Infectious Diseases

Does the immune system really change with the seasons

DEAR DOCTOR K: A friend heard about a study that said a person's immune system changes with the seasons. That seems incredible to me. But if it's true, it's fascinating. Do you know what she is talking about?

DEAR READER: I think I know the study she is referring to. Before describing what it found, it's worth talking a bit about the immune system and also about genes.

What is sepsis?

DEAR DOCTOR K: My father had routine surgery. Soon after, he developed something called sepsis that almost killed him. He's OK now, but I'd like to understand what happened to him.

DEAR READER: He and you are lucky. Not everyone makes it. Sepsis is a condition in which the immune system goes awry. Think of the immune system as our personal army, with an arsenal of weapons. It is meant to protect us from foreign invaders (like germs). Unfortunately, in attacking foreign germs, it sometimes can go overboard -- and its weapons can injure us.

Will a pertussis booster shot for me help protect my grandkids from whooping cough?

DEAR DOCTOR K: My son says that if I get a booster shot for pertussis, it will help protect his kids from getting whooping cough. That seems far-fetched to me.

DEAR READER: It's not far-fetched. Even if you were immunized against pertussis (the bacteria that cause whooping cough) as a child, you may need a booster shot. Why? Because pertussis is highly contagious, and without a booster shot you are at some risk for getting it. And if you get it, you could pass it on to your grandkids.

Should I get a flu vaccine this year even if last year’s vaccine didn’t prevent me from getting the flu?

DEAR DOCTOR K: I got the flu vaccine last year and still got the flu. Should I even bother with the flu vaccine this late?

DEAR READER: Yes, you should, but don't expect perfect protection this year, any more than you should have last year. Vaccines contain fragments of three or four strains that are predicted to dominate during the coming flu season. Different strains of the virus circulate each flu season (October-May).

How can I prevent recurrent UTIs?

DEAR DOCTOR K: I'm in my 30s and fairly healthy. However, I keep getting urinary tract infections. My husband and I want to know what I can do to prevent them.

DEAR READER: Many women know well the symptoms of a urinary tract infection (UTI). You might feel a frequent urge to urinate, yet pass little urine when you go. It may hurt when you urinate. Your urine might be cloudy, blood-tinged and strong-smelling. Furthermore, many women have a tendency to get repeated UTIs. UTIs are usually caused by bacteria that live in the gut and are present on the skin around the rectum.

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.