Lyme Disease

Introduction

Lyme disease is caused by spirochete Borrelia burgdorferi named after the researcher who identified the bacteria in 1977. B. burgdorferi is a tick-borne parasite whose normal reservoir is a variety of small mammals such as rodents in which it does not lead to disease. In humans, however, it causes Lyme disease as the results of the immuno-pathological responses. It can also cause disease in dogs often leading to limbs paralysis. 

Epidemiology

We are in the middle of an epidemic of Lyme disease in Pennsylvania and surrounding states. B. burgdorferi is transmitted by a deer tick, but not only deer are the culprits that bring the ticks to our yards. Very often are rodents and squirrels or other wild animals. The ticks fall off the animals and reside in the grass or fallen leaves where they come in contact with humans.
 
Only a small fraction of female ticks carry disease. The longer the infected tick is attached to the skin, the higher is the risk of acquiring Lyme disease.
 
Children are at much higher risk of infection than adults.

Disease

Infection with B. burgdorferi occurs after a tick bite that is infected with the spirochete. Bacteria then migrate through the blood and connective tissue spreading through the system. Common manifestation is skin rash called erythema migrans and may appear anywhere in the body often causing characteristic pattern called “bull eye”. In later stages, Lyme disease affects the nervous system, joints, and heart.  

Lyme disease usually causes low grade fever, skin rashes, malaise, headaches, arthritis and all types of neurologic symptoms. 

Chronic Lyme disease can lead to significant disability and sometimes severe neurologic diseases including multiple sclerosis (MS). For that reason, Lyme disease should be treated very aggressively from the very beginning.

Diagnosis

Diagnosis is usually based on a blood test which is far from perfect so negative blood test does not rule out the presence of Lyme disease. The appearance of characteristic rash and history of tick bite should however be sufficient to initiate therapy with antibiotics before that test result is available.

Treatment

The treatment of Lyme disease involves administration of antibiotic for at least a month in acute phase. The earlier the treatment is started the better are the outcomes. The spirochete are very sensitive to antibiotics and acute infection can be easily controlled. 

In later stages, however, the treatment of Lyme disease becomes a challenge. The spirochetes have the ability to create “bio-films” not penetrable by antibiotics which leads to relapses of infection. Additionally, spirochetes often escape our immune system because of antigenic variation. 

In the chronic stage, administration of antibiotics only would not be sufficient. The treatment should include strengthening of the immune system, control of inflammation, treatment of neurological sequelae etc.

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