Mapping Lyme disease incidence for diagnostic and preventive decisions, Maryland

To support diagnostic and preventive decision making, we analyzed incidence of Lyme disease in Maryland on the zip code level. Areas of high incidence were identified on the Upper Eastern Shore of the Chesapeake Bay and in counties north and east of Baltimore City. These latter foci, especially, are not visible when mapping Lyme disease on the county level.

Prevention of tick-borne diseases

Ticks are a part of the landscape where humans live, work, and play. Because ticks carry a wide range of organisms that potentially can cause disease in humans, many studies have focused on ways to reduce risk of these diseases. Ticks have biologically complex interactions with microorganisms and with their vertebrate hosts, on whom they depend for blood meals and survival. To consider ways to reduce the burden of tick-borne diseases in humans, it is necessary to understand the biology and ecology of ticks and their interface with humans. In many areas, changes in land use, reforestation, and patterns of human settlements have led to more abundant tick populations, increasing rates of infections in ticks, and increasing contact with human populations. Warmer winter temperatures in temperate regions may extend the transmission season for some ticks and pathogens. Although much of the discussion in this article has focused on I. scapularis and the Lyme disease spirochete (because they have been studied extensively), other tick-pathogen pairs may differ in risk factors for infection and transmission dynamics. Interventions studied to reduce the burden of tick-borne diseases include changing the environment, controlling vertebrate hosts, killing ticks, altering the behavior of humans, treating tick bites, and trying to protect humans through immunologic means (vaccine). All of these approaches have limitations and drawbacks. From a public health perspective, a plan that employs multiple strategies may be most effective. This article has reviewed what is known about preventive interventions, including the vaccine.

Approaches toward the directed design of a vaccine against Borrelia burgdorferi

The overall efficacy of a recombinant vaccine for Lyme disease that is effective worldwide will depend upon the selection of one or more immunoprotective target(s) and the frequency of genetic variation, which can alter the antigenicity of the immunoprotective epitopes of the target proteins. Careful delineation of these protective epitopes on target antigens is essential for the development of vaccine candidates as well as for understanding the limitations of such vaccines. Structural models of these targets will provide critical information about conformation and specific residue surface accessibility for defining protective epitopes. Co-crystal structures with Fab fragments of protective antibodies will further delineate critical antigen surfaces. Population genetics will provide vital information on the heterogeneity of these proteins. Detailed epitope mapping will provide the information needed for the bioengineering of antigens needed to expand the specificity of a candidate vaccine.

Active immunisation against human tick-borne diseases

With the development and licensure of a recombinant vaccine for the tick-borne infection Lyme disease, more attention has been paid to other vaccines that have been used or are being developed for the prevention of other tick-borne infections. This review highlights vaccine information for Lyme borreliosis, tick-borne encephalitis (TBE), Rocky Mountain spotted fever, tularaemia, Query (Q) fever, Kyasanur Forest disease (KFD) and tick paralysis. Additionally, discussion on the use of immunisation against the tick itself is included which not only can decrease veterinary tick burdens but may also decrease the transmission of arthropod-transmitted diseases.

Vector interactions and molecular adaptations of lyme disease and relapsing fever spirochetes associated with transmission by ticks

Pathogenic spirochetes in the genus Borrelia are transmitted primarily by two families of ticks. The Lyme disease spirochete, Borrelia burgdorferi, is transmitted by the slow-feeding ixodid tick Ixodes scapularis, whereas the relapsing fever spirochete, B. hermsii, is transmitted by Ornithodoros hermsi, a fast-feeding argasid tick. Lyme disease spirochetes are generally restricted to the midgut in unfed I. scapularis. When nymphal ticks feed, the bacteria pass through the hemocoel to the salivary glands and are transmitted to a new host in the saliva after 2 days. Relapsing fever spirochetes infect the midgut in unfed O. hermsi but persist in other sites including the salivary glands. Thus, relapsing fever spirochetes are efficiently transmitted in saliva by these fast-feeding ticks within minutes of their attachment to a mammalian host. We describe how B. burgdorferi and B. hermsii change their outer surface during their alternating infections in ticks and mammals, which in turn suggests biological functions for a few surface-exposed lipoproteins.

Multilesional primary cutaneous diffuse large B-cell lymphoma responsive to antibiotic treatment

Borrelia burgdorferi infection has been implicated in cutaneous B-cell lymphoma. We report a case of multilesional primary cutaneous large B-cell lymphoma without extracutaneous spread in a patient with elevated B. burgdorferi titers. After antibiotic therapy, clinical remission and a subsequent drop in B. burgdorferi antibody titers were obtained.

Recombinant assay for serodiagnosis of Lyme disease regardless of OspA vaccination status

All current seroassays using cultured Borrelia burgdorferi as their antigen source have been rendered obsolete by the recombinant OspA Lyme disease vaccine. OspA is the major outer surface protein expressed in cultured B. burgdorferi, and any seroassay that uses whole organisms as its antigen source cannot differentiate between subjects who received the vaccine and those who were naturally infected. We developed a new sensitive and specific enzyme-linked immunosorbent assay (ELISA) utilizing recombinant chimeric borrelia proteins devoid of OspA (rNon-OspA) that can be used to detect antibodies to diagnostically important B. burgdorferi antigens in both OspA-vaccinated and nonvaccinated individuals. We tested sera from patients with Lyme disease and with conditions associated with false-positive serologies, OspA-vaccinated individuals, and healthy high-risk workers from an area of endemicity and normal sera from individuals from areas of nonendemicity. The rNon-OspA test was compared with two commercially available whole-cell immunoassays. The rNon-OspA assay is as sensitive and specific as the whole-cell assay (P > 0.05) for detection of anti-B. burgdorferi antibodies. However, the rNon-OspA assay can differentiate between populations comprised of naturally infected and OspA-vaccinated individuals (P < 0.05). Our data demonstrate that this new sensitive rNon-OspA ELISA can be used for the laboratory detection of B. burgdorferi antibodies regardless of vaccination status and could replace existing serologic assays for Lyme disease.

