Remember — don’t get ticked off, [just] get the tick off!
Every summer ticks make headlines, mostly because of their notorious ability to spread disease. Thus, for the month of May, we asked our friend Dave Simser to produce an article for publication here. It’s a little bit on the technical side, but this is some good general information to keep you in the know and to mitigate the dangers associated with ticks. (Intro by Mike Cherim.)
It’s Tick Time
Of the 800 or so species of hard ticks in the world, and about 80 US species, just three are important to residents living east of the Mississippi River. Although several other tick species can and do bite humans, these three are responsible for most cases of tick-borne diseases, including anaplasmosis, babesiosis, human monocytic ehrlichiosis, Lyme disease, Rocky Mountain spotted fever and several others. This trio of medically important ticks includes the American dog tick (Dermacentor variabilis), the lone star tick (Amblyomma americanum) and the blacklegged tick, also known as the deer tick (Ixodes scapularis).
In fact, Lyme disease, transmitted by the deer tick, is the foremost arthropod associated disease in the US and thus the deer tick may be regarded as one of our more important disease-carrying pests. Each year over 20,000 people in the US are infected by this persistent, debilitating illness, and are treated with antibiotic therapy. Early treatment generally offers resolution and the illness is cured. However, if untreated, many persons must live with the consequences of chronic Lyme disease and endure constant arthritis, fatigue and other serious symptoms without apparent remedy. In the east, this disease is only carried and transmitted by the minute deer tick.
This tick has a two-year life cycle that includes an egg stage, a six-legged larva, an eight-legged nymph, and the adult male or female. In a generation, the larvae hatch in early August and seek a blood meal, usually provided by an unsuspecting small mammal or bird scuttling about on the forest floor. The tiny larval tick snags on a hair or feather, climbs aboard and settles to dine. After feeding for several days, the larval deer tick drops from the host and molts (develops) to a non-feeding flat nymph, spending fall and winter months in this stage.
In early to mid-May, the nymphs activate and again quest for blood from a small mammal, bird, pet or a human. Deer ticks are patient hunters, remaining stationary until a small host is within grasp. After noshing for about 4 days, the nymphs drop off, molt into an adult tick and emerge in late September to early October. Although the adult ticks crave a larger mammal, particularly white-tailed deer, they will also feed on a human or a pet. Adult ticks can be active during winter months whenever the temperature is above about 40°F. Because two separate generations can overlap, both adult and nymph deer ticks may be active in May and June.
Deer ticks are a nuisance pest, as their attachment and feeding is annoying and produces a splintered tenderness at the wound, but their role as a disease carrying vector makes them a health concern, as they can transmit microbes into the wound site. Deer ticks need a reservoir host mammal, such as a chipmunk or field mouse, in order to acquire the Lyme disease microbe. Once infected, ticks remain so during subsequent stages. In some areas, about 20% of nymphs and about 50% of adult female ticks are infected with Lyme disease.
The active nymph period from May to August is regarded as the key risk period, since nymphs may be infected, and are just so tiny (poppy seed sized). They may crawl up the leg of a gardener, hiker, or outdoor enthusiast and settle in an obscure area such as the back, backside, or head. The tick then saws through the host skin using the specialized chelicerae [mouth parts], inserts the barbed hypostome [feeding] tube and prepares to siphon blood.
The wound is desensitized by compounds produced by this hungry parasite, including desensitizing analgesics, anticoagulants to ensure blood flow and a strong secure glue to lock the tick firmly to its meal. If the tick is infected with Lyme disease, the disease organisms, known as spirochetes, must pass from the mid-gut into the hemolymph (tick blood) and then migrate into the salivary glands, where this pathogen is passed along with tick saliva back into the unsuspecting meal giver!
Deer ticks reside primarily in wooded areas where deer are plentiful, like most of the northeastern forests. The coastal states including Rhode Island, Connecticut and Massachusetts traditionally yield the highest rates of Lyme disease in humans (as does New York), but this ailment has been recorded from all states. The reader is thus advised to be on alert — constant vigilance — when in suburban, rural or wooded areas in the Northeast.
Prevention is the key to reducing the risk from an infected tick. Check yourself whenever duties bring you to the garden, yard or forest. Should you feel a small scab on your back or head, ask for assistance in inspection. If a tick has found you, remove it by grasping close to the attachment point (fine tip tweezers work best) and pulling back with steady pressure. Wipe an antiseptic on the wound site and have the tick identified. Some state agencies can provide tick-testing services, or guide you to such a site.
If you have had a tick attached for more than 36 hours, you may be infected with Lyme disease. A trip to the doctor is warranted should you develop an expanding rash near the tick site. This red circular sign occurs in about half of the early cases of Lyme disease, generally followed by aches in the major joints, tiredness and overall flu-like symptoms. Note that a person can acquire the disease without getting (or seeing) the rash.
In summary, if you suspect Lyme disease in you or a loved one, please see a doctor. Don’t assume it’s a summer cold and will “go away.” Remember — don’t get ticked off, [just] get the tick off!
Our long-time friend Dave Simser is a board-certified entomologist for over (gulp) 25 years and has been working with ticks since 1998. Dave’s a nice guy with long hair who works and lives in Massachusetts.
Photo courtesy of The New York Academy of Sciences.
Mike Cherim responds:
Posted: June 18th, 2007 at 2:34 am →
Excellent information. Thanks Dave.