Lyme Disease
by Dr. Paul Pomilla

I. HISTORY

Lyme disease was first named in 1977 because of a geographic cluster of arthritis in children in Lyme, Connecticut. However, in retrospect, the first descriptions were probably those made in the 19th century of a condition called “Montauk knee”, occurring among the citizens of Montauk, Long Island, New York. In 1982, Burgdorfer and others isolated the previously unrecognized spirochete (a type of bacteria) from Ixodes dammini (deer ticks) which causes Lyme. That spirochete is now called Borrelia burgdorferi in honor of its discoverer.

                      Deer Tick in 4 stages

   Deer Tick, Actual Size

II. TRANSMISSION

The life cycle for the “Lyme bacteria” (Borrelia burgdorferi) is complex. The bacteria can live in the bloodstream of the white-footed mouse (Peromyscus leucopus) without making the mouse sick. (Most wild animals don’t seem to get sick from the Lyme bacteria, although domestic animals such as dogs, cattle, and horses can).  The larval (immature) deer tick (either Ixodes dammini or a closely related species) prefers to attach to the white-footed mouse (Peromyscus leucopus) and feed on the blood of the mouse; feeding on an infected mouse will cause the Lyme bacteria to enter the gut of the tick, without making the tick ill.

 When the tick grows into its’ next stage, the “adolescent” nymph stage, the Lyme bacteria migrates to the tick’s salivary glands and are injected with saliva as it feeds. Usually it needs to be attached to its’ host for 24 hours or more before it can transmit the Lyme bacteria. Often the nymphal tick will attach to the white-footed mouse, infecting it, and resuming the cycle.

Finally, the infected (but not ill) tick becomes an adult and prefers to attach to white-tailed deer (although they can attach to other animals). The deer may bring the tick into closer proximity to humans and the tick may then, incidently, attach to a human and transmit the Lyme bacteria to the human.

III. SYMPTOMS

Bulls-eye rash associated with Lyme disease.

Lyme can cause a variety of symptoms in humans. The first symptom it causes is a rash at the site of inoculation (that is, the tick bite site). This rash occurs in most, but not all, patients who develop Lyme and occurs within a month after inoculation (and usually within 1-2 weeks after the bite). It usually is fairly circular, larger than a half-dollar, and has a “bull’s eye” appearance, but it may not have any of these features. Here is an example:

Sometimes the patient may experience fever or flu-like symptoms during this time, but often there are no symptoms at all except for the rash. The rash usually fades (most commonly in 1 month), even in patients not treated. The rash may develop in other areas in patients who are not treated.The bacteria may then spread through the patients bloodstream or lymph system and infect the rest of the body, causing a variety of symptoms. During this time, generalized symptoms of fatigue and fever (usually low-grade) are more frequent.

The following is a list of some of the most common
organs infected and the associated symptoms:

Nervous system – it can infect the “peripheral” nerves (those in the extremities and torso) causing numbness and weakness and Bell’s palsy (short-term paralyis of half of the facial muscles). It can also affect the brain causing a (usually low-grade) meningitis and encephalitis characterized by neck stiffness, headache, and difficulty concentrating.

Joints – it may cause joint pain with or without swelling, most commonly in the knees, but any joint (although not usually the vertebrae) can be involved.

Heart – it can infect the conduction system of the heart, causing a slow heart rate (termed “heart conduction block” and not to be confused with blockage of the arteries, which Lyme does not cause).

Rarely, it will cause other symptoms not mentioned above. It generally does not cause respiratory symptoms (sore throat, cough, shortness of breath, etc) or gastrointestinal symptoms (abdominal pain, diarrhea, etc).

IV. DIAGNOSIS

            Because of the variety of symptoms, it can be difficult to make an accurate diagnosis of Lyme, especially for patients who have more than just the single rash. Overdiagnosis and underdiagnosis (that is misdiagnosis) are both common. Contributing to misdiagnosis are the following factors:

a.       Lyme can’t be simply cultured from an accessible body site, such as culturing a throat for strep infection. First of all, Lyme is often fairly inaccessible in nerve tissue, joints, cerebrospinal fluid and brain. Secondly, the Lyme bacteria is very different than the strep bacteria and takes several weeks to culture using special techniques – therefore, culturing is done only as a research tool and is not generally available or helpful.

b.      Because it can’t be cultured, we usually rely on indirect evidence of it’s presence by testing for the patient’s antibody response to the Lyme (the same way we often test for viruses, which present some of the same diagnostic difficulties). However, it may take time, usually three weeks or so, for an antibody response to be detected. Furthermore, treating before the antibody response occurs (for example, treating as soon as the classic rash appears) may prevent an antibody response from ever developing. Finally, in most cases, the antibody level is positive for life, even though the infection may be gone (this also is true with viral infections – after all, one of the purpose of antibodies is to prevent further infections from the same organism). Therefore, there is no blood test that can prove cure.

