Dear Doctor: I've been reading about a new illness that's a lot like polio and is making children in parts of the country very sick. What is it, and should my family and I be worried?

Dear Reader: You're referring to acute flaccid myelitis, also known as AFM, a rare neurological disease that affects the spinal cord. The symptoms mimic those of polio, which has helped to push AFM into the headlines.

Before we get into specifics, we want to stress that AFM is quite rare. Despite the sudden spate of alarming news reports that have, quite understandably, caused you concern, the rate of infection is extremely low -- one person per million. As of last November, there were 120 confirmed cases of AFM in the United States in 2016.

So what exactly is AFM?

It's a syndrome that can cause the muscles and reflexes in the body to stop working normally. Symptoms often arise quickly. What begins as a fever or respiratory illness gives way to weakness in the limbs, including a possible loss of muscle tone.

In several reported cases, the first symptom in a child diagnosed with AFM was a sudden limp. Some patients have slurred speech or facial drooping. In the most serious cases, acute weakness in the muscles that control breathing has led to respiratory difficulties.

At this time, the causes of AFM are not fully understood. Officials at the Centers for Disease Control and Prevention suspect a range of viruses may be involved. These include West Nile virus, enteroviruses that enter the body through the intestines, and adenoviruses, which can cause coldlike symptoms, including sore throat, bronchitis, pneumonia, diarrhea and pink eye.

Research into the causes of AFM, which affects children in greater numbers than adults, is a national priority. At the CDC, scientists and public health specialists are gathering blood samples as well as fluid specimens from the nose, respiratory tract and spinal cord of affected patients for testing. Results are collected into a database for study and analysis.

The symptoms of AFM are similar to several other conditions that are far more common. This has increased the challenge of arriving at an accurate diagnosis. However, awareness of the disease among health care providers is growing rapidly, which means that diagnosis and reporting are become more accurate.

If you believe you or your child has symptoms that correspond with those of AFM, call your family doctor. The findings from a careful examination of the nervous system, with accurate mapping of the muscles and reflexes affected, and diagnostic tests such as an MRI and analysis of the cerebrospinal fluid, will allow a correct diagnosis.

Several germs are suspected in AFM, so the CDC recommends that your family is up-to-date on polio and all other recommended vaccinations, and that you protect yourself and your family from mosquito-borne viruses by using insect repellents.

The good news is that increased awareness of AFM is leading to an ever-larger volume of reliable data for researchers to work with. That means more information about what causes the disease, and more avenues in which to seek and find a cure.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095.)

Dear Doctor: Does outlook really matter when it comes to lifespan, as a recent study suggested? I'm not a wet blanket, but I don't have a relentlessly sunny disposition either.

Dear Reader: Let's say it's a gray, cloudy Monday morning. You're stuck in traffic, listening to the news of another atrocity in some distant land. Such a scenario would not in itself arouse feelings of optimism. Instead, an optimistic person might focus on feeling excited about his or her job, realize that the traffic is going to get better, and take solace in the fact that humanitarian efforts will be made to stop further atrocities.

In my own experience, I've seen pessimistic, unhappy people lead very long lives, and I've seen optimistic people's lives cut short by illness. That doesn't mean that, in the aggregate, optimism has no effect on lifespan.

Specific studies have looked for correlations between an optimistic outlook and cardiovascular disease, finding mortality benefits among those who had a more optimistic attitude. These studies used different scales to judge a person's level of optimism, with one common approach using a questionnaire about a person's approach to life. Some, for example, asked people to respond in either agreement or disagreement to statements such as, "Overall, I expect more good things to happen than bad."

A combined evaluation of many studies assessing the connection between optimism and physical health was reported in the Annals of Behavioral Medicine in 2009. Researchers measured physical health outcomes by rates of cancer, heart disease, infection rates, pain, diabetes and kidney failure. In the combined evaluation, the authors found a small correlation between better physical health and optimism, and an even smaller correlation between lower death rates and optimism.

