Relationship with Humans

B. burgdorferi has a highly relevant connection with humans. It is well-known for causing the most common vector-borne bacterial disease in the world, 

with over 20 000 infections per year: the Lyme disease.

Fig.22. A Sign Warning of
the Presence of Ticks

Lyme disease is the most common in areas where the transmitter of the disease, the Ixodes ticks are found in: 

wooded ares in the northern hemisphere.

Humans are secondary hosts of B. burgdorferi.

The only way humans can be infected by B. burgdorferi is when a carrier of this pathogen accidentally attach to and bite humans, while searching for other mammals, such as a deer.

Fortunately, transmission from human to human is unknown, not even during pregnancy or through breast milk: Lyme disease is not contagious.

Fig.23. A Tick Attached
to Human Skin

In order for B. burgdorferi to be transmitted, the ticks need to be attached to the host skin for 24 to 48 hours, with the success of the transmission increasing with the tick attachment duration.

Lyme disease can be divided into three distinct stages.

Symptoms:

Fig.24. An Erythema Migran

Stage I: Erythema chronicum migrans (a circular red rash at the site of the tick bite, resembling a bull’s eye) and flu-like symptoms: fatigue, fever,headache, muscle and joint aches, and malaise,  a feeling of “discomfort or uneasiness”.

If the symptoms are not recognized and the infection is left untreated, the disease moves on to its second stage.

Stage II: facial palsy (or paralysis), meningitis (inflammation of the protective membranes of the brain and spinal cord), extreme joint and muscle pain, and palpitation (abnormality in heartbeat)

After several months of disregard, the Stage III beings.

Stage III: arthritis (a type of joint disorder) accompanied by severe joint pain and swelling, vision problems

Treatment:

A vaccine for human use is currently unavailable. 

Fig.25, Treatment for Lyme Disease
Involves Taking Antibiotics.

However, in the early stage of this disease, a few-weeks-long treatment involving antibiotics like amoxicillin or doxycycline is available.

In the late stages of this disease, treatment usually takes months of various antibiotics and other drugs. Being a Gram-negative bacterium with an impenetrable wall, it is highly resistant to antibodies and antibiotics.

Therefore it is crucial for early diagnosis and subsequent treatment.

Diagnosis:

Tick bites are usually painless, and symptoms of Lyme disease during its early stages of Lyme are easily mistaken for typical flus or rashes; therefore, it isn't uncommon for Lyme disease to be left untreated for months before people become suspicious of an infection. 

Diagnosis of this infection is done through a blood test. 

The presence of antibodies will indicate that the body has been infected by B. burgdorferi. Antibodies are proteins created by the body’s immune system to fight foreign substances.

Fig.26. Watch Out for
InfectiousTicks!

Prevention:

The best way to prevent Lyme disease is to protect the body from Ixodid ticks, by minimizing skin exposure when in wooded or grassy areas, which is where the ticks are the most commonly found.

Currently, scientists are trying to figure out the pathogenesis of B. burgdorferi, the mechanism that causes the Lyme disease. 

However, due to its specific nutritional requirements, 

the bacterium is difficult to culture in vitro.