Summer is coming, and with it an increasing number of cases of this potentially devastating disease-which is spreading at an alarming rate. Fred Hammersmith, a Midwestern farmer, noted an expanding circular rash on his shoulder. His wife,alerted by reports in the local newspaper about a tick-borne disease, realized the rash might be the hallmark of Lyme disease. A three week course of oral tetracycline resolved Fred’s Lyme infection without complications.
Several years after being treated for Rocky Mountain spotted fever, Mary Leonard developed problems with her left knee. Steroids eased the inflammation and stiffness, but Mary couldn’t walk without crutches. A rheumatologist ordered blood tests. They showed she’d been exposed to the bacterium that causes Lyme-undoubtedly the real cause of the chills and fever she’d been treated for earlier. With IV penicillin her condition began to improve. Though she experienced several relapses, she now walks normally.
An active 9-year-old, Jonathan Lee began having trouble concentrating in school. He was tired all the time, and his left hip hurt. His doctor considered such diagnoses as emotional trauma and Paget’s disease. When Jonathan was finally hospitalized, an astute intern suggested drawing a Lyme titer to measure the concentration of antibodies to the bacterium in his blood. The test results were positive, and IV antibioties were begun immediately. Within a few weeks Jonathan was ready to resume a full schedule of schoolwork and play.
Variations on these scenarios are being played out with increasing frequency in many parts of the country. A disease that did not even have a name a few years ago has now made its appearance in nearly every state. Between 1983 and 1986 some 1,500 cases a year were reported to the Centers for Disease Control; in 1987, 2,000 cases were reported in Wisconsin alone.
The public’s reaction to an outbreak often borders on hysteria, where everything from flu to summer doldrums is suspected of being Lyme disease. It’s past time for nurses to know the facts about the disease and to help communicate them accurately.
What is Lyme disease?
In the mid-1970s, researchers investigating a cluster of arthritis cases in children living in the area around Old Lyme, Conn., named the puzzling disease Lyme arthritis. It soon became clear, however, that arthritis was only one manifestation of a syndrome that includes cardiac and neurological complications as well.
The carrier of the disease was identified as a tiny deer or bear tick called Ixodes dammini. As it feeds, the tick infects its host with the spirochete Borrelia burgdorferinamed for Willy Burgdorfer, the scientist who initially recognized the organism. The western blacklegged tick, I. pacificus, was later tied to the disease on the West Coast, and two or three other ticks have now been implicated as well.
This baffling disease has few certainties in its presentation. Most people bitten by an infected tick never get sick. Many of those who do contract the disease don’t develop the characteristic skin rash. And a person may present in the later stages of the disease without ever experiencing the early symptoms.
Like some other spirochetal illnesses, Lyme disease has been divided into stages. Asymptomatic periods may separate them, or they may overlap.
Stage I. Within a few weeks of the tick bite a rash may appear at the site. Called erythema migrans (EM), it varies greatly in appearance. The classic rash resembles a bull’s eye or target, but a great many don’t fit this pattern, and more variations are seen each year. The less typical rashes are easily confused with hives or cellulitis.
Even the classic rash varies greatly in size. It is usually painless, though it may feel hot, burn, or itch. The most common locations are the moist areas of the groin and armpit, or behind the knee. You may see secondary lesions, similar to the primary ones, on other parts of the body, and the lymph glands may be swollen. The rash may go away in a few days or last for a month or more. If Lyme disease is untreated at this stage, the lesions may reappear later.
Patients often experience malaise, fever and chills, nausea, headache, stiff neck, joint pain, or low back pain. Some of these symptoms come and go from hour to hour, and are so commonplace that patients with early-stage Lyme disease are often diagnosed as having the flu or a viral illness. Like the rash, flulike symptoms may recur.
Stage II. Complications in the second stage of the disease are more serious. Some 10% of patients develop heart block or other cardiac problems. Symptoms include weakness, lightheadedness, chest pain, and dyspnea upon exertion.
Another 10% will have neurological disturbances, most often Bell’s palsy-a sudden paralysis of one side of the face. The paralysis is temporary in 95% of treated cases.
An occasional patient develops aseptic meningitis, encephalitis, or polyradiculitis. Second-stage Lyme disease can also mimic GuillainBarre syndrome and benign intracranial hypertension. In these cases there tend to be spontaneous remissions and relapses.
As with syphilis, another spirochetal disease, Lyme disease may damage the eye through inflammation including conjunctivitis, iritis, and optic neuritis.
Stage III. Manifestations of third-stage Lyme disease may occur as early as four weeks after the bite or years later. Arthritis characterizes this stage. It usually involves the larger joints-the knee, ankle, hip, elbow, or wrist. About half the victims of Lyme disease experience arthritic episodes; some 10% develop chronic joint pain.
If Lyme remains untreated long enough, chronic neurologic problems may develop. The symptoms are not well-defined but include severe fatigue and muscle weakness, numbness or pain in the arms or legs, and short-term memory loss.
As with other spirochetal illnesses, Lyme disease has the potential to cross the placenta and harm the fetus. A pregnant woman who suspects she’s been bitten by a tick should call her obstetrician for advice.
Diagnosis and treatment
It’s easy to see why Lyme disease is so often mistaken for other illnesses. Unless a patient remembers being bitten by a tick or develops EM, it’s nearly impossible to diagnose early-stage Lyme disease. Blood tests are not helpful until antibodies form, some four to eight weeks after exposure. Even then, tests are not standardized and are sometimes inconclusive. False negatives and lab errors do occur.
