damage to this critical coating, which acts like insulation, interferes with the way that nerves send signals between the body and brain, according to the Mayo Clinic.