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Definition of Lyme Borreliosis
Lyme disease, or Lyme borreliosis, is an emerging infectious disease caused by at least three species of bacteria belonging to the genus Borrelia. Borrelia burgdorferi sensu stricto is the main cause of Lyme disease in the United States, whereas Borrelia afzelii and Borrelia garinii cause most European cases. The disease is named after the town of Lyme, Connecticut, USA, where a number of cases were identified in 1975. Although Allen Steere realized that Lyme disease was a tick-borne disease in 1978, the cause of the disease remained a mystery until 1981, when B. burgdorferi was identified by Willy Burgdorfer.
Symptoms of Lyme Borreliosis
Lyme disease can affect multiple body systems and produce a range of symptoms. Not all patients with Lyme disease will have all symptoms, and many of the symptoms are not specific to Lyme disease, but can occur with other diseases as well. The incubation period from infection to the onset of symptoms is usually one to two weeks, but can be much shorter (days), or much longer (months to years). Symptoms most often occur from May through September, because the nymphal stage of the tick is responsible for most cases. Asymptomatic infection exists, but occurs in less than 7% of infected individuals in the United States. Asymptomatic infection may be much more common among those infected in Europe.
Causes of Lyme Borreliosis
Lyme disease is caused by Gram-negative, spirochetal bacteria from the genus Borrelia. The Borrelia species that are Lyme-related are collectively known as Borrelia burgdorferi sensu lato, and show a great deal of genetic diversity. Borrelia burgdorferi sensu lato is made up of 18 closely related species, but only three clearly cause Lyme disease: B. burgdorferi sensu stricto (predominant in North America, but also present in Europe), B. afzelii, and B. garinii (both predominant in Eurasia). Some studies have also proposed B. bissettii and B. valaisiana may sometimes infect humans, but these species do not seem to be important causes of disease.
Diagnosis of Lyme Borreliosis
Lyme disease is diagnosed clinically based on symptoms, objective physical findings (such as erythema migrans, facial palsy or arthritis) or a history of possible exposure to infected ticks, as well as serological blood tests. The EM rash is not always a bullseye, i.e., it can be red all the way across. When making a diagnosis of Lyme disease, health care providers should consider other diseases that may cause similar illness. Not all patients infected with
Lyme disease will develop the characteristic bullseye rash, and many may not recall a tick bite.
Diagnosis of late-stage Lyme disease is often complicated by a multifaceted appearance and nonspecific symptoms, prompting one reviewer to call Lyme the new "great imitator." Lyme disease may be misdiagnosed as multiple sclerosis, rheumatoid arthritis, fibromyalgia, chronic fatigue syndrome, lupus, Crohn's disease or other autoimmune and neurodegenerative diseases.
Treatment of Lyme Borreliosis
Antibiotics are the primary treatment for Lyme disease; the most appropriate antibiotic treatment depends upon the patient and the stage of the disease. According to the Infectious Diseases Society of America (IDSA) guidelines, the antibiotics of choice are doxycycline (in adults), amoxicillin (in children), erythromycin (for pregnant women) and ceftriaxone, with treatment lasting 10 to 28 days. Alternative choices are cefuroxime and cefotaxime. Treatment of pregnant women is similar, but doxycycline should not be used.
A double blind, randomized, placebo-controlled multicenter clinical study indicated three weeks of treatment with intravenous ceftriaxone, followed by 100 days of treatment with oral amoxicillin did not improve symptoms any more than just three weeks of treatment with ceftriaxone. The researchers noted the outcome should not be evaluated after the initial antibiotic treatment, but rather 6–12 months afterwards. In patients with chronic posttreatment symptoms, persistent positive levels of antibodies did not seem to provide any useful information for further care of the patient.
In later stages, the bacteria disseminate throughout the body and may cross the blood-brain barrier, making the infection more difficult to treat. Late diagnosed Lyme is treated with oral or intravenous antibiotics, frequently ceftriaxone for a minimum of four weeks. Minocycline is also indicated for neuroborreliosis for its ability to cross the blood-brain barrier.
Prognosis of Lyme Borreliosis
For early cases, prompt treatment is usually curative. However, the severity and treatment of Lyme disease may be complicated due to late diagnosis, failure of antibiotic treatment, and simultaneous infection with other tick-borne diseases (coinfections), including ehrlichiosis, babesiosis, and immune suppression in the patient.
A meta-analysis published in 2005 found some patients with Lyme disease have fatigue, joint or muscle pain, and neurocognitive symptoms persisting for years, despite antibiotic treatment. Patients with late stage Lyme disease have been shown to experience a level of physical disability equivalent to that seen in congestive heart failure. In dogs, a serious long-term prognosis may result in glomerular disease, which is a category of kidney damage that may cause chronic kidney disease. Dogs may also experience chronic joint disease if the disease is left untreated. However, the majority of cases of Lyme disease in dogs result in a complete recovery with, and sometimes without, treatment with antibiotics. In rare cases, Lyme disease can be fatal to both humans and dogs.
Prevention of Lyme Borreliosis
Protective clothing includes a hat, long-sleeved shirts and long trousers tucked into socks or boots. Light-colored clothing makes the tick more easily visible before it attaches itself. People should use special care in handling and allowing outdoor pets inside homes because they can bring ticks into the house.
Attached ticks should be removed promptly, as removal within 36 hours can reduce transmission rates. One study concluded that a single dose of doxycycline given within 72 hours after a high-risk tick exposure can prevent the development of Lyme disease.
A community can prevent Lyme disease by reducing the numbers of primary hosts on which the deer tick depends, such as rodents, other small mammals, and deer. Reduction of the deer population may, over time, help break the reproductive cycle of the deer ticks and their ability to flourish in suburban and rural areas.
An unusual, organic approach to control of ticks and prevention of Lyme disease involves the use of domesticated guineafowl. Guineafowl are voracious consumers of insects and arachnids, and have a particular fondness for ticks. Localized use of domesticated guineafowl may reduce dependence on chemical pest-control methods.
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