[Vector-borne diseases. Recent advances in the diagnosis, treatment and prevention]

Vector borne diseases are infections transmitted by arthropods. The vector can mechanically spread the infectious disease or give hospitality to microrganisms for their biological cycle. The etiologic agents of these infections are viruses as yellow fever and Dengue, protozoans as plasmodium of malaria, Leishmania spp., bacteria as Borrelia burgdorferi, Rickettsia spp. or worms as lymphatic filariasis. They are emerging infectious diseases for the epidemiological changes of our national territory (ex. Lyme disease) but especially for the significant increase of the imported forms. Malaria is the more important infection for its clinical management but also for its remote possibility of a further transmission in Italy. In this review are illustrated the recent progresses in the diagnosis, treatment and prevention of the main vector borne infections that the clinical physicians may frequently observe. It is very important to know these diseases because an adequate preparation and continuous updating are necessarily required.

Management of tick bites and early Lyme disease: a survey of Connecticut physicians

Practice guidelines have been published for the treatment of Lyme disease (LD). These guidelines have been challenged as inadequate. Two common LD management problems are antibiotic prophylaxis of deer tick bites (deer ticks may carry Borrelia burgdorferi, the spirochete that causes LD) and antibiotic treatment of erythema migrans, the pathognomonic rash of LD. A 1-page questionnaire was sent to a 13% (573/4300) sample of Connecticut physicians to define how they treat deer tick bites and erythema migrans. Questionnaires were returned by 320 (56%) of 573 physicians. Questionnaires were analyzed for the 267 physicians who saw patients with LD. Seventy (26%) of the 267 surveyed physicians prescribed antibiotic prophylaxis for patients with tick bites. B burgdorferi serology was ordered by 31% of physicians for patients with tick bites. Most surveyed physicians treated erythema migrans with doxycycline or amoxicillin for a mean of 21 days. Serology was ordered by 49% of physicians for patients with erythema migrans. Most physicians did not use prophylaxis for patients with deer tick bites. In addition, most of the physicians surveyed followed established guidelines for treating patients with erythema migrans. However, many of the physicians surveyed do serologic testing for patients with tick bites and/or erythema migrans. Serologic testing for these patients is usually not necessary.

Arthritis following recombinant outer surface protein A vaccination for Lyme disease

As more individuals receive outer surface protein A (OspA) vaccination, adverse effects not detected during phase III clinical trials may become apparent. Although arthritis has been described following other human vaccines, we found no reports of human cases after Lyme disease vaccination. We describe 4 males (2 children, 2 adults) who developed arthritis following recombinant OspA vaccination. The potential arthritogenic effect of OspA suggested by in vitro and animal studies finds a clinical correlate in these 4 cases.

Protection against tick-transmitted Lyme disease in dogs vaccinated with a multiantigenic vaccine

In an effort to develop a safe and effective vaccine for the prevention of Lyme borreliosis that addresses concerns raised over currently available vaccines, dogs were vaccinated twice with a multiantigenic preparation of Borrelia burgdorferi, strain N40, on days 0 and 20 of the experiment. About 70 and 154 days after the first immunization, dogs were challenged by exposing them to field-collected Ixodes scapularis ticks harboring B. burgdorferi. Vaccinated dogs were completely protected from infection by all criteria utilized to assess infection, developed high-titer anti-B. burgdorferi serum antibodies and growth inhibitory activity which persisted for over 200 days, and did not demonstrate any untoward consequence of vaccination. Serum absorption experiments revealed that borreliacidal and most likely protective antibodies in dogs receiving the multiantigenic preparation were not only elicited against the OspA antigen, but were also produced against additional yet to be determined targets on B. burgdorferi organisms. These data demonstrate that a multiantigenic vaccine is effective in preventing Lyme disease transmitted via the natural vector.

Asymptomatic Borrelia burgdorferi infection

Little is known about the natural history of asymptomatic Borrelia burgdorferi infection. Our analysis of the asymptomatic infections diagnosed serologically in a recent OspA vaccine trial conducted in the United States (N Engl J Med 1998;339: 209-215), suggests that the natural history of this event is more benign than that reported for untreated patients with erythema migrans (Ann Intern Med 1987;107: 725-731). We hypothesize that this is due either to incorrect diagnosis since the specificity of the serologic criteria used to diagnose asymptomatic infection in the vaccine study is unknown, or to infection with non-pathogenic strains of B. burgdorferi. Increasing evidence indicates that the invasive potential of strains of B. burgdorferi varies according to the specific subtype. Theoretically, a serologic testing method could be devised which would distinguish infection with invasive versus non-invasive strains of B. burgdorferi, and allow testing of the second hypothesis.