Diseases & Conditions Archive

Research we're watching

Rabies infections are extremely rare in the United States, with only approximately one to three cases seen each year. That number has dropped significantly since the 1930s and 40s when there were 30 to 50 cases during the average year. But when they do occur, they're typically transmitted by infected bats. According to a new report by the CDC, the majority of people who have died from rabies in the United States were infected through contact with a bat. This is the case even though bats represent only one-third of the 5,000 rabid animals typically seen in the United States each year. The second most common source for rabies infections in Americans is rabid dogs encountered when people are traveling overseas.

To prevent exposure to rabies, be certain to let your doctor know if you are scratched or bitten by a bat, or if you awaken with one flying around your house or bedroom, says the CDC. If you are exposed to rabies, your doctor can administer a series of shots (known as post-exposure prophylaxis) before you develop symptoms, which can prevent you from developing a rabies infection, which is almost always fatal. If you are traveling outside the United States, be aware that dogs may carry the infection.

Ask the doctors

Q. I understand that shingles is caused by a virus. Does that mean that shingles is contagious?

A. Yes and no. If you had chickenpox when you were a child, you are at risk for shingles. Shingles occurs when the varicella-zoster virus that caused your chickenpox re-emerges after lying dormant in your nerve cells from the time of your original illness. When this occurs, you are contagious, but you can't give someone shingles. You can, however, infect people with chickenpox if they haven't been exposed to the virus in the past and haven't been vaccinated against it. For this reason, it's important to take precautions, particularly if you are close to someone who has a weakened immune system.

Hemorrhoids are common and can be extremely painful and uncomfortable during occasional flare-ups. These swollen blood vessels on the outer rectum and anus can bleed and turn bowel movements into intensely painful experiences. But simple hemorrhoid self-help measures can ease the ordeal of most hemorrhoids and allow healing. Dr. Jacqueline Wolf, a gastroenterologist and associate professor of medicine at Harvard-affiliated Beth Israel Deaconess Medical Center, suggests some effective steps you can take to care for hemorrhoids—and when it's time to seek out a procedure to remove them.

Step up the fiber

Hemorrhoids come in two varieties. The internal type sprout from within the rectum. External hemorrhoids develop on the anus itself. Either way, passing stools by hemorrhoids may cause pain and bleeding.

Ask the doctors

Q. My mother has fibromyalgia, and I think I'm starting to experience similar symptoms. Is fibromyalgia hereditary?

A. Yes. Fibromyalgia, a chronic pain condition that affects some six million or more Americans, can run in families. In fact, one of the most important risk factors for fibromyalgia is a family history of the disorder. Fibromyalgia is sometimes known to affect multiple members of the same family. Your risk rises if you have a first-degree relative — a parent, a brother, sister, or child — with the condition.

In the journals

Previous studies have shown a link between loss of smell among older adults and risk of death within a short period — often five years or less. Now, a report published online May 21, 2019, by Annals of Internal Medicine confirmed this increased risk of death over more than a decade, as well as identifying the leading causes of death.

Researchers gave smell identification tests to 2,289 adults ages 71 to 82 (about half of whom were men). They found that those who scored low on the smell test had a 46% higher risk of dying within 10 years, and 30% within 13 years, compared with those who had a stronger sense of smell.

These two common conditions have many overlapping risk factors, but they both respond to healthy lifestyle changes.

The biggest organ inside your body, your liver, lies just below and to the right of your heart. This powerhouse organ performs many vital roles in the body, including processing cholesterol and making proteins that help your blood clot. But as many as one in four Americans has a potentially dangerous accumulation of fat inside the liver. This condition, known as non-alcoholic fatty liver (NAFL), often goes hand in hand with obesity and diabetes. Both of those conditions boost the risk of heart disease, and growing evidence also links NAFL with cardiovascular problems.

"The connection between fatty liver and early signs of plaque in the coronary arteries is increasingly compelling," says Dr. Tracey Simon, a hepatologist at Harvard-affiliated Massachusetts General Hospital (MGH). Excess fat around the liver and other organs in the abdomen—known as abdominal obesity — is another likely related problem. In fact, abdominal obesity seems to accelerate the progression of fatty liver to a more serious form of the problem, nonalcoholic steatohepatitis, or NASH (see "The many faces of fatty liver disease").

On call

Q. Is there any difference between sunstroke and heatstroke and are there certain signs and symptoms I should look for?

A. These two terms refer to the same condition. Heatstroke (or sunstroke) happens when the body can no longer maintain a temperature of under 105° F when exposed to hot weather. People almost always have warning symptoms before heatstroke, yet sometimes they do not pay attention, or are not able to take action.

How a healthy lifestyle can make a difference in Alzheimer’s prevention.

Alzheimer's disease, the most common form of dementia, is characterized by the accumulation of two types of protein in the brain: tangles (tau) and plaques (amyloid-beta). Eventually, Alzheimer's kills brain cells and takes people's lives.

Alzheimer’s causes

What causes Alzheimer's? We still aren't sure. "For 1% of all cases, there are three genes that determine definitively whether or not you will have Alzheimer's, and all three relate to amyloid-beta production, which in these cases is likely the cause of Alzheimer's," says Dr. Gad Marshall, associate medical director of clinical trials at the Center for Alzheimer Research and Treatment at Harvard-affiliated Brigham and Women's Hospital. "For the other 99%, amyloid and tau are closely associated with Alzheimer's, but many things may contribute to the development of symptoms, such as inflammation in the brain, vascular risk factors, and lifestyle."

Ask the doctor

Q. I hear that there are outbreaks of measles in the United States. I think I had measles when I was young, but I'm not sure. Do I need to worry?

A. The measles virus has been infecting humans for at least 1,000 years. When I was very young, in the 1940s, I got the measles. So did nearly every kid I knew; it is very contagious. I had a high fever, sneezing, coughing, very red eyes, and then a rash on my face and all over my body. Fortunately, I didn't develop the severe complications of measles: pneumonia (which affects one in 20 people with measles) or encephalitis (which affects one in 1,000 and can be fatal). Still, I was miserable for more than a week.