Infectious Diseases

I’m a healthy 55-year-old man. Should I get the shingles vaccine?

DEAR DOCTOR K: I'm a healthy 55-year-old man. Should I get the shingles vaccine? And while you're at it, what exactly is shingles?

DEAR READER: Shingles is a condition that results in a rash and pain. It is caused by the same virus (called VZV) that causes chickenpox. After a case of chickenpox, the virus can lie dormant inside your nerves for decades. By "dormant," I mean that it is not multiplying -- it just lies there inside the nerve cells.

How are the West Nile virus and Eastern equine encephalitis illnesses spread?

DEAR DOCTOR K: I've been hearing about West Nile virus and Eastern equine encephalitis. How do these illnesses spread? What can I do to protect myself?

DEAR READER: West Nile and Eastern equine encephalitis (EEE) are both viral diseases spread by mosquitoes. Infections with these viruses can be dangerous. In some infectious diseases, as with these, the disease-causing microbe lives in an insect. When that insect bites a person, the microbe is transferred from the insect to the person. Often these microbes don't cause any illness in the insect -- just in us. West Nile virus was first detected in the United States in 1999.

Why am I being tested for tuberculosis? I thought that was eradicated.

DEAR DOCTOR K: Why does my doctor want to test me for tuberculosis? I thought that was eradicated a long time ago.

DEAR READER: It would be wonderful if tuberculosis (TB) had been eradicated long ago. Unfortunately, that's not the case. The annual number of new cases in the United States has been dropping over the past 20 years. However, around the world, particularly in developing nations, TB remains a huge problem. More than 1 million people die of TB each year. TB is an infectious disease, caused by a particular kind of bacteria.

How can I protect myself and my family against Lyme disease?

DEAR DOCTOR K: A young pop singer who battled Lyme disease was recently on the cover of People magazine. I know it's silly, but if a celebrity can get a disease, I feel I'm more vulnerable. What should I do to protect myself and my family?

DEAR READER: Lyme disease is a serious illness that can have lasting effects. Fortunately, there are many things you can do to protect yourself. Lyme disease is an infection caused by bacteria that live inside insects (primarily deer ticks). When the ticks bite us, the bacteria enter our bodies. Deer ticks are very small, about the size of a poppy seed.

What is malaria and how can I prevent it?

DEAR DOCTOR K: I am traveling abroad in a few weeks. My travel clinic has prescribed antimalarial medication. Can you tell me more about malaria and how to prevent it?

DEAR READER: Malaria is a serious disease caused by the Plasmodium parasite. The parasite is not found today in the United States or Canada, but it is common in areas to which North Americans travel: Africa, Asia, and Central and South America. The U.S. Centers for Disease Control and Prevention estimate that there are over 200 million new cases of malaria each year around the world.

What is fifth disease and is it contagious?

DEAR DOCTOR K: A child in my son's class has "fifth disease." What is this? Is it contagious? What can I do to prevent my son from catching it?

DEAR READER: Fifth disease, also known as erythema infectiosum, is a common viral infection among school-aged children. It is caused by a virus called parvovirus B19. Fifth disease usually is a mild illness. Some people who are infected with the virus may never realize they have it. When symptoms do occur, they may include a stuffy nose, runny nose, slight fever, or body aches, headache, nausea, diarrhea and fatigue. These symptoms pass after three or four days.

What is MRSA and why is it so dangerous?

DEAR DOCTOR K: What is MRSA? What makes it so dangerous?

DEAR READER: We have a brain, and bacteria don't. So you'd think bacteria wouldn't be able to outsmart us. But they sure can figure out ways to become resistant to the antibiotics we use to kill them. In the early days of antibiotics, 70 years ago, one of the most common and dangerous types of bacteria -- Staphylococcus aureus -- could be killed by penicillin.

Is there a treatment or vaccine being created for Ebola?

DEAR DOCTOR K: Like everyone, I'm afraid that the Ebola virus could spread in the United States. There must be research underway to find treatments, and vaccines to prevent it in the first place. Please tell me there is.

DEAR READER: Infection with the Ebola virus is indeed frightening. In West Africa, the site of the latest outbreak of Ebola, more than half the people who have become infected with it have died. I doubt there will be an epidemic of Ebola in the U.S. and other developed nations, but there have been cases, and there will be more.

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.