Dear Doctor: Please tell me more about the recent story in the news about the young woman who spent time on a ranch and then found worms living inside her eyes. We are cattle ranchers, and now I'm worried about my husband and kids.

Dear Reader: You're correct -- a 26-year-old woman from Oregon discovered that she was infected with Thelazia gulosa, a parasite commonly known as the cattle eye worm. Dogs and other canids, cattle and horses are the most common hosts. We hope that you'll be reassured to learn that this is the first reported case of infestation of the cattle eye worm in a human host.

For those of you who missed the (fairly robust) media coverage of the story, here's the gist. In 2016, a young woman who was working on a commercial fishing boat in Alaska thought she felt an eyelash in her eye. Although she rubbed her eye and flushed it with water, the scratchy, itchy sensation persisted. After a moment of looking in a mirror, she finally saw something above the lower lid of her left eye and lifted it out. Instead of one of her own brown lashes, she was looking at a slender white thread about a half-inch long -- a living worm.

She went to an urgent care clinic and an ophthalmologist before seeing an infectious disease specialist. A team of parasitologists at the Centers for Disease Control and Prevention eventually nailed the diagnosis. In all, a total of 14 worms were removed from the young woman's eye. It was by reading a research paper written in Germany in 1928 that a scientist from the CDC's Parasitology Reference Diagnostic Laboratory finally identified the cattle eye worm.

So how did this happen?

Infestations of Thelazia, a genus of nematode worms that live as parasites in the eye and its surrounding tissue, are most commonly seen in animals and birds. Their spread to humans is extremely rare. In fact, just 10 other cases of eye worm infestation have ever been reported in North America. The most recent case in the United States was reported more than two decades ago. None of those 10 cases involved the cattle eye worm.

Although it's impossible to know for sure, the thinking is that the young woman may have picked up the parasite while spending time at an inactive cattle ranch. The worms are carried by the flies that you see buzzing around the faces of cattle and horses. The worm larvae, which reach maturity inside the digestive tracts of the flies, move to their next host when the fly lands on the cow's eyeball to drink. There, the eye worm grows to adulthood and produces more larvae, which are then picked up by new flies.

The good news is that because eye worms need the flies to reach maturity, their life cycle ends in a human host. With those 14 worms removed from her eyes, the young woman's infestation was over. No permanent damage was done.

As for the rest of us, even if we spend time near cattle or horses, the chances of picking up the parasite are extremely small. Be sure to keep flies away from your face and eyes, and if one lands, remove it promptly.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: I'm 88 and have small, brown, rough -- and very itchy -- spots that develop on my back and other areas. If I can scratch them off, the itching goes away. One spot that I didn't scratch off is now embedded and I can't get it off. Two dermatologists have basically said, "It's your age. Live with it." Isn't there another answer?

Dear Reader: You seem to be describing seborrheic keratoses (the singular is keratosis). These scaly, thickened growths appear to be "stuck" on the skin, sort of like wall putty. Like wall putty, these lesions can often be scraped off; unlike putty, however, they can come back on their own. Although most lesions are brown, they can also be white, black, yellow or grayish. They normally appear after the age of 50 (so, yes, they are common at your age), but can begin in one's 30s.

Seborrheic keratoses can occur anywhere upon the body except the palms and soles, and the lesions are more likely to occur in sun-exposed areas of the body. Some people have a few lesions; others may have hundreds. Such keratoses can be irritated by clothing -- especially bras -- leading to itching, pain and bleeding.

Although the sun may be a factor in the development of such lesions, their origin largely remains a mystery. We do know that when normal cell death is disrupted, skin cells accumulate, bunching up on top of each other. It's possible this disruption is caused by a genetic mutation in the skin cells; in fact, the likelihood of such lesions does seem to be influenced by genetics.

Because the lesions resemble warts, many medical experts have postulated that the human papilloma virus (HPV), which creates warts, is the cause. A 2004 study took biopsies of seborrheic keratoses from 55 people and compared them with 48 biopsies of normal skin in other individuals. Although the researchers found HPV in 76 percent of the keratoses, they couldn't conclude that HPV was the cause.

Doctors are usually not worried about seborrheic keratoses (as your experience attests), because the likelihood of them becoming cancerous is extremely small. But although the lesions are not harmful, they're not pretty either, which is the primary complaint against them. The basic treatment is to try to destroy them, especially if they're causing irritation. Biopsies are rarely necessary unless something about the lesion looks cancerous.

Liquid nitrogen is often the first choice of doctors trying to destroy seborrheic keratoses. It makes the lesions blister and then fall off -- which may be a good option if it is overly itchy or painful -- but the lesions can return. Doctors can also shave off the lesions, but this can lead to bleeding and scarring. Laser therapy can remove the lesions as well, but is rarely used.

As for topical treatments, the retinoid cream tazarotene can diminish seborrheic keratoses, as can a topical medication used for warts, imiquimod.

In the future, when science has figured out the cause for seborrheic keratoses, doctors will be more apt to prevent these lesions from occurring, perhaps through a vaccine. In the meantime, if these lesions are not physically irritating, there is no pressing need for treatment. So, you may just have to live with it.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: I'm 84 and live in a big city. I try to walk as many places as I can, but I've read that air pollution may shorten the lifespan of seniors. Should I stay inside instead?

Dear Reader: As we enter our later years, we become increasingly vulnerable to health issues like chronic illness and infection, and to the negative effects of environmental factors like air pollution. At the same time, our immune systems are changing. As they become less robust, we lose the ability to respond to and recover from adverse conditions.

You are correct that studies have found a direct correlation between the degree of outdoor air pollution in a particular location and the lifespans of the individuals who live there. While air pollution affects people of all ages -- it's connected to at least 3.7 million premature deaths per year worldwide -- it's particularly hard on the elderly and the very young. In older individuals, it has been shown to exacerbate the effects of chronic disease and respiratory tract infections.

Outdoor air pollution is generated by emissions from traffic, factories and other industries, power generation, wood-burning fireplaces, wildfires, wind-blown dust and particulates, which are minute solid particles and liquid droplets suspended in the air. Ongoing exposure to outdoor air pollution has been tied to the increased incidence of conditions like asthma, chronic obstructive pulmonary disease (COPD), chronic bronchitis and emphysema. Researchers now have evidence that long-term exposure to outdoor air pollution can have an adverse effect on both heart and lung function in otherwise healthy individuals.

That's quite a bit of somewhat dire information, so we're happy to follow it up with steps you can take to reduce the risks of both indoor and outdoor air pollution, no matter where you live.

Let's start with your concerns about walking outdoors. We believe that the physical and mental health benefits of physical activity are significant enough that you should make every effort to stick to your fitness routine. If you have internet access, you can check on the air quality in your city each day at airnow.gov. This information is also provided in many television and radio weathercasts. When conditions are right and you do go walking, steer clear of the busier streets and avenues. Find quiet streets with minimal traffic for your walks. And remember to always wear sunscreen. Using an umbrella or parasol for shade and added coolness can also be a good idea.

When air quality is less than optimal, your instincts are correct -- you should limit your time outdoors. And though we've focused on air quality, it's important to be aware of the dangers that heat poses to elderly individuals. On days with high temperatures, take your walk in the early morning. When it's already too warm in the morning, stay inside near a fan or an air conditioner. And if your home is too warm, please take advantage of your local senior citizen center, or the cooling stations that most cities make available to residents during heat waves.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)