Saliva is a key defense from toxins
Q: Our 9-year-old loves science and has become obsessed with saliva. He recently learned in school it helps prevent disease, and now he wants to know more. My wife and I are glad he's curious and hope you can help. What is saliva? Does it really help people stay healthy?
A: Your budding scientist has asked a great question. When you think about the many ways our bodies protect us from potential danger, saliva isn't the first thing that generally comes to mind. And yet, it's a crucial line of defense.
It makes sense, considering the mouth is a key entryway for potential pathogens. These include dangerous microorganisms or toxins that may be contained in food or drink, as well as those that can hitch a ride into the mouth on fingers, surfaces, objects or even a kiss. And while we rarely think about the constant presence of saliva in our mouths, it's actually a pretty remarkable substance.
While awake, a healthy person produces two or more pints of saliva per day. During sleep, however, that amount drops to near zero. The majority comes from three major pairs of salivary glands, with additional amounts coming from an array of hundreds of minor glands. The fluid these glands produce lubricates the mouth and throat, moistens food so that it can be chewed and swallowed, makes possible the sense of taste and washes away particulates. Because saliva has a near-neutral pH of 6.3, it helps protect tooth enamel by maintaining the acid-base balance in the mouth. And while it's made up of 99% water, the remaining 1% contains a number of important organic and inorganic molecules. That makes saliva a biofluid.
Some of the compounds in saliva, including the enzymes lipase and amylase, kick-start the process of digestion by beginning to dismantle fats and carbohydrates the minute you begin to chew. And others, as your son has learned, play an important role in protecting the body from disease. Saliva is stocked with an array of antiviral, antimicrobial and antifungal compounds. These include hydrogen peroxide, lactoferrin and strings of simple proteins that dismantle, damage and neutralize many potential pathogens.
Recent research has revealed tiny sugar molecules found in saliva, known as glycans, play an important role in preventing a certain fungus that is present in the mouth from becoming a health problem. Saliva also contains certain compounds that play an important role in wound healing. If you've noticed that when you accidentally bite your tongue or chew your cheek, the injury heals surprisingly fast, saliva is the reason.
We'll wind things up with a quick mention of the potential of saliva as a diagnostic tool. Some readers may have already undergone a so-called “spit test” for COVID-19, which identifies the SARS-CoV-2 virus more quickly (and comfortably) than testing with nasal swabs. Researchers are also learning that various proteins and other compounds in saliva become detectably altered in response to certain types of disease. These discoveries have led to a promising new screening test for oral precancers and cancers.
Q: Ticks are a big problem where we live in Pennsylvania. Our family loves being outdoors, so staying away from tick territory isn't an option. One thing I really want to know is the right way to remove a tick when you get bitten.
A: We're glad to get this question because the United States has seen a surge in reports of tick bites and tick-borne illnesses in recent years. This is due to heightened awareness, an increase in tick populations and an expansion of their range. At the same time, the easing of pandemic constraints has led to an increase in outdoor activities. The upshot is that more people are encountering more ticks than ever before.
Ticks bite mammals because they require a blood meal to advance through each of their three stages of life. To complete their two- to three-day feed, they are outfitted with a trio of complex mouthparts. These include telescoping rods, hooked teeth and a “straw” lined with backward-facing barbs through which it sips blood. The tick uses its mouthparts to pierce the skin, latch on and bury its head. You don't feel the bite due to painkillers in the tick's saliva. The point of all this (unsettling, we know) detail is to help you understand what you're working to undo as you remove a tick.
The goal in extracting a tick is to pull its head out of the flesh without damaging or squeezing its body. The best tool for this is a pair of tweezers with pointy ends. These give you a precise grip and good leverage. Start by washing your hands and sterilizing the tweezers with rubbing alcohol. Then place the slender tips of the tweezers as close to the skin as possible, on either side of the tick's head. Gently pull up, using steady and even pressure. You're pulling those backward-facing barbs from the skin. Be sure not to twist, turn or jerk as you pull or the head, or mouthparts might be left behind in the skin. Once the tick is free, check that it's whole. If undamaged, its legs will move. If the tick breaks and you can't retrieve the head or the mouth, it is advisable to seek medical help to remove it.
Wash the bite thoroughly with soap and water. Secure the tick in a plastic bag or bottle so that, should you develop symptoms in the next 30 days, it can be examined. Tick-borne diseases can have similar symptoms, including fever, chills, rash, nausea or vomiting, fatigue, headache and body aches. Keeping the tick allows it to be examined and a specific virus or bacterium to be identified, and then the appropriate treatment can be prescribed.
Meanwhile, take precautions. In wooded areas, wear long pants and long sleeves, and tuck in your shirt and pant cuffs. Light colors make ticks easier to spot. Use insect repellent with 20% to 30% DEET on clothes and exposed skin. Be sure to follow the product instructions. End all outdoor activities with a thorough tick check.
If you have been bitten by a tick and develop symptoms, it's important to seek medical care.
• Dr. Eve Glazier is an internist and associate professor of medicine at UCLA Health. Dr. Elizabeth Ko is an internist and assistant professor of medicine at UCLA Health. Send your questions to askthedoctors@mednet.ucla.edu.