On the other hand, a positive test does not necessarily mean that the patient has the disease; it simply indicates the presence of antibodies to the Lyme disease bacterium. Each institution has its own reference value for a titer range that indicates current infection.
Most patients with second- and third-stage Lyme disease will have clearly elevated Lyme titers. Aspirated fluid from an arthritic joint may contain fibrinous exudates, white blood cells, and immune complexes. Biopsy of the synovium may show lymphocytic infiltrates.
Antimicrobial protocol. Though it’s agreed that antibiotic therapy is the proper treatment, the precise regimen may vary from institution to institution. The following protocol is the one we use at the Marshfield Clinic:
If the patient presents during Stage I, a 21 -day course of oral antibiotics is prescribed. The treatment of choice for adults is 100 mg of doxycycline bid; alternatively, 500 mg of penicillin V potassium (Pen-Vee K) may be given qid orperhaps less effective-500 mg of erythromycin qid.
Children over the age of eight receive the same course as adults, with dosage adjusted to weight. A younger child is given a 21-day oral course of 50 mg/kg of Pen-Vee K daily, 125 mg/kg of amoxicillin tid, or 40 mg/kg of erythromycin qid.
During Stages 11 and 111, patients who are acutely ill receive a 14-day course of intravenous antibiotics. Adults are given 24 million units of IV penicillin or 2 grams of ceftriaxone (Rocephin) daily, Children receive 250,000 units of IV penicillin or 100 mg/kg of ceftriaxone daily.
In late-stage cases where chronic neurologic problems have developed, adults take 100 mg of doxycycline bid, 500 mg of tetracycline qid, or 500 mg of penicillin qid in a six-week oral course. Children receive weight-appropriate doses of the adultmedication orally for six weeks or a 14-day IV course.
Prognosis. If they are treated during Stage 1, most victims recover completely. If the disease progresses to the later stages, some tissue damage may be irreversible. It is not known whether the damage is done by the spirochete itself or the immune system’s response.
Even with adequate treatment, however, symptoms can recur, although later attacks tend to be less severe. Follow-up blood tests showing declining Lyme titers are considered an indication that the illness was successfully treated. Some patients, however, continue to show an elevated titer, and clinicians are unsure about the significance of those elevations. Although one bout of Lyme does not confer immunity, it is thought to make the patient more resistant to the disease.
Ounce of prevention is the best protection
The I. dammini tick, a member of the spider class, lives in grassy, sandy, and wooded areas. During its two-year life, it survives by sucking blood from warm-blooded animals. If the larval tick feeds on a spirochete-infected mammal-its favorite prey is the field mouse-it can pass on the infection during either of the next two stages.
It’s during the nymphal stage that the tick is most likely to choose a human restaurant, attaching itself to an unsuspecting person walking through tall underbrushor even across the lawn. Ticks don’t fly or jump onto a host. Instead, they wait on top of vegetation until a mammal brushes by, then attach themselves to skin, fur, or clothing. The adult tick generally feeds on larger mammals like deer.
To feed, the tick attaches its mouth to the host, a process that usually takes from six to 12 hours. If it can be removed during this time, it probably will not infect its victim. Once attached, it sucks its meal for from one to three dayssometimes for up to a week. Typically, the tick feeds painlessly and drops off unnoticed.
Pets can also bring home the disease: An unattached tick may brush off a dog or cat onto its master. Small wild animals and birds may deposit ticks in the backyard. The spirochete has also been found in horse flies, deer flies, fleas, and mosquitos, but we don’t know if these insects are capable of transmitting the disease.
It’s possible to get Lyme disease at any time of year, but the incidence-at least in the northern part of the country-is greatest from May through August, when people spend more time out of doors and wear fewer clothes, and the tick is in the nymphal stage.
Preventing tick bites. In a tickinfested area, your best protection is to wear sturdy shoes, long pants with cuffs tucked into socks, and long-sleeved shirts with cuffs-not the most comfortable attire in the middle of summer, to be sure. You’ll be able to spot ticks more easily if your clothing is lightcolored.
You can protect yourself further with tick-repelling sprays that contain permethrin (Permanone) or D.E.E.T. Be sure to apply the spray to clothing, not directly on the skin. Put flea and tick collars on pets.
Try to avoid walking where you will brush against low vegetation. Keep the lawn and shrubs around your home trimmed.
Inspecting for ticks. When you return home make it a habit to conduct “tick cheeks” on yourself, your children, and your pets. Remember that ticks like to feed in creases.
If you find a tick, grasp it firmly with fine tweezers as close to the skin as possible. Gently but firmIy-the tick’s mouth parts have barbs-pull it straight out. Don’t grab its bottom or crush it, or you may inject the spirochetes into the bite. Thoroughly wash the bite area and your hands with an antiseptic solution. Consult your physician if you’re unable to remove the tick completely.
Save the tick, wrapped in a moist piece of tissue paper, in a jar labeled with the date, the location on the body from which you removed the tick, and the place where you think you picked up the tick. If you develop a rash or flu-like symptoms, your physician may be able to have a lab cheek the tick for spirochetes to help confirm a diagnosis. Even if you have no immediate problems, remember the tick bite if you develop mysterious symptoms in the future.
The patient who gets Lyme disease today is luckier than his counterpart of a decade ago. We know what causes Lyme, we’re getting better at recognizing its manifestations and we can usually treat it effectively. In time, our testing methods will improve, and a vaccine may someday be developed.
Such advances are no cause for complacency, however. This year many more people than last year will contract Lyme disease, and many of them will be misdiagnosed or untreated. The facts you know about the disease will help your patients get proper treatment-and maybe even prevent a case or two.