Infectious Diseases

Can you still have symptoms of Lyme disease after you’ve completed your treatment?

DEAR DOCTOR K: My neighbor was diagnosed with Lyme disease. Why does he still have symptoms, even though he has completed his treatment?

DEAR READER: The great majority of people diagnosed with Lyme disease, and properly treated, are cured. However, there are some people like your neighbor, who are never fully cured, and we do not understand why proper diagnosis and treatment does not always lead to the elimination of suffering. Here's what we do know. Lyme disease is an infection caused by bacteria that are transmitted through tick bites.

What is mononucleosis– why is it called the “kissing disease”?

DEAR DOCTOR K: What is mononucleosis, and why is it called the "kissing disease"?

DEAR READER: Mononucleosis, or "mono," is an illness caused by several viruses, primarily the Epstein-Barr virus (EBV). Mono was nicknamed the "kissing disease" because EBV commonly is transmitted during kissing. The virus lives in different parts of the body, including the throat. The virus can leave throat cells and enter the saliva. Most viruses that infect us enter our body, maybe cause temporary illness, and then get killed by the immune system.

What is a virus — what makes viral illnesses so difficult to treat?

DEAR DOCTOR K: What is a virus? And what makes viral illnesses so difficult to treat?

DEAR READER: Viruses are a very simple kind of germ. They are smaller and simpler than other common germs, such as bacteria and fungi. They cause illnesses ranging from mild -- like the common cold -- to potentially fatal. This includes diseases such as smallpox, influenza, Ebola and HIV.

What is the best way to remove a tick from your skin?

DEAR DOCTOR K: I live in a heavily wooded area, so I'd like to know the best way to remove a tick if you spot one on your skin.

DEAR READER: Knowing how to remove a tick is a useful skill for anyone who spends time outdoors, or who cares for someone who does. The sooner a tick is removed -- correctly -- the less likely the critter can deliver bacteria that cause Lyme disease or other tick-borne diseases.

Should I be worried about the new kind of “bird flu” discovered in China?

DEAR DOCTOR K: I heard that a dangerous new kind of "bird flu" was recently discovered in China. Should we in the United States be worried?

DEAR READER: You're right: In March 2013, cases of a brand-new kind of bird flu were discovered in China. One of the hardest things to predict is what will happen when a new strain of the influenza ("flu") virus first infects humans. I'm not exaggerating when I say it could turn out to pose no threat at all in the U.S., or it could be truly terrible.

What is C. diff infection?

DEAR DOCTOR K: I've heard that an illness known as "C. diff" is running rampant in hospitals. What is it? How can I avoid it during my upcoming hospitalization?

DEAR READER: You're referring to a dangerous intestinal infection caused by a bacterium known as Clostridium difficile, or "C. diff." C. diff bacteria, and the spores they produce, are not just in hospitals; they're everywhere. And they're not just in the environment around us; they're also inside many of us, in our intestines, along with trillions of other bacteria.

What is infectious arthritis?

DEAR DOCTOR K: I saw my doctor for pain and inflammation in my knee. He said I have arthritis caused by a bacterial infection. Could this be true?

DEAR READER: I'll bet that, like many of my patients, you think of arthritis as something caused by wear and tear on a joint. That is the main cause of the most common type of arthritis, osteoarthritis. However, there are other kinds of arthritis, too.

Can pelvic inflammatory disease affect fertility?

DEAR DOCTOR K: I have pelvic inflammatory disease, and I'm worried this could affect my fertility.

DEAR READER: You're right to be concerned. Pelvic inflammatory disease (PID) is the most common preventable cause of infertility in the United States. The more often a woman gets PID, the greater her risk of becoming infertile. Most cases of PID develop from sexually transmitted diseases (STDs), usually gonorrhea or chlamydia.

Do vitamin C or milk have an effect on colds?

DEAR DOCTOR K: My mom always told me to take vitamin C and not to drink milk when I had a cold. Is this true or just an old wives' tale?

DEAR READER: The idea that vitamin C supplements might prevent the common cold, or shorten the duration and reduce its symptoms, was popularized by the biochemist Linus Pauling. Randomized controlled trials involving thousands of people were conducted. My interpretation of the results of those studies is that they showed no evidence that vitamin C supplements reduced the duration or severity of the common cold. There was weak evidence that they might reduce the risk of catching it.

How can I prevent food poisoning?

DEAR DOCTOR K: I recently suffered through a miserable bout of food poisoning. How can I protect myself in the future?

DEAR READER: There are few things less fun than food poisoning. I speak from experience, and not just experience as a doctor. Abdominal cramping, vomiting and diarrhea -- clearly not an experience you want to repeat. Fortunately, there are many things you can do to protect yourself.