'Walking pneumonia' mild but still needs to be treated

Q: My wife and I both had COVID-19. I recovered, but my wife kept feeling sick. We worried it might be long COVID. But when she saw her doctor, she got diagnosed with walking pneumonia. She took antibiotics and got better. How is walking pneumonia different from regular pneumonia?

A: Walking pneumonia is a term that is often used to describe a mild case of pneumonia. The medical term is atypical pneumonia.

The potential causes and physical symptoms of atypical pneumonia and “regular” pneumonia are basically the same. The difference between the two lies in the degree of illness. Someone with walking pneumonia can have symptoms that are so mild, they may not even realize that they are ill. Instead, they may think that they have somehow overexerted themselves, which has led to their feeling tired and rundown.

To understand pneumonia, let's start with the lungs. They are made up of a series of branching tubes that gradually go from large to small, like the trunk and branches of a tree. The smallest of these branches are known as bronchioles. Instead of leaves, though, bronchioles end in clusters of tiny and delicate air sacs known as alveoli. To give you an idea of how small these are, the average healthy adult has an estimated 480 million alveoli.

The alveoli, which are lined with capillaries, are where the oxygen that we breathe in passes to the blood and travels to sustain the tissues throughout the body. This is also where carbon dioxide, which our cells produce as a byproduct of metabolism, leaves the blood and exits via each exhaled breath.

When someone has pneumonia, it means that one or both lungs have become infected. While the most common cause is bacteria, viruses and fungi can cause pneumonia as well. It's not uncommon for someone whose immune system has been sapped by a viral infection to develop pneumonia as a secondary bacterial infection. The infection causes the alveoli to become inflamed, which results in the production of fluids or pus. These interfere with the gas exchange that supplies the body with oxygen and carries away carbon dioxide.

In regular pneumonia, symptoms typically include fever, chills, pain or pressure when coughing, a wheezing sound when breathing in, shortness of breath and fatigue or exhaustion. In so-called walking pneumonia, the major physical symptoms are either milder or, in some cases, not present at all. They can be confused for a cold or the flu. Some people report only feeling tired and rundown. This is because the buildup of fluid in the alveoli prevents adequate oxygen to get to the tissues of the body.

Diagnosis may include X-rays to look for fluid buildup in the lungs and lab tests to identify the pathogen. When bacterial, as in your wife's case, antibiotics are used.

Despite being a milder illness, walking pneumonia is serious. It's crucial to see a doctor and follow their treatment plan. Most people begin to feel better several days into their course of antibiotics; however, it's important to be patient and take it easy. Full recovery can take up to a month or more.

Can gut microbiome make you feel full?

Q: My boyfriend loves reading about the gut microbiome. He says there's new information that feeling full after you eat has to do with your gut microbiome. I always thought it was just because your stomach gets filled up with food. Is it actually the gut where feeling full happens?

A: We join your boyfriend in being fascinated by the ongoing discoveries about the gut microbiome. For anyone who isn't yet familiar, the term “gut microbiome” refers to the trillions of microorganisms that make their home in the digestive tract. The vast majority of these — about 90% — are bacteria. Other types of single-celled organisms, as well as fungi and viruses, make up the other 10%.

As research into the gut microbiome continues, the scope of its influence on our bodies, and on our bodily functions, becomes increasingly clear. The microflora in our bodies are involved in nutrition, metabolism, physiology and immune function. That means they play a key role in our physical, emotional and mental health.

It has also become evident that the gut microbiome is involved in signaling other organs and areas of the body. This occurs via a mechanism known as the gut-brain axis, which we have touched on in previous columns. And that's what leads us to your intriguing question about the gut microbiome and hunger.

Feeling full after eating is also known as satiety. As your boyfriend has mentioned, a recent study published in the journal Trends in Endocrinology and Metabolism links these feelings of satiety to the activity of the gut microbiome. It echoes similar findings in previous research, but by highlighting studies that focused on human rather than animal models, this new study adds weight to existing theories that link the gut to satiety.

