Dear Doctor: My brother-in-law thought he had the flu, but it turned out to be Guillain-Barre syndrome. He’s now in his fifth month of an intense recovery. What can you tell me about the disease?

Dear Reader: Guillain-Barre syndrome is a rare disorder that affects about 1 in 100,000 people each year. It’s an autoimmune disease, which means the immune system goes a bit haywire. It mistakes cells within your body as threatening invaders and sets out to destroy them. In Guillain-Barre, the immune system attacks the peripheral nervous system, which encompasses all of the nerves in the body other than the brain and spinal cord. Infection with certain viruses and bacteria is a known trigger of Guillain-Barre, and is responsible for up to two-thirds of all cases.

Damage to the nerves results in weakness and exhaustion, often accompanied by tingling or pinprick sensations in the extremities. In the early stages of Guillain-Barre, people experience a loss of coordination that can impair balance, movement, speech, swallowing, vision and bladder control. These initial symptoms, along with possible abnormal blood pressure, both high and low, evolve over the course of the first few weeks. Progressive muscle weakness affects both sides of the body and occurs rapidly, often within hours or days. Severe cases of Guillain-Barre syndrome affect the patient’s ability to breathe and result in near-complete paralysis.

Diagnosis relies largely on a person’s symptoms. However, blood tests to measure red blood cells, white blood cells, platelets and hemoglobin, and metabolic panels to determine levels of electrolytes, blood sugar, total proteins and metabolic waste products, may be used to rule out other conditions. Guillain-Barre can cause certain changes to spinal fluid, so a lumbar puncture, also known as a spinal tap, may be ordered. Tests to measure nerve function can also be useful.

There is no known cure, so treatment consists of addressing existing symptoms, which is known as supportive care. This includes blood therapies such as plasma exchange, or plasmapheresis, which “cleans” the blood, or immunoglobulin therapy, which uses antibodies to try to calm the immune system. Patients often experience significant pain, which can be eased with medication. Since prolonged inactivity can lead to blood clots, compression garments and blood thinners are prescribed often. In serious cases, when swallowing or breathing are compromised, a feeding tube or a ventilator may be needed.

Most patients recover completely. However, as in the case of your brother-in-law, it’s often a gradual process. A lucky few are up and about in just a few months, but the majority of patients take about a year to fully recuperate. It’s also possible for recovery to take several years, and for patients to experience ongoing neurological issues.

Rehabilitative care includes physical, speech and occupational therapy. It can be a tough road back to good health, and many patients and their caregivers find a support group to be helpful. You can find more information at the Guillain-Barre Syndrome Foundation’s web site at gbs-cidp.org.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: I was a runner in college, but I stopped running after marriage and kids and work. I’m 62 now, and everyone says that if I resume running I’ll get hurt because I’m too old. What do you think?

Dear Reader: We believe it’s never too late to begin exercising and, with certain important caveats, this includes running.

Studies show that running offers a range of benefits to both physical and mental health. These include improvements to cardiovascular function, strength, endurance and bone health, as well as mood and cognition. An analysis of running studies conducted by British researchers published last year found that running as little as once a week was associated with increased longevity. A similar study published in 2017 found that runners reduced their risk of premature death by up to 40%. Several studies have associated running with an increase in metabolic markers associated with bone formation.

This potentially good news matters only if your approach to running matches your age and your fitness level. That includes taking into account muscle strength, balance, range of motion, heart and lung function, and any chronic health conditions you may have. Even if you are in great shape, your running life will be different today from how it was in your 20s. Based on your age, you’ll need to adjust your frequency, speed, intensity and mileage.

Since osteoporosis is a risk for post-menopausal women, and running is a high-impact activity, we believe it’s important get a bone density test. It’s a quick and painless scan that assesses bone health and can reveal any potential problems. It can also be a predictor of future injuries.

Also, please check with your health care provider before you get back to running. They can be a great resource to keep you strong and healthy, and to help track your progress. They can also make sure you’re being safe while getting back into running.

Do not try to do too much too soon. You’ve heard this before, but it really is important to ease in to your new activity. The most common running injuries, such as shin splints, stress fractures and Achilles tendon pain, arise from overuse. It’s tempting to set goals in terms of miles, but we recommend you think in terms of minutes. Begin by interspersing two or three minutes of gentle running (people used to call it jogging) with five or six minutes of running. Take a moment between cycles to stretch your quads and hamstrings, check your posture and control your breath. Give yourself a few months to gradually build up to a regular running schedule. Make sure to include strength and resistance training in your weekly exercise rotation, which will help prevent overuse injuries. Finally, finishing with gentle leg, hip and torso stretches will help your body recover and get you ready for your next run.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: I work in an open-plan office, and people aren’t good about staying home when they’re sick. Would wearing a surgical mask help keep me from catching someone’s cold or flu?

Dear Reader: It’s the height of our annual cold and flu season, so we understand your concern. Although the viruses responsible for respiratory illnesses are present year-round, they cause the largest numbers of illnesses in the winter months, when cold weather and short days keep people indoors. We spend a lot of time in close quarters, and in spaces that are often poorly ventilated. All of this makes it easier to transmit -- and to become infected by -- the viruses that cause influenza and the common cold.

Before discussing the pros and cons of a surgical mask, it’s useful to understand how viruses spread. A virus is a parasite that’s so tiny, it can only be viewed through an electron microscope. The influenza virus, for example, is 1,000 times smaller than a single grain of salt. It enters the body via the mucous membranes in the mouth, nose and eyes. Once inside a host, the virus injects its genetic material into a susceptible cell, hijacks that cell’s machinery and forces it to churn out millions of copies of the virus. The immune system promptly attacks the invaders, which causes the array of symptoms that make the flu such a misery -- fever, aches and pains, headache, exhaustion, coughing, sneezing and copious mucous production.

With every cough and sneeze, a sick person sends out a virus-packed aerosol mist that can travel 6 or 8 feet, bits of which can linger in the air for several hours. When a healthy person inhales the expelled droplets or picks them up from a contaminated surface and then touches their mouth, nose or eyes, they can become infected with the virus.

Unfortunately, when it comes to using a mask to protect against viruses, the evidence is mixed. Some studies, which focused on health care workers in hospital situations, found that masks can be effective at preventing infection when worn properly and used consistently. But the weave is too loose to filter all viral materials, and masks don’t always stay snug. Those same face masks may actually be more effective when worn by someone who is sick, since they block the spray of infectious matter from a cough or a sneeze.

If it makes you feel better, go ahead and wear a mask. But be sure to also follow additional precautions. Wash your hands frequently with soap and warm water, or use a hand sanitizer. Avoid touching your face since, as we mentioned, the mucous membranes of the nose, mouth and eyes are entry points for the virus. If you’re wearing a mask and then rub your eyes, you’ve defeated the purpose.

If you haven’t already done so, be sure to get a flu shot. Flu season typically peaks in January and February and lasts until the spring, so there’s still time for the vaccine to be helpful. And if you do get sick, please seek medical care.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)