The causative agent for Lyme Borreliosis which is also simply known as Lyme disease is a bacterium called Borrelia burgdorferi. This is the bacterium that causes the disease in United States but in Europe another form of bacterium is known to cause the same disease and this is known as Borrelia afzelii (Nitch, 2007). This bacterium is usually found in the intestinal tracts of squirrels, mice and other small animals. This is their natural habitat and they are transmitted to human beings through bites by a certain group of ticks.
The ticks involved in transmission of this disease depend on the geography. For example in north central and northeastern part of U. S. the disease is transmitted by the black-legged tick which is also known as the deer tick but around the U. S. pacific coastal region, the tick involved is known as western black legged tick (Nitch, 2007). There are several characteristics associated with this bacterium. One of these is that this bacterium is a spirochete thus it appears like a tightly coiled spring.
This bacterium moves by help of an endoflagella and its length is larger than its width (Todar, 2008). When a gram stain is done, the bacterium appears like a weak gram negative but this is usually by default meaning it appears so just because the last stain to be applies is usually reddish and so it takes this stain (Lipsker & Jaulhac, 2009). Generally, this bacterium is not grouped as gram negative or gram positive. Another feature of its morphology is that it has both outer and inner membranes.
Between these two membranes is a perisplasmic space which is composed of peptidoglycan and this means that the bacterium has a cell covering that is characteristic of gram negative cells even though it does not behave like a gram negative microbe in terms of staining (Todar, 2008). Another thing is that their outer membrane is made up of unique surface proteins whose function is to enhance its virulence (Todar, 2008). This microbe is related to other microbes in several ways. To begin with, it causes symptoms similar to those caused by other organisms such as arthritis and headaches.
Another thing is that the disease is transmitted to the human host through a vector just like some diseases. In addition, the microbe undergoes a life cycle where it alternates between animal, human host, and the environment and this also happens with some microbes. It is similar to Treponema pallidum in that both are spirochetes This organism does not meet all the requirements needed for an organism to pass Koch’s postulates test. To begin with, the disease is caused by pathogens that are not similar.
There are three genospecies of Borrelia that are isolated from people with Lyme disease and these include Borrelia afzelii, Borrelia burgdorferi, and Borrelia garinii (Todar, 2008). On the other hand, the bacterium meets the requirements in that the bacteria can be grown in pure culture after isolation from a human being. Research has shown that after the bacteria have grown, they can be injected into mice which become infected and analysis of a blood sample from such mice shows the original species (Lipsker & Jaulhac, 2009). The signs and symptoms of this disease change as the disease progresses.
This is because with time different body organs become affected by the bacterium. Depending on an individual, some or all of the known symptoms that are associated with this disease may be exhibited (Centers for Disease Control [CDC], 2008). The first sign of the disease is observed at the point where the tick bit the skin and this is usually the point through which the bacteria got into the body. At this point, the sign observed is a circular reddish rash which is known as erythema migrans. Medically, Lyme disease can be classified into three phases.
The first phase is known as the early phase where the disease is localized (American Lyme Disease Foundation [ALDF], 2010). The first sign of this phase is the circular rash. This occurs in about 70-80% of all the infected individuals and the time it takes to appear ranges from 3-30 days since the tick bite (CDC, 2008). This rash expands gradually in a circular manner and can become as large as 30cm in diameter (CDC, 2008). At times this circular appears as a bright red outer ring and a central area of redness with a clearing between the outer ring and the inner solid part. This appearance is known as the bull’s eye appearance (see figure 1).