Lyme disease

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Lyme disease
Maturski, seminarski i diplomski radovi iz biologije i ekologije.

Lyme disease is a bacterial infection transmitted by tick bites. There are a variety of symptoms of Lyme disease including a skin rash around the tick bite and various later general symptoms such as fever, fatigue and many other possible symptoms. Lyme disease is difficult to diagnose, especially if the characteristic skin rash around the tick bite is absent. Lyme disease is one of a group of conditions with vague symptoms such as fatigue, aches, or malaise. In mild cases, people may not even seek medical advice unless symptoms become more severe The disease is named after the village of Lyme, Connecticut where a number of cases were identified in 1975. Although Allen Steere realized in 1978 that Lyme disease was a tick-borne disease, the cause of the disease remained a mystery until 1982, when B. burgdorferi was identified by Willy Burgdorfer.

Biology of the Pathogen

Lyme disease is caused by Gram-negative spirochetal bacteria from the genus Borrelia. At least 11 Borrelia species have been discovered, 3 of which are known to be Lyme-related.1 The Borrelia species that cause Lyme disease are collectively known as Borrelia burgdorferi sensu lato, and show a great deal of genetic diversity. Single photon emission computed tomography (SPECT) imaging has been used to look for cerebral hypoperfusion indicative of Lyme encephalitis in the patient. Although SPECT is not a diagnostic tool itself, it may be a useful method of determining brain function.

Life cycle

The group Borrelia burgdorferi sensu lato is made up of three closely-related species that are probably responsible for the large majority of cases: B. burgdorferi sensu stricto (predominant in North America, but also present in Europe), B. afzelii, and B. garinii (both predominant in Eurasia). 2Patients with late stage Lyme disease have been shown to experience a level of physical disability equivalent to that seen in congestive heart failure. In rare cases, Lyme disease can be fatal. Hard-bodied ticks of the genus Ixodes are the main vectors of Lyme disease.Most infections are caused by ticks in the nymphal stage, as they are very small and may feed for long periods of time undetected.3

Biology of the host

A specific species of bacteria, part of the Borrelia Burgdoreferi group, whose common name is Lyme disease spirochete. Lyme disease can spread throughout the body during the course of the disease and has been found in the skin, heart, joint, peripheral nervous system, and central nervous system. Lyme disease in sub-Saharan is presently unknown, but evidence indicates that Lyme disease may occur in humans in this region. The abundance of hosts and tick vectors would favor the establishment of Lyme infection in Africa.4 Lyme disease can affect multiple body systems and produce a range of symptoms. Lyme disease has been reported in 49 of 50 states in the U.S, about 99% of all reported cases are confined to just five geographic areas (New England, Mid-Atlantic, East-North Central, South Atlantic, and West North-Central).
Lyme disease are susceptible to false-positive results from poor laboratory technique. Antibiotics are the primary treatment for Lyme disease; the most appropriate antibiotic treatment depends upon the patient and the stage of the disease.5

Common bullseye rash pattern associated with Lyme disease

Ecology and evolution

As a consequence of increased human contact with host and vector, the likelihood of transmission of the disease has greatly increased. Human expansion has also resulted in reduction of predators that hunt deer as well as mice, chipmunks and other small rodents – the primary reservoirs for Lyme disease. As a consequence of increased human contact with host and vector, the likelihood of transmission of the disease has greatly increased.6 Researchers are investigating possible links between global warming and the spread of vector-borne diseases, including Lyme disease. Many of the signs and symptoms of Lyme disease are a consequence of the immune response to the spirochete in those tissues. Adult ticks may also transmit disease to humans. After feeding, female adult ticks lay their eggs on the ground, and the cycle is complete. On the West Coast of the United States, Lyme disease is spread by the western black-legged tick (Ixodes pacificus), which has a different life cycle.

History of the disease and why we care

Lyme disease is not new. The skin rash of Lyme disease was first described by A fzelius in Sweden in 1909. Here in Connecticut, the Lyme disease story began in 1975 when unusual arthritis cases were reported from the towns of Lyme and Old Lyme. That year Dr. Allen Steere and his group at Yale went on to identify 51 c ases of Lyme arthritis in the Lyme area. In 1977, researchers discovered that t he deer tick Ixodes dammini transmitted the disease. In 1982, Dr. Burdorfer dis covered that the disease was caused by a newly recognized spirochete now known a s Borrelia burdorferi. In 1982, the first Lyme disease brochure was developed by the Connecticut Chapte r of the Arthritis Foundation. In 1984, the blood test for Lyme disease became sidely available in Connecticut. Lyme disease became a reportable disease in Co nnecticut in July 1987. Extensive national media coverage of Lyme disease began in the summer of 1988 with ABC’s 20/20 story. The early European studies of what is now known as Lyme disease described its skin manifestations. The first study dates to 1883 in Wrocław, Poland (then known as Breslau, Free State of Prussia) where physician Alfred Buchwald described a man who had suffered for 16 years with a degenerative skin disorder now known as acrodermatitis chronica atrophicans. The biliary system gives us a chance to trap the toxins while they are in the gut. Substances that trap fat-soluble compounds can be taken orally to do this. Care must be taken not to use these chronically because they can have side effects and reduce the absorption of healthy fat soluble vitamins and nutrients. Continued research is essential for further progress against Lyme disease. More work is needed to improve diagnostic tests, to understand why some patients’ symptoms disappear while other patients’ symptoms persist, to develop a vaccine for children, and to improve treatment for people with chronic Lyme disease.

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04-05-2010 10:48 PM
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