Research into feeling full after a meal has honed in on small molecules known as short-chain fatty acids, or SCFAs, produced by the communities of microbes living in the gut. These molecules have been shown to play a role in the release of leptin, a hormone that regulates appetite and produces feelings of fullness.

SCFAs are a byproduct of fermentation, which is how our friendly gut microbes “digest” the insoluble fiber in our diets. That's the fiber that survives the initial process of digestion; it moves into the colon and acts as food for the gut microbiome. This new study identified several additional compounds produced by the gut during fermentation, which also play a role in signaling the brain with feelings of fullness.

More significantly, by focusing on studies in humans, it offers an expanded picture of the digestive process, which includes multiple avenues of direct communication between the gut and the brain. All of this adds to the importance of a diet that is high in quality sources of fiber. By eating from a wide range of fresh vegetables, leafy greens and fruits, you keep your gut microbiome happy and healthy. You also give it the tools to tell the brain that you feel full.

Non-Hodgkin lymphoma considered very treatable

Q: My grandfather is 72 years old and has been diagnosed with Non-Hodgkin lymphoma. I would like to know more about this type of cancer and what kind of treatment may be involved. Is it unusual for someone his age to get this kind of a diagnosis?

A: Lymphoma is a type of cancer that originates in the lymphatic system, most often in the lymph nodes. These are small pea- or bean-sized tissues that, along with a network of vessels, ducts and other structures, make up the lymphatic system. They work together to circulate a specialized fluid known as lymph. You know when you have a scrape and there's a layer of clear, watery fluid oozing from the wound? That's lymph.

Just as the job of the circulatory system is to transport blood, the lymphatic system carries lymph throughout most of the tissues of the body. It carries away cellular waste and helps maintain optimal fluid balance in the tissues. The lymphatic system is also part of the immune system and plays an important role in fighting infection and disease.

When someone has lymphoma, it means that certain types of white blood cells found in lymph, known as lymphocytes, have begun to grow out of control. Their abnormal behavior leads to the formation of tumors. These not only interfere with the workings of the lymphatic system, but cancer cells from the tumors can spread to other parts of the body.

Lymphoma is divided into two types. One is Non-Hodgkin lymphoma, which is your grandfather's diagnosis. This type of cancer is more common in men than in women. Although it can occur at any age, most cases are diagnosed in people 60 and older. A family history of the disease increases someone's risk. Certain chemicals and drugs, including insecticides and some types of chemotherapy, are also suspected to play a role.

The other type of lymphoma, known as Hodgkin lymphoma, is not as common. It involves a different subset of lymphocytes and is treated differently from Non-Hodgkin lymphoma.

Both types of lymphoma have similar symptoms. These include fatigue; unexplained weight loss; enlarged lymph nodes in the neck, armpits or groin; night sweats; and itching that can become severe.

Non-Hodgkin lymphoma can progress at different rates. A slow-growing cancer that has few symptoms is known as indolent. With this diagnosis, a treatment approach known as “watchful waiting” is sometimes recommended. It's just as it sounds — keeping a close eye on disease progress and not starting treatment unless symptoms begin to change.

When lymphoma spreads quickly and has signs and symptoms that can be severe, it is characterized as aggressive. Aggressive lymphoma requires immediate treatment. The approach depends on the stage at which the cancer is diagnosed, the patient's medical history and their general health. Treatment can include chemotherapy, immunotherapy, radiation and targeted drug therapy. In some cases, stem cell or bone marrow transplants may be recommended. These are arduous treatments and can have serious side effects.

Still, although it depends on the type and stage of the cancer, with a five-year survival rate of 74%, Non-Hodgkin lymphoma is considered very treatable.

• Dr. Eve Glazier is an internist and associate professor of medicine at UCLA Health. Dr. Elizabeth Ko is an internist and assistant professor of medicine at UCLA Health. Send your questions to askthedoctors@mednet.ucla.edu.