Dear Doctor: What's the deal with the tick bite that makes you allergic to meat? Will I know if it happens to me?

Dear Reader: Sounds like science fiction, right? A single tick bite scrambles your immune system so that overnight you become allergic to foods you've been eating your entire life. But unfortunately for a small but growing number of people in the United States, this scenario is all too real.

The culprit is the Lone Star tick, which is widely distributed throughout the Eastern, Midwestern and Southeastern states. Recent studies suggest that the tick may be on the move. It has been identified as far north as New York state and Maine, and as far west as Texas. It gets its name from the single splotch, or "star," that the adult female has on her back.

It was in 2009 that scientists first began to connect the dots between the Lone Star tick and a rather unusual immune response. Certain people who were bitten by the tick went on to develop a sudden and sometimes quite serious allergy to red meat. This includes beef, lamb and pork.

Something in the tick bite sends alarm bells ringing in the immune system, ordering it to target a specific carbohydrate found in meat. The full name is galactose-alpha-1,3-galactose, but it's commonly shortened to alpha-gal.

The specific agent that causes the allergy, be it a microbe or a biological compound found in the tick's saliva, is under study. So far scientists have been left with far more questions than answers. This includes whether the sensitivity to alpha-gal can be reversed.

In most food allergies, the physical response is swift. Eat a strawberry and a few minutes later, you break out in hives. With the alpha-gal allergy, however, it can take the body up to 12 hours to react. The slow onset of alpha-gal allergy symptoms can make the diagnosis a challenge.

The most common symptoms are stomach pain, nausea, hives, skin rash, sneezing, headaches and wheezing. In severe cases, anaphylactic shock is possible. The allergic reaction can happen after just a single bite of meat. It has also been observed in people taking medications that contain gelatin, as well as those using new cancer drugs derived from genetically modified mice.

The recent spread of the alpha-gal allergy beyond the traditional borders of the Lone Star tick's range has scientists questioning whether other species of ticks may also be involved. If you've recently been bitten by any tick and suspect you may have developed an alpha-gal allergy:

-- Stop eating red meat or any other foods that trigger symptoms.

-- Know that some symptoms can be controlled with antihistamines and corticosteroids.

-- For severe reactions, including anaphylaxis, use injected epinephrine, which requires a prescription.

For an accurate diagnosis, make an appointment with an allergist. He or she will want to know:

-- What you ate that triggered the symptoms.

-- The time frame in which symptoms appeared.

-- The specifics of the symptoms and how long they lasted.

A blood or skin test will show whether food-specific antibodies are present. Your allergist will use the results of these tests to arrive at a diagnosis.

(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: Is there any treatment besides surgery that can reliably help an older man urinate when he is experiencing difficulty due to prostate enlargement?

Dear Reader: This common problem becomes all the more common as men get older. In fact, 40 to 50 percent of men ages 51 to 60 -- and up to 80 percent of those over 80 -- have prostate enlargement. Slightly more than half suffer symptoms, which include poor urine flow, frequent urination, incomplete emptying of the bladder and, most irritatingly, waking up multiple times at night to urinate. Some of these symptoms can be improved by decreasing alcohol and caffeine and by decreasing evening fluid intake.

Drug treatment is the first line of therapy. Alpha-1 receptor blockers work to relax the smooth muscles in the prostate and the lower portion of the bladder. This relaxation allows the urine to flow more easily from the bladder. The biggest side effect is lightheadedness, because the drug also lowers blood pressure. This lightheadedness has not been reported as much with newer formulations -- tamsulosin, alfuzosin and silodosin -- that improve urine flow and reduce frequency because they're more selective to the urinary tract.

Another option is to decrease prostate size with a medication -- finasteride or dutasteride -- that reduces the formation of the hormone dihydrotestosterone, or DHT. This hormone stimulates the prostate to grow; the medications work by inhibiting the enzyme that produces it. Note, however, that these drugs can take six months to one year to reduce symptoms; the biggest side effects are a lowered libido and, less commonly, erectile dysfunction.

