Dear Doctor: I've been reading a lot of warnings about the recent wet weather causing an abundance of ticks and their potential to cause disease. I knew about Lyme disease, but now Powassan virus? What's that? And just how dangerous are ticks?

Dear Reader: Ticks are external parasites that, because they feed on blood, are quite efficient at transmitting disease. In each of the three life stages that a tick goes through after hatching, it needs blood to survive. Depending on the species, ticks will feed on mammals (that's us), birds, reptiles and amphibians.

A variety of ticks throughout the United States can transmit more than a dozen dangerous and sometimes deadly diseases. These include Lyme disease, Rocky Mountain spotted fever, tularemia, and Colorado tick fever, to name a few of the most commonly known. The tick picks up the disease while feeding on an infected host, and then can transmit it through its saliva during future feedings.

One of the lesser-known diseases is Powassan virus, a flulike illness that can cause inflammation in the brain. It is spread by several types of ticks found in the northeastern states and in the Great Lakes region. The disease is fatal in up to 15 percent of individuals who show symptoms. About half of those who survive face ongoing neurological difficulties.

Powassan virus was once rare, with about two reported cases per year between 1950 and the early 2000s. That number has risen to 75 reported cases in the last decade, or close to eight per year. Some experts believe this may be due to increased awareness in diagnosing the disease.

However, Lyme disease, with close to 30,000 confirmed cases each year, remains the most common tick-borne illness in the U.S. According to the Centers for Disease Control and Prevention, the total may actually be as high as 300,000 infected individuals per year, when unconfirmed cases are factored in.

While there are some species of ticks that don't carry disease, without specialized knowledge it's almost impossible to tell them apart from those that do. As a result, the best advice is to protect yourself, your family and your pets against all tick bites.

Ticks prefer areas that are moist and humid, and concentrate in wooded and grassy areas. They can't jump or fly, so they perch at the tips of grasses and shrubs, where they can easily attach to a host as it brushes by.

To avoid tick bites:

-- When in grassy or brushy areas, wear long sleeves, long pants and close-toed shoes. Tuck pants into socks. Light-colored clothing makes spotting ticks easier.

-- Insect repellents that contain 20 percent DEET may be helpful. Some experts say picaridin is even better. Reapply according to manufacturer instructions.

-- Treat clothing, boots and tents with products containing 0.5 percent permethrin, which stays effective through several washings. Pre-treated clothing and gear is also available and may offer longer protection.

-- After spending time outdoors, be sure to do a tick check. Visually scan all areas of your body, including your scalp and hair.

(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 know that as far as medical problems go, eye "floaters" are pretty minor. But I've just noticed some new ones, and they're really annoying. What are they? Is there any way to get rid of them?

Dear Reader: Floaters are those tiny specks, strands or cobwebs that drift across your field of vision. Try to look right at them and they'll skitter away. Move your eyes away from them and they'll follow. Hold your gaze still and they'll gently float about, which is the trait that gives them their name.

Floaters develop in the vitreous -- the clear, gel-like fluid that fills the space between the lens at the front of the eye and the retina at the rear. It's composed mostly of water, with a small amount of collagen, other proteins, salts and sugars. The job of the vitreous is to protect the delicate structures of the eye, support the eyeball's spherical shape and hold the light-sensitive cells of the retina in place.

Although people of any age can develop floaters, they do tend to be more common in adults 40 and over. That's because as we age, the vitreous gradually softens and shrinks. Portions of the collagen can become stringy, and the other proteins dissolved in the vitreous form tiny clumps. As these bits and strands float in the jelly-like vitreous, they cast shadows on the retina. The retina then sends this information to the brain via the optical nerve. The result is a visual image of the changes taking place within our eyes.

For the most part, the presence of floaters is a normal part of aging. However, if the number of floaters suddenly increases, and if the increase is accompanied by flashes of light within the field of vision, it's time to check in with your eye doctor. These can be the signs of more serious problems.

We understand your frustration with floaters -- no matter where you look, there they are. However, at this time, there are no good solutions for dealing with them. For those (extremely) rare individuals for whom floaters are so numerous that they interfere with vision, treatment options do exist.

One choice, which is rarely used, is laser therapy. In this approach, an ophthalmologist targets the floaters with a special laser. The idea is that the energy of the radiation will break up the floaters so they become less visible. The risk is that the laser can cause damage to the retina.

The other option is a surgical procedure known as a vitrectomy. The vitreous -- along with all the floaters -- is removed via an incision, and is replaced with a saline solution. This also carries serious risk. Complications include retinal detachment, retinal tears and cataracts.

Do-it-yourself approaches to dealing with floaters, which, unfortunately, don't have much effect, range from harmless (eye exercises, eating more blueberries or broccoli) to potentially dangerous. Your eyesight is far too precious to risk, so don't try anything without checking with your doctor first.

Given time, your brain will tag floaters as unimportant information and, for the most part, will let you forget them.

(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 44 years old and have never had hay fever in my life. This spring, just as everything was turning green and the flowers were blooming, my eyes started to itch, my nose was running, and I was sneezing all the time. I know I didn't have a cold. Is it possible that I've developed an allergy?

Dear Reader: We regret being the bearers of bad news, but yes, adult-onset allergies are definitely a phenomenon. From your description of your symptoms and their timing, they do sound consistent with allergic rhinitis, also known as hay fever.

An allergy occurs when an otherwise harmless substance gets flagged as dangerous by the immune system, which then launches an attack. Common allergens include pet dander, pollen, grass, mold spores, dust mites and certain proteins found in foods. The symptoms you described -- itchy eyes, runny nose and sneezing -- are the result of your immune system ramping up to evict the perceived intruders.

Although adult-onset allergies are not a widespread phenomenon, reports from allergists and immunologists make it clear that they are on the rise. Researchers have several theories about how and why this is happening, but a definitive answer is not yet known.

One theory that has gained traction is the "hygiene hypothesis." The idea is that in our modern world, we spend most of our time in spaces that are sealed off from the outdoors. As a result, we have very little contact with the array of plants, soils, pollens and animals in the natural world.

This results in an immune system with so little to do that it has become hypervigilant. Instead of giving harmless substances a pass, the immune response goes a little crazy and launches an all-out attack. It's not that the immune system has become ineffective, but rather it has developed reactions that are inappropriate and are out of proportion to the perceived threats.

A different school of thought brings the body's microbiome into play. That's the collection of trillions of bacteria and viruses that live within the gut and upon our skin. As we are now learning, these play a surprisingly crucial role in the functioning of many systems of the human body.

This theory of how and why allergies develop views our bodies as a balanced ecosystem. The idea is that when factors like illness, pollution, poor diet or the overuse of antibiotics affect the makeup and diversity of our microbiomes, we become more susceptible to developing allergies.

A definitive answer may one day point to new ways to manage or even "cure" allergies. But until then, we'll rely on what we already know.

First, we recommend that you see your primary care physician for a definitive diagnosis. Hay fever symptoms can be managed with antihistamines or decongestants, which your physician may recommend. And limiting exposure -- staying indoors during peak pollen season, using air conditioning instead of fans, investing in an air purifier and wearing sunglasses can help make this new (again, we're so sorry) allergy more bearable.

(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.)