Bannwarth or Garin-Bujadoux syndrome. The identity of these diseases has been established, as well as their close relationship to relapsing fever—a disease that is also caused by spirochetes of the genus Borrelia and transmitted by ticks. The entire group is now classed as the borrelioses but there are notable clinical and serologic differences between the American and European varieties of the disease.
In humans, all these spirochetoses, if untreated, induce a subacute or chronic illness that evolves in ill-defined stages, with early spirochetemia, vascular damage in many organs, and a high level of neurotropism. As in syphilis, the nervous system is invaded early in the form of asymptomatic meningitis. Later, neurologic abnormalities appear, but only in small a proportion of such cases. The early neurologic complications are mainly derivations of meningitis. Unlike syphilis, peripheral and cranial nerves are often damaged (see further on and Chap. 43). Immune factors may be important in the later phases of the disease and in the development of the neurologic syndromes.
Lyme disease is less acute than leptospirosis (Weil disease) and less chronic than syphilis. It successively involves the skin, nervous system, heart, and articular structures over a period of a year or longer although one aspect or another may predominate. The responsible organism, as stated earlier, is the spirochete B. burgdorferi and the vector in the United States is the common deer tick (Ixodes dammini). The precise roles of the infecting spirochete, the antibodies it induces, and other features of the human host response in the production of clinical symptoms and signs are not fully understood, but the development of an animal model by Pachner and colleagues suggests that there may be a chronic form of Borrelia infection.
Lyme borreliosis has a worldwide distribution but the typical neurologic manifestations differ slightly in Europe and America, as emphasized in the review by Garcia-Monico and Benach (as does the serologic testing). In the United States, where approximately 15,000 cases are reported annually, the disease is found mainly in the Northeast and the North Central states. Most infections are acquired from May to July. In 60 to 80 percent of cases, a skin lesion (erythema chronicum migrans, or erythema migrans) at the site of a tick bite is the initial manifestation, occurring within 30 days of exposure. It is a solitary, enlarging, ring-like erythematous lesion that may be surrounded by annular satellite lesions. Usually fatigue and influenza-like symptoms (myalgia, arthralgia, and headache) are associated, and these seem to be more prominent in the North American (B. burgdoferii) than the European form of the illness (Borrelia afzelii and Borrelia garinii)—possibly attributable to a more virulent species of spirochete (Nadelman and Wormser). This assumes importance in patients who may have acquired the illness in another part of the world in whom the correct diagnosis may be missed if the specific antibody for the regional organism is not sought. The European variant has a propensity to cause the painful lymphocytic meningoradiculitis, Bannwarth syndrome, as summarized in the review by Pachner and Steiner.
Weeks to months later, neurologic or cardiac symptoms appear in 15 and 8 percent of the cases, respectively. Still later, if the patient remains untreated, arthritis or, more precisely, synovitis develops in approximately 60 percent of the cases. Death from this disease does not occur; consequently, little is known of the pathology. A long period of disability is to be expected if the disease is not recognized and treated.
Diagnosis is not difficult during the summer season in regions where the disease is endemic and when all the clinical manifestations are present. But in some cases, a skin lesion is not observed or may have been forgotten, or there may have been only a few or no secondary lesions and the patient is first seen in the neurologic phase of the illness. Then clinical diagnosis may be difficult.