Sure, but as long as they don’t get attached to your body

It shouldn’t have surprised me when my dog tested positive for Lyme disease on bloodwork obtained before my vet administered the vaccine. Boomer wasn’t symptomatic, but he spends a lot of time in the woods. Local ticks have shown an upsurge in carriage of the Lyme organism “Borrelia bergdorferii” over the past several years.

Ticks are fascinating little critters, at least when not attached to your body. There are over 800 species of ticks worldwide, which attests to the success of their lifestyle as blood suckers. Their life cycles are complex, as illustrated by the story of a typical deer tick “Ixodes scapularis,” the usual vector for Lyme disease around here.

Deer tick eggs in the soil hatch into larvae in the summer, and begin seeking their preferred host, the white-footed mouse. These larvae are the size of the period at the end of this sentence and have only six legs. Successful larvae feed on the mouse’s blood, then drop off and overwinter on the forest floor. In the spring these larvae molt into eight-legged nymphs that crawl onto vegetation and hang out waiting for larger vertebrates to happen by so that they can feed. This is the stage where a hapless human being may become the tick’s next meal.

The nymphs who successfully obtain a blood meal drop back to the forest floor and molt into adults. The adults look for their preferred host, the white-tailed deer.

Upon finding a deer, the ticks fuel their reproductive strategy with a meal of deer blood. The happy tick couples mate on the deer and each female produces several thousand eggs! These eggs fall to the soil and start the process anew. That’s why the more deer in an area, the more likely the area is to harbor deer ticks, and the higher the risk that a human will be bitten.

In order transmit Lyme disease, the tick must feed for a while, then regurgitate some of its stomach contents back into the host’s bloodstream. Fortunately this usually requires that the tick be attached for more than 24 hours, so daily tick checks are essential for those who spend time outdoors.

On the other had, hard-bodied ticks have evolved mechanisms to help escape detection: anticoagulants to keep the blood flowing for as long as needed, anti-inflammatory substances to make the bite painless so host doesn’t feel the tick, and immunosuppressive compounds to prevent detection by normal host defenses.

While Lyme disease is the most common tick-borne disease, ticks can carry other illnesses such as erlichiosis, babesiosis, and others.

So ticks have size and stealth in their favor. We humans can try to prevent tick bites by tucking in our pants, using insect repellent, avoiding grassy vegetation where ticks hide, and wearing light-colored clothing to permit early tick detection. If you do find an attached tick, the best removal method is a gizmo called a tick twister. Second best is to grab the tick with a pair of tweezers as close to the head as possible and to pull straight back.

Sometimes the mouthparts break off and are left behind, and can be picked out with a needle like a splinter. Leaving the mouthparts behind does not increase the risk of disease transmission. And the mouthparts are small and superficial enough that they will work their way out in a few days. So unless they are bothering you (an occasional person has an allergic reaction or local infection), nothing awful will happen to you if you leave the tick mouthparts in place.

Should you send the tick to the lab? The New York State Tick Identification service will tell you the species of tick and whether it is engorged (something you can see for yourself and provides only a guesstimate of how long the tick may have been attached.) They will not tell you whether the tick was carrying any disease.

As a physician, I’ve found that waiting a few days for this information isn’t very helpful in making treatment decisions. If an attached tick is removed, a brief course of an antibiotic is effective in preventing disease transmission.

What about bloodwork? Current lab tests look at whether a patient has formed antibodies to the Lyme disease organism. The blood test takes several weeks to become positive. It can assist in diagnosing Lyme disease, but it doesn’t help decode what to do for a tick bite with no symptoms.

The symptoms of Lyme disease are tricky; the majority of people diagnosed with Lyme disease don’t recollect any tick bite! The initial manifestation, a rash called erythema migrans, occurs in 75 percent of infected people but is often overlooked since it seldom hurts or itches. It’s typically described as a spreading ring with central clearing that makes it resemble a target. But, here in the United States, most rashes never get the classic central fading! The rash begins one day to one month after the tick bite, can last up to several weeks, and may be tiny to as large as 70 cm .across.

Later symptoms of Lyme disease fall into several categories:

• Neurologic: headache, stiff neck, facial nerve weakness called Bell’s palsy, sensory changes, and meningitis.

• Cardiovascular: Blockage of the heart electrical system, and inflammation of the tissues surrounding the heart.

• Musculoskeletal: arthritis, and muscle tenderness.

• Eye: inflammation in the cornea, conjunctiva, and iris, and bleeding into the retina.

So you can see why the disease may be hard to diagnose. There currently is no human vaccine available.
At least another tick borne disease, relapsing fever, is found in the west and not here in the northeast. It’s caused by soft-bodied ticks which feed for only an hour before dropping off, thus easily escaping detection.

Most affected individuals have stayed in rodent-infested cabins, which I find very comforting after a recent escapade in which my husband forgot to tell me that he had (accidentally) let a chipmunk in the house until I pulled back the covers and found it in my bed. I’m not making this up. You can ask my cat, who lazily watched the ensuing pandemonium without so much as lifting a paw to help.