A daily 5-milligram dose of the erectile dysfunction drug Cialis can also reduce symptoms of an enlarged prostate. Lastly, in those who don't retain urine in the bladder, anticholinergic medications such as tolterodine and oxybutynin help relax the bladder and decrease the desire to urinate. The problem with these medications is that they have more side effects, including dry mouth, blurred vision, drowsiness, constipation and impairment of mental function.

Because you mention surgery, I assume that you've already been given medication for your symptoms and are now confronting the prospect of a more radical intervention. The most common surgery for prostate enlargement is a transurethral prostatectomy. In this surgery, a urologist removes a portion of the prostate via the urethra. The transurethral prostatectomy is well-tolerated with minimal side effects, but if you're looking for a less invasive procedure, there are alternatives.

One alternative form of surgery -- known as focused laser ablation -- vaporizes prostate tissue with light waves. This eases symptoms immediately, has less blood loss than traditional surgery and has a recovery time of only two to three days. Although this procedure treats a smaller portion of the prostate, and symptoms may occur again at a later time, early research is supportive of this option. A European study in 2016, for example, showed that the benefits of this treatment lasted more than two years. Similar procedures use water vapor or even microwaves. All of these have fewer side effects than traditional surgery and have been shown to be effective.

Medications are obviously the first choice for symptoms of prostate enlargement. But if those don't work, there are less invasive procedures than traditional surgery.

(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 Reader: Some schools in my district are facing an outbreak of norovirus like you wouldn't believe. Why is it spreading so fast? What can I do to protect our family?

Dear Reader: Norovirus, which has earned the nickname "the vomiting bug," is extremely contagious. Add stomach cramps, fever, diarrhea and muscle pain to the list of symptoms and you get a good sense of the misery it causes.

It's the leading cause of gastrointestinal illness in the United States. About 21 million people get norovirus each year. Up to 70,000 of those land in the hospital, and about 800 die. And calling norovirus an "it" is misleading. There are actually many different types of norovirus, so getting sick with one kind doesn't offer protection from others.

The virus is shed in the feces of an infected individual. That means when someone with norovirus follows poor hygiene after a bowel movement, they spread it to everything that they touch. You can pick up norovirus by eating or drinking something handled by a contaminated person, by touching a contaminated surface and later putting your fingers in your mouth, or through close contact with someone who is sick. The virus is also present in a sick person's vomit, which adds another layer of risk when caring for sick children.

One of the reasons that outbreaks are so difficult to contain is that the norovirus is a hardy organism. It's impervious to hot and cold and to many disinfectants. When the virus gains a foothold in crowded and self-contained places like a school, hospital, nursing home or cruise ship, it spreads quickly.

Upping the ante is the fact that it can take up to a week for the norovirus that's already in your body to make you feel sick. And once your symptoms have ended, the virus can be found in your stool for more than two weeks.

So what do you do when norovirus hits nearby? Keep in mind that just because a neighboring school is affected, that doesn't automatically mean your child's will be as well. That said, there are several steps you can take to lessen the risk of infection.

-- All family members should wash their hands often. Use soap and running water and scrub for at least 20 seconds. Always wash after using the bathroom and before preparing food.

-- Carefully wash all fruits, vegetables and seafood before preparing them. Most outbreaks spread in food service areas, so when a norovirus outbreak is nearby, it's not a bad idea for your child to bring her own lunch and snacks to school for the duration.

-- Explain to your kids how the virus is transmitted. That will help them understand these rules: no fingers in the mouth (always a good idea at any time), and no sharing food or drinks with anyone, even if they don't look sick.

-- If someone in the house does become ill, use a bleach-based disinfectant to clean any surfaces contaminated by vomit or diarrhea. Don't forget door and drawer knobs, the fridge and the TV remotes.

-- If you're the one who's sick, don't prepare, cook or serve food for others.

(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.)