Adjuvanted Lyme disease vaccine: a review of its use in the management of Lyme disease

[Lyme disease: basis for treatment strategy, primary preventive care and secondary preventive care]

Lyme disease is the most common tick borne disease and is caused by Borrelia burgdorferi sensu lato. Ticks of the genus Ixodes are the vectors that transmit the infection to host mammals in endemic foci. Ixodes is infected by Borrelia at larval stage when it feeds on infected mammals. Man is an occasional host. The infection risk is linked to interaction between human and the natural environment. Strategies for prevention are closely related to the enzootic cycle of the Ixodes tick. Environmental measures to reduced tick density or host mammals are expensive, need to be repeated annually and cannot be applied to large areas. The primary prevention could be reduced to personal preventive measures such as reducing the amount of exposed skin and frequent checking for ticks. The risk of Lyme disease transmission after a tick bite is relatively low, and remains under 4%. The transmission rate depends on the duration of feeding. A rapide tick removal with fine tweezers or preferably special forceps and disinfection of the bite site appear to be the best technique. The absence of scientific evidence, and the risk of adverse events does not lead to recommending antimicrobial prophylaxis. Follow-up and educating the patients on the disease, clinical manifestation, and later primary prevention should be undertaken.

Tick-borne encephalopathies : epidemiology, diagnosis, treatment and prevention

Tick-borne encephalopathies constitute a broad range of infectious diseases affecting the brain and other parts of the CNS. The causative agents are both viral and bacterial. This review focuses on the current most important tick-borne human diseases: tick-borne encephalitis (TBE; including Powassan encephalitis) and Lyme borreliosis. Rocky Mountain spotted fever (RMSF) and Colorado tick fever (CTF), less common tick-borne diseases associated with encephalopathy, are also discussed. TBE is the most important flaviviral infection of the CNS in Europe and Russia, with 10 000-12 000 people diagnosed annually. The lethality of TBE in Europe is 0.5% and a post-encephalitic syndrome is seen in over 40% of affected patients, often producing a pronounced impairment in quality of life. There is no specific treatment for TBE. Two vaccines are available to prevent infection. Although these have a good protection rate and good efficacy, there are few data on long-term immunity. Lyme borreliosis is the most prevalent tick-borne disease in Europe and North America, with >50 000 cases annually. Localised early disease can be treated with oral phenoxymethylpenicillin (penicillin V), doxycycline or amoxicillin. The later manifestations of meningitis, arthritis or acrodermatitis can be treated with oral doxycycline, oral amoxicillin or intravenous ceftriaxone; intravenous benzylpenicillin (penicillin G) or cefotaxime can be used as alternatives. The current use of vaccines against Lyme borreliosis in North America is under discussion, as the LYMErix vaccine has been withdrawn from the market because of possible adverse effects, for example, arthritis. RMSF and CTF appear only in North America. RMSF is an important rickettsial disease and is effectively treated with doxycycline. There is no treatment or preventative measure available for CTF.

[Lyme disease--new findings on its physiopathology, diagnosis, therapy and prevention]

INTRODUCTION

Lyme disease is a tick-borne disease caused by a spirochete Borrelia burgdorferi, which manifests as a multisystem disease of the skin, nervous system, heart and joints. Recently it is the most common vector-borne disease in Yugoslavia.

NEW EPIDEMIOLOGICAL STUDIES

New epidemiological studies revealed that ticks can occasionally be infected not only by Borrelia burgdorferi, but also by some other microbes that can cause diseases in humans. Recently discovered the variable major protein-like sequence, antigenic variation of B. burgdorferi B 31 partly explains the ability of this organism to evade an active immune response. A key role in development of clinical symptoms associated with lyme disease belongs to the connection with ability of B. burgdorferi to induce and activate metallopeptidases and fibrinolytic enzymes, leading to extracellular matrix destruction.

DIAGNOSIS AND TREATMENT

Diagnosis of Lyme borreliosis is made on the basis of clinical picture, exposure to ticks in endemic areas and serologic confirmation. It seems that polymerase chain reaction has little role in detection of B. burgdorferi in urine, blood, and spinal fluid samples, but it is most useful in evaluating the effectiveness of antibiotic therapy of Lyme arthritis. Infectious Diseases Society of America had prepared new guidelines for selective treatment of Lyme disease. Vaccination is still the best way of prevention for people living in high-risk areas.

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.

Lyme disease in children

Lyme borreliosis is a multisystem disorder caused by Borrelia burgdorferi and transmitted by ticks in the northern hemisphere. The disease is common in children. In addition to frequently recognized manifestations such as erythema migrans, neuroborreliosis, and Lyme arthritis, rarer manifestations, including eye and ear disease, are increasingly understood. Clinical diagnosis is supported by serologic confirmation. Improvement of laboratory methodology, especially polymerase chain reaction-based tests, is continuing. Actual treatment recommendations based on controlled studies reflect expanding scientific knowledge. In the United States, license of a vaccine to prevent infection in children is awaited. Lyme borreliosis is an intriguing human example of bacterial persistence in the presence of the host immune system. Chronic Lyme arthritis is a model of chronic arthritis resembling forms of arthritis of unknown cause, such as rheumatoid arthritis and juvenile idiopathic arthritis.

Lyme disease

Lyme disease is the most common tick-borne disease in the United States, and the number of reported cases has increased steadily since 1992. Coinfection of ticks with Borrelia burgdorferi and Ehrlichia phagocytophila did not appear to affect the transmission of the other agent. Serologic evidence of exposure to Babesia microti did not significantly impact the clinical course of Lyme disease. Two clinical studies indicated that the long-term outcome of Lyme disease is good. Results are pending of chronic Lyme disease studies funded by the US National Institutes of Health. A better understanding of the pathogenesis of Lyme disease provided clues about possible mechanisms for persistent symptoms. Use of the current method of diagnosis by the two-step approach has proven to be reliable, but new methods are under investigation. Treatment guidelines were published recently. OspA vaccination of children aged 2 to 5 years was shown to be safe and immunogenic.