Dear Doctor: Is it true that dog treats made from pigs’ ears are giving humans a dangerous infection? I don’t buy them because, honestly, they look kind of gross, but our dogsitter brings them over sometimes. Should we be worried?

Dear Reader: You’re referring to a series of alerts issued by the Centers for Disease Control and Prevention about an outbreak of salmonella infections, which have been identified as being resistant to several different antibiotics. These infections have been tied to dog chews made out of pig ears.

As of the CDC’s latest update on July 17, a total of 93 people living in 27 states have become ill, including 20 individuals who had to be hospitalized. No deaths have been reported at this time. If you have these dog treats in your home, the CDC recommends wrapping them securely and disposing of them. Use hot, soapy water to wash anything that came into contact with the treats, including surfaces, containers and, of course, your hands.

Salmonella is a group of bacteria that cause about 1.2 million people to become sick each year. They can cause an illness known as salmonellosis, which develops as soon as 12 hours and up to three days after ingesting the bacterium. The infection often occurs when feces infected with the bacteria comes into contact with food or water and is unknowingly consumed. Symptoms, which include fever, abdominal pain and diarrhea, last from four to seven days. Although the majority of people recover without medical treatment, in some cases the diarrhea can be severe enough to require hospitalization.

The danger is that a salmonella infection can move from the intestines into the bloodstream, and then spread to other areas of the body. The infection is particularly risky for children under age 5, for the elderly, for individuals who are medically frail and for those with weakened or suppressed immune systems. Treatment typically focuses on managing diarrhea and pain, preventing dehydration and, if the infection has spread via the bloodstream, the use of antibiotics.

Pig ear treats are just the most recent source of a salmonella outbreak. In recent years, sources as diverse as pet guinea pigs, pet hedgehogs, dog food, papayas, sprouts, nut butters, backyard chickens, small turtles and chicken salad have been linked to outbreaks. In response to the current outbreak, Pet Supplies Plus, a distributor of bulk pig ears, which are stored in large, open bins, has agreed to a voluntary recall of the treats. At this time, pre-packaged pig ear treats from individual brands are not part of the recall.

Pets can also become ill from a salmonella infection. Their symptoms can include lethargy, diarrhea that may be bloody, vomiting and fever. Pets with salmonella infections may be sluggish, run a fever, begin vomiting and have diarrhea that may contain blood or mucus.

For the latest information on the current outbreak, visit cdc.gov/salmonella.

(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: Does insulin resistance increase as we age? I just read it has something to do with the gut. Why would that be true?

Dear Reader: To talk about insulin resistance, we should start with insulin. It’s a hormone produced by the pancreas that helps to make glucose available to the body, which uses it for energy. After you eat, as your body digests the food, glucose is released into the blood. The pancreas then releases insulin. This hormone makes it possible for muscle, fat and liver cells to absorb glucose. When your insulin metabolism is working properly, cells get the building blocks they need to produce energy, and the level of glucose in the blood remains within a healthy range.

One way things can go awry is insulin resistance. This means that even though the pancreas releases insulin into the blood, the fat, muscle and liver cells don’t respond properly to the hormone. This leaves too much glucose in the blood, which prompts the pancreas to release even more insulin. As long as the beta cells of the pancreas remain capable of producing the extra insulin that the muscle, fat and liver cells now need, blood sugar levels will remain in a healthy range. But once the pancreas can no longer keep up with the increased demand for insulin, the resulting extra blood glucose can lead to an individual developing Type 2 diabetes.

It’s estimated that up to 1 in 3 Americans, including half of people age 60 and up, experience insulin resistance. Last year, the results of a study published by scientists at the National Institute on Aging shed light on possible reasons for the link between age and insulin resistance. For answers, the researchers turned to the gut. Specifically, they became interested in the fact that despite differences in ethnicity, geographic location and the contents of their diets, people had similar changes to their gut microbiomes as they aged. One of these changes is a decrease in the healthy layer of mucus in the gut, which is needed for optimal production and absorption of nutrients. The health of this mucus layer relies, in part, on a specific beneficial bacterium known as Akkermansia muciniphila, or Akk.

While studying mice, and then rhesus monkeys, researchers found that aging was associated with a drop in levels of mucus-friendly Akk. This triggered a series of events that gave rise to certain immune cells, which were linked to insulin resistance. When levels of Akk bacteria were restored to normal, the insulin metabolism in the animals returned to normal as well.

The research is exciting because it opens up new avenues of inquiry into the problem of insulin resistance. It’s good news because Type 2 diabetes has already reached epidemic proportions around the world. Now, with a rapidly aging population, novel therapies to maintain a healthy insulin metabolism are more important than ever.

(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: Why is melanoma so dangerous? I had a squamous cell growth removed, and it was no big deal. However, a mole that had to be biopsied for melanoma (it turned out to be benign) has my doctor worried.

Dear Reader: We’re glad to hear your biopsy results came back negative for melanoma, and we can understand your doctor’s concern. Melanoma isn’t the most common skin cancer, but it is the most serious. This type of cancer can grow quickly and aggressively spread to other parts of the body. Although melanoma accounts for just 1% of all skin cancer diagnoses, it causes the majority of skin cancer deaths. Early diagnosis and treatment is crucial.

Skin cancer is the most common type of cancer, with about 9,500 new cases diagnosed each day. More people are diagnosed with skin cancer each year in the United States than all other types of cancer combined. Like all cancers, it occurs due to abnormal and uncontrolled cellular growth.

Squamous cell and basal cell carcinomas, the first- and second-most common types of skin cancer, are named after the types of skin cells from which they arise. They tend to grow slowly, and it is uncommon for them to spread. Melanoma arises from melanocytes, cells that produce a brown pigment called melanin. Researchers have discovered that unlike other cancer cells, which have to “learn” how to spread through the body, melanoma cells are equipped with a cellular mechanism that lets them start spreading immediately. That’s why this cancer is so deadly.

Risk factors for melanoma include a history of sunburn, excessive exposure to UV light, the use of tanning beds, having fair skin, a family history of the disease and having a large number of moles or certain types of unusual moles. Normal moles generally have a consistent color -- usually tan or brown -- and uniform borders. When moles change shape or color, become irregular, get crusty or bleed or grow larger, or when new moles or skin discolorations appear and change, it can be cause for concern. A mole that looks markedly different from the other moles on your body can also indicate something is wrong. These warning signs have been turned into a memory prompt, the “ABCDE rule”:

-- Asymmetry: The halves of a mole or birthmark don’t match.

-- Border: Edges are irregular, jagged or blurred.

-- Color: Color is irregular or patchy, sometimes with areas of red, pink, white or blue.

-- Diameter: Moles larger than 1/4 inch across, although melanomas can be smaller than that.

-- Evolving: A mole or birthmark that begins to change shape, color or size.

Studies show that regular sunscreen use can cut melanoma risk in half. Considering that the number of melanoma deaths is expected to increase by 22% in 2019, this bit of self-care can be a life-saver. Note and keep a record of the moles on your body and how they change. If you see any of the ABCDE characteristics, contact your doctor immediately.

(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.)