How can I protect my children against the enterovirus?

DEAR DOCTOR K: I'm very worried about the new enterovirus I'm hearing about. What can I do to protect my kids against it?

DEAR READER: Enterovirus D68 is a virus causing an epidemic of respiratory infections. It has been spreading across the news and across the country, making some children quite ill. Infection with the virus can cause nothing more than a garden-variety cold, but sometimes it can lead to serious breathing trouble, particularly for kids with asthma or a history of wheezing.

What should I look for in a toothpaste?

DEAR DOCTOR K: I'm confused by the many types of toothpaste on pharmacy shelves. What should I look for in a toothpaste?

DEAR READER: To prevent cavities and tooth decay, you need to brush away plaque -- that sticky, bacteria-laden material that builds up on teeth. It's best to brush at least twice daily, once after you eat breakfast, and then again before you go to sleep. When it comes to plaque removal, your toothbrush does most of the heavy lifting.

Should I participate in a research study?

DEAR DOCTOR K: I have a particular disease. A nearby medical school is recruiting people with my condition to participate in a research study. Should I volunteer?

DEAR READER There are two good reasons to consider volunteering for a study: It might help you, and it might help others. In some types of studies, there also may be risks to you. Sometimes my patients ask me: "Do we really need to do all these medical research studies?

Are there official guidelines for prostate cancer screening?

DEAR DOCTOR K: I've heard so many conflicting opinions about whether or not to get screened for prostate cancer. Are there official guidelines? What do they recommend?

DEAR READER: To say that prostate cancer screening has been controversial is an understatement. I spoke to my colleague Dr. Marc Garnick, clinical professor of medicine at Harvard Medical School, to hear his thoughts. The two ways to screen for prostate cancer are the digital rectal exam (DRE) and the prostate-specific antigen (PSA) blood test.

What exactly are e-cigarettes? Are they safe?

DEAR DOCTOR K: I caught my son and his friends smoking e-cigarettes. My son tells me I have no reason to worry, and that they're safer than regular cigarettes. What exactly are e-cigarettes? Are they safe?

DEAR READER: E-cigarettes are battery-operated devices that look like cigarettes. They are built around a heating element, a cartridge that contains nicotine and other chemicals, and an atomizer that converts the chemicals into a vapor. Instead of inhaling smoke from e-cigarettes, the user inhales this vapor. (This is sometimes called "vaping.")

What will help my sinus headaches?

DEAR DOCTOR K: I'm a woman in my 30s who has suffered from sinus headaches for years. Allergy medications haven't helped. What else can I try?

DEAR READER: Seasonal allergies can cause sinus congestion, sneezing and a runny nose. But when you experience pain and pressure in your head, it may be time to consider other causes. That's because sinus problems do not usually cause headaches. At least, they don't cause what most people refer to when they use the term "headache." Most people with sinus congestion refer to "head congestion," not headache.

What’s the health impact of gum disease?

DEAR DOCTOR K: Why is it important to keep my gums healthy? What are the consequences of gum disease?

DEAR READER: Gum disease can harm more than just your mouth; it can affect your overall health. Before describing why, I need to explain what gum disease is. Gum disease, or periodontal disease, is the primary culprit in adult tooth loss. It occurs when plaque -- the sticky, bacteria-laden film that collects on your teeth -- grows out of control. Gum disease begins when plaque forms in a shallow trough where the gum meets the tooth.

Will a digital fitness monitor help me become more active?

DEAR DOCTOR K: I'd like to be more active. Do you think a digital fitness monitor will help?

DEAR READER: When digital fitness monitors (DFMs) became available several years ago, I was initially skeptical. I figured they would be the latest example of our fascination with electronic devices and that people would quickly tire of them. Well, surveys show that some people have quickly tired of them and left them to collect dust in a drawer.

Will steroid shots relieve spinal stenosis pain?

DEAR DOCTOR K: I have spinal stenosis. Will steroid shots help with pain relief?

DEAR READER: Spinal stenosis is a narrowing of the open space in the spinal canal. This squeezes nerves, causing pain in the lower back, buttocks and legs. I have spinal stenosis, so I know about it both as a physician and a patient. Medicines and physical therapy are usually the first treatments for spinal stenosis pain.

I’m a woman in my mid-50s — what could cause my decline in sexual arousal?

DEAR DOCTOR K: I'm a woman in my mid-50s. Lately I haven't been able to become sexually aroused. What could be wrong?

DEAR READER: Sex is complicated. You probably already know that. Sexual desire surely resides in the head, but other parts of the body can affect desire as well. In particular, the genital organs communicate with the brain. Likewise, the brain communicates with the genital organs. Desire in the brain causes changes in the pelvic organs. Perceiving these changes can, in turn, enhance sexual desire.