Diseases & Conditions Archive

Research we're watching

You may be more likely to get COVID-19 from someone without symptoms than from someone who is feverish and coughing, according to a study published online Jan. 7, 2021, by JAMA Network Open. Study authors calculated that more than half of all COVID-19 cases were likely spread by someone without symptoms of the disease. Drawing on data from eight Chinese COVID-19 studies, the researchers developed a model that could estimate how people were infected, specifically looking at whether an infection would likely have come from someone with or without symptoms. They broke the asymptomatic people into two groups: those who were infected but hadn't yet developed symptoms (presymptomatic), and those who were infected but never got symptoms. Study authors assumed that it took five days from exposure for symptoms to develop or for someone to receive a positive test. The model also assumed that people were infectious for 10 days. Using these assumptions, they determined that 59% of people were infected by someone without symptoms. Thirty-five percent of the total would have been infected by someone who was presymptomatic, and 24% by someone who would never develop symptoms. These numbers rose when the researchers modified their model to assume that everyone was infectious a day earlier. Under this second model, 67% of cases were spread by someone without symptoms.

The researchers said their findings show the importance of public safety measures such as mask use, avoiding gatherings, distancing, and handwashing, all of which can reduce the spread of COVID-19 by people who don't know they have it.

A ringing sound in one or both ears is usually a form of an annoying condition called tinnitus. When tinnitus persists, treatment  such as cognitive behavioral therapy, tinnitus retraining therapy or biofeedback, can ease symptoms.

This often scary condition can happen at almost any time.

Everyone experiences an occasional bout of feeling dizzy. But vertigo is a distinct type of dizziness, with an estimated 40% of adults suffering from it at least once in their lifetime — and the risk rises with age.

"Because vertigo often strikes out of the blue, an acute attack can be potentially dangerous by increasing your risk of a fall," says Dr. Howard LeWine, chief medical editor of Harvard Health Publishing. "While there is no cure for most causes of vertigo, there are ways to reduce symptoms during an attack and avoid recurrent episodes."

In the journals

Bleeding gums are a sign of gingivitis, an early stage of periodontal disease, but they may also signal low vitamin C in your diet, suggests a study published online Feb. 1, 2021, by Nutrition Reviews. Researchers examined 15 published studies involving 1,140 healthy people as well as data on 8,210 people from the CDC's Health and Nutrition Examination Survey. They found that low vitamin C levels in the bloodstream were associated with an increased risk for gum bleeding with gentle probing. The researchers also observed that increasing vitamin C intake may help resolve the problem.

Increased bleeding in general is one of the symptoms of scurvy, a disease caused by severe vitamin C deficiency. Scurvy, which often affected 18th-century sailors without access to fruits and vegetables, is rare today. Still, this new study sheds light on a potential cause of gum bleeding related to vitamin C levels that are only slightly low — not enough to cause scurvy.

You have the power to reduce certain risk factors for the disease.

We've come a long way in our understanding and treatment of age-related macular degeneration (AMD), the leading cause of vision loss for people ages 50 or older in the United States. We've learned that certain genes and lifestyle factors increase the risk for developing AMD, and discovered treatments that often slow the disease's progression.

Yet for all our advances, we still don't have a guaranteed way to prevent AMD. You are at greater risk if one of your parents had the condition. "One needs to be concerned, but it doesn't mean you're destined to get it. It's a complex disease, and it takes a combination of factors for it to develop," says Dr. Joan W. Miller, chief of ophthalmology at Harvard-affiliated ­Massachusetts Eye and Ear and ophthal­mology chair at Harvard Medical School.

A history of discrimination in multiple settings, including health care, may make some people who identify as LGBTQ+ hesitant to get a COVID-19 vaccine, even though the virus has disproportionately harmed this community. If you're struggling to make a decision, this may help you consider benefits and risks.

Obstructive sleep apnea leaves people tired, but also puts them at risk for other health problems. Not everyone with sleep apnea can use an airway pressure machine, and some may simply prefer not to. There are oral appliances available, but are they effective?

Men may avoid activity because of their knee pain, but movement is exactly what they need.

It is perhaps the ultimate exercise catch-22: it's hard to move with knee osteoarthritis, but moving helps relieve osteoarthritis knee pain.

More than 30 million Americans have osteoarthritis, the most common kind of arthritis. While osteoarthritis can affect the hips, lower back, neck, and fingers, it occurs most often in the knees. In fact, an estimated 10% of men ages 60 and older have symptoms of knee osteoarthritis.

On call

Q. My breasts have begun to feel swollen and seem larger. What could cause this, and should I be worried about any potential health issues?

A. Swollen breasts in men are almost always caused by either one or both of two conditions: excess fat deposition in the breasts, or growth of actual glandular breast tissue (gynecomastia). Fatty deposition occurs in overweight men and is always present in both breasts. With gynecomastia, the breasts have a firm or rubbery consistency. While it usually affects both breasts, it can affect one breast much more than the other.

Try stress reduction to improve your quality of life and potentially relieve allergy symptoms.

Spring allergies are a stressful business. Coping with watery eyes, a runny nose, sneezing, coughing, or a sore throat affects how you get through each day. "The primary consequence is a reduced quality of life. This naturally can lead to stress on patients and their families," says Dr. Ahmad Sedaghat, an ear, nose, and throat specialist at Harvard-affiliated Massachusetts Eye and Ear Infirmary.

The influence goes both ways: not only can allergies cause stress, but stress can make allergies worse.