A more recent study published in 2016 in the American Journal of Epidemiology followed 70,000 nurses and judged levels of optimism by how they responded to a questionnaire called the Life Orientation test. The women responded to 10 different statements such as, "In uncertain times, I usually expect the best," "I rarely count on good things happening to me," and "I'm always optimistic about my future."

The researchers ranked women into four quartiles, from lowest to highest, and found that those who were most optimistic had a 26 percent decrease in the death rate over the study period compared to those who were the least optimistic. This was after adjusting for depression, because some people who aren't optimistic may actually be depressed. The decrease in death rates was seen for deaths caused by cancer, strokes, heart attacks and infections.

One problem with the study is that women who were the most optimistic had lower smoking rates, were more physically active, had more education and were more likely to be married. Each of these factors is associated with greater longevity. The authors say they adjusted for these factors, but fully adjusting for them is difficult. Another problem with the study is that the study might not reflect correlations within the general population, in that 97 percent of the women identified themselves as white.

Overall, the study found what appears to be a correlation between optimism and a better cholesterol level, higher blood levels of antioxidants and improvements in one's immune system.

My own feeling is that optimism is less about sunniness than about hopefulness. This hopefulness helps people get through the bad times, because they realize that good times are ahead. And, overall, such people seem to have healthier habits that can help lead to greater longevity.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095.)

Dear Doctor: I had toenail fungus two years ago, and my doctor prescribed Lamisil. It took a long time, but it worked. Now the fungus, which is so ugly, is back again. Why is it so hard to get rid of, and are there any new treatments available?

Dear Reader: Toenail fungus is fairly common, but that's not much consolation to the 6 million or so people in the United States who have to put up with it. It's an often-unsightly infection caused by a microscopic organism called a dermatophyte that lives beneath the toenail. More precisely, it colonizes the portion of the nail known as the matrix, which is underneath the cuticle.

Initial symptoms are a yellowish or brownish discoloration of the toenail. As the infection progresses, nails will often become thickened, crumbly and malformed. Although the fungus affects the appearance of the nails, it actually lives on the layer directly beneath the toenail. That's why it's so difficult to treat.

Your nails are made up of keratin, a tough, fibrous protein. The same hard shell that protects your toes is giving shelter to the fungus. For topical medications to be successful in killing the fungus, they have to be able to reach it.

Anti-fungal creams and liquids are available, both in over-the-counter preparations and by prescription. But because nails are not porous, it's difficult for the medication to reach the infection in concentrations great enough to kill the fungus. As a result, success rates for topical treatments are low.

Systemic medications, like the Lamisil your physician prescribed, take a more direct approach. You swallow the pill, it gets digested, and the medication enters your bloodstream. Your circulatory system delivers the medication directly to the fungus living beneath your toenail and, in the best-case scenario, kills it.

However, there are drawbacks. Side effects can include headache, nausea and diarrhea. In rare cases, the drug can cause liver damage, so blood tests to monitor potential toxicity are needed. These infections are quite persistent, and your experience with recurrence is fairly typical. Although oral medications are the most effective, reported failure rates are as high as 20 to 30 percent.

Nail growth is slow, which means treatment is a lengthy process. A big toenail can take anywhere from a year to 18 months for new growth to completely replace the old, infected nail. Oral treatment for toenail fungus generally lasts 12 weeks. Topical preparations must be applied for at least a year.

Nail fungus is not a health risk to most people. But anyone with a compromised immune system, such as a diabetic who contracts nail fungus, is at risk of developing serious complications like foot ulcers. Therefore, it's vital that diabetics seek medical treatment.

As for your question about new treatments, some physicians and podiatrists offer laser treatment of toenail fungus. Although some patients report good results, reliable data about the long-term efficacy of laser treatment is scarce.

Our recommendation is that you meet with your primary care physician, who will want to do a physical exam of the affected area. Then you can discuss the specifics of the recurrence and evaluate which of the existing treatments are best for you at this time.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095.)