            Because of these difficulties, one cannot completely rely on blood tests for diagnosis in every case. Furthermore, two blood tests are commonly done (as is done in HIV testing also) – an initial inexpensive blood test that can be done at most labs and which doesn’t generally miss any cases of Lyme (is highly “sensitive”) but may also be positive in cases that aren’t Lyme (is not “specific”). Therefore, it is used as a screening test – if it is positive, then the blood is sent to a reference lab that has the expertise to do a more specific “Western blot” test, that tests for several different antibodies to Lyme. If the screening test is positive, but the confirmatory Western blot is negative, the blood test is interpreted as being negative. In many cases it is not useful to even do a blood test – for instance, if a patient has just developed the classic rash and has no other symptoms, it is appropriate to treat the patient immediately, rather than wait several weeks for the blood test to become positive.

V. TREATMENT

            Treatment varies depending on symptoms and organs involved. It should be noted that some people probably get asymptomatic infections or infections that are controlled by their immune systems. For instance, 3% of people living in Lyme, Connecticut who experience no symptoms have blood tests positive for Lyme. It is thought that treatment would not be useful in this case, unless symptoms develop.

            For patients who only have a single rash, 14-21 day treatment with doxycycline, amoxacillin, or cefuroxime (“Ceftin”) is standard. For patients with additional symptoms, including fever, muscle and joint aches, and Bell’s palsy, treating with antibiotics for 30 days is appropriate. For selected patients, especially those with symptoms of meningitis, encephalitis, significant arthritis or peripheral nerve symptoms; or those not responding to oral antibiotics, three to four weeks of intravenous antibiotics – usually ceftriaxone (“Rocephin”) – is recommended by experts. Such long-term intravenous antibiotics are most commonly administered at home via a special long IV’s inserted through a vein in the elbow area of the arm. Such Midline or PICC (“peripherally-inserted intravenous central catheter”) catheters are occasionally inserted by a home agency nurse at home, but are more commonly inserted in the hospital outpatient department or radiology department by specially trained nurses and physicians. For patients with poor peripheral vein access or for those who desire or require more freedom of movement of their arms during the month of treatment, a central venous catheter inserted into a large vein in the chest by a surgeon may be desirable. This procedure can be done via Same Day Surgery.

            Complications of either type of catheter include bloodstream infections or local site infections, and blood clots, although fortunately neither complication is common. Complications of IV antibiotics include generalized fatigue, diarrhea, oral or vaginal yeast infections. Bone marrow, kidney, and liver damage are rare, are generally reversible, and are monitored for by weekly blood tests.

            It should be noted that there is some controversy regarding appropriate length of treatment for Lyme disease, although this controversy exists more on internet sites than among recognized Lyme experts or the Infectious Disease Society of America. This controversy probably exists for several reasons:

a.      Some Lyme symptoms persist even after treatment is completed, or in a few cases, indefinitely. This is because once damage is done to, for instance, joint cartilage (whether that damage is due to Lyme or an injury or other causes of arthritis) the cartilage and the joint are permanently damaged. Likewise, repair of peripheral nerves, if it occurs at all, may take several months to years.

b.      As noted above, there is no test of cure of Lyme. However, the evidence strongly suggests that one month of antibiotics invariably eliminates the organism, if not always the symptoms. The most convincing evidence to date was published in the New England Journal of Medicine in 1994. In that study,  patients with Lyme  arthritis had joint fluid removed and tested directly for Lyme DNA. No patients who received twenty-one days or more of an appropriate antibiotic had detectable Lyme DNA in joint fluid after treatment (although a small percentage still had symptoms).  Furthermore, no other spirochetal infection requires more than one month of antibiotics for cure. Although more confirmatory evidence would be welcomed, I follow CDC guidelines and expert opinion and generally treat for no more than one month. Patients interested in being treated longer for persistent symptoms should contact the National Institutes of Health, which is conducting research into this.

V1. PROGNOSIS

            Most patients with Lyme get better. It is sometimes difficult to appreciate that because of “publication bias” – the rare patient who doesn’t improve much is more likely to be written about or to make their situation known. However, even without treatment, many patients will improve (this information obtained from studies that followed patients with Lyme diagnosed in the late 1970’s and early 1980’s, before treatment was available). However, antibiotic treatment clearly improves those percentages, and works better the earlier the infection is detected. In one study of 201 young patients with Lyme (including those with meningitis and arthritis) placed on antibiotics, 94% were symptom-free at the end of treatment, and 100% were symptom-free two years later. Even with later-stage symptoms, careful studies indicate that most patients improve or resolve their symptoms.

 LYME MISCONCEPTIONS

Lyme is a fatal disease – Not true; excluding one or two very unusual cases. Even Lyme involvement of the heart is readily and easily treatable.

If you get bit by a tick, you should take an antibiotic – No; the risk of developing Lyme is about 1% if you are bitten in an area with high rates of Lyme (like Calvert County), less so if the tick is attached for less than 24 hours. There is no convincing evidence that treating at the time of the tick bite will prevent infection. However, careful observation of the area, and other symptoms, is warranted and if the rash or other symptoms develop, one should seek medical attention promptly.

Lyme is the only disease transmitted by deer ticks – Not true; Ehrlichia is transmitted by the same type of ticks. Ehrlichia is a fairly recently described bacteria that causes a different set of symptoms than Lyme and generally more severe symptoms. Symptoms of Ehrlichia almost always include fever, but not always rash; it may cause a cough, and headache and other symptoms and can be fatal, but is easily treatable if recognized.

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