Back To CourseMicrobiology: Help and Review
20 chapters | 336 lessons
As a member, you'll also get unlimited access to over 75,000 lessons in math, English, science, history, and more. Plus, get practice tests, quizzes, and personalized coaching to help you succeed.Try it risk-free
Angela has taught college Microbiology and has a doctoral degree in Microbiology.
Labor Day is fast approaching. It's a great time to pack up the family and head to the Adirondack Mountains for a final farewell to summer. After several hours of driving, you arrive at your cabin and decide to take a nature hike to stretch your legs before unpacking. You, your family, and your dog, Meatball, stroll off into the woods, but before long it opens into a beautiful field. The grass and goldenrod are waist-high, overgrowing the narrow deer trail. Your crew pushes through, brushing your bare legs through the grass. Every now and then you feel a tickle on your thighs, calves, and ankles but it is easily ignored in the glorious expanse of nature.
Later in the evening, you notice that every member of your party brought home hitchhikers: ticks. Those tickles were deer ticks finding a tantalizing blood vessel to settle into for a quick feed. Without worry, you pluck them all off and enjoy the rest of your vacation. Until those sinister bulls-eye-shaped rashes appear. Uh oh.
You, your family, and even Meatball, have just developed the first symptom of Lyme disease, an illness caused by the spirochete bacteria Borrelia burgdorferi, acquired by the bite of an infected deer tick, Ixodes scapularis. This bite from an infected tick is required for the development of Lyme disease. You should seek medical treatment, but you are busy and decide to ignore it. What you should expect now is three distinct stages of illness.
The first stage of Lyme disease occurs between 3 and 30 days after the tick bite. At the spot of the bite, a red rash develops and slowly expands, up to 12 inches across. The rash forms a classic bulls-eye shape, distinctive for Lyme disease. Erythema migrans is the name given to the red, bulls-eye shaped rash characteristic of Lyme disease. This rash is rarely itchy or painful, distinguishing it from a mosquito bite, and it appears in about 80% of those infected. In addition to the rash, you have probably developed a fever, swollen lymph nodes, muscle and joint aches, chills, and fatigue as your immune system starts mobilizing to attack the bacteria. This is the best, most effective time to start treatment. But, you didn't.
You're probably feeling pretty down with the initial flu-like symptoms, but things are about to get worse. Several days to several weeks after the rash appears, the bacteria begin spreading throughout your body via the bloodstream. Borrelia burgdorferi is an intracellular pathogen, meaning it can penetrate into your cells. The symptoms that develop now depend on what cells the bacteria invade. More rashes appear as the bacteria invade and destroy skin cells. Borrelia can migrate to your brain and spinal cord causing headaches, neck stiffness, and memory problems. Bacteria in your joints can lead to severely painful and swollen joints and shooting pains. In some cases, Lyme disease can lead to the onset of Bell's palsy, which is a loss of muscle tone in the face. One or both sides of your face can appear droopy, as you can no longer contract the facial muscles. Finally, Borrelia can invade your heart, destroying heart cells and changing your heart rhythm. This can cause heart palpitations and dizziness. I'm sure now you're feeling really sick all the time. By now, you really should have gotten treatment. But again, you didn't. Eventually, you feel better and chalk it all up to a case of the flu.
It has now been months to years after that tick bite on that memorable Labor Day vacation. Since then, you have suffered from occasional bouts of grossly swollen joints, usually your knees, accompanied by severe pain. You have numbness and tingling in your extremities and problems with your memory.
Eventually, you learn that all of these symptoms and their pattern are associated with Lyme disease. You think back to that tick bite and the red rash that followed. By now, you are probably very angry at yourself for not seeking medical attention from the get go. Maybe you could have avoided all this agony.
So, let's go back in time and do things a little differently. At the first appearance of the initial flu-like symptoms and bulls-eye rash, you went to your doctor. For the 80% of people that develop the classic bulls-eye rash, diagnosis of Lyme disease is a snap. Diagnosis is based on the appearance of the bulls-eye rash and a recent exposure to ticks. For the unfortunate 20% without the rash, diagnosis can be a bit trickier. Usually a patient has to test positive for Borrelia antibodies in two different blood tests. Testing negative in either test usually suggests that it is not Lyme disease. Unfortunately, false positive and false negative tests are common. This can lead to misdiagnosis, delayed treatment, and further development of symptoms.
Fortunately for you, you developed the rash and told your doctor about the tick bite. Early diagnosis and treatment with oral antibiotics is the most effective treatment for Lyme disease. Currently, the antibiotics of choice are doxycycline, amoxicillin, or cefuroxime axetil. If the illness has progressed to the heart or brain, intravenous antibiotics have been shown to be more effective.
Your course of doxycycline seems to have done the trick. So, why do you still feel sick? In about 10-20% of Lyme disease sufferers, treatment is not the end of the disease. Post-Treatment Lyme Disease Syndrome (or PTLDS) occurs when symptoms persist for months after treatment to eliminate the active Borrelia infection. In some severe cases, symptoms like fatigue, joint pain, and muscle aches can continue for years. Currently, no one has fully worked out why Lyme disease symptoms become chronic in some sufferers. One current theory is that the symptoms are a result of the damage done to the body and immune system during the active infection. Other scientists believe Borrelia causes an autoimmune disease in which the body's own immune system starts attacking its own cells. Regardless of why they occur, the symptoms usually improve with time, and the patient often recovers fully in several months. It is important to note that continued use of antibiotics has not proven to be effective at eliminating PTLDS because there is not an active Borrelia infection causing these symptoms.
Lyme disease is an illness caused by the spirochete bacteria Borrelia burgdorferi, acquired by the bite of an infected deer tick, Ixodes scapularis. The disease progresses in three distinct stages.
Three to thirty days after the tick bite, the infected person develops Erythema migrans which is the name given to the red, bulls-eye-shaped rash characteristic of Lyme disease. This is accompanied by fever, swollen lymph nodes, muscle and joint aches, chills, and fatigue.
Several days to weeks after the rash appears, the bacteria spread to the rest of the body via the bloodstream. Symptoms are dependent on the body system invaded and can include more skin rashes, headaches, neck stiffness, heart palpitations, dizziness, painful and swollen joints, and Bell's palsy, which is the loss of muscle tone in the face.
The final phase can last months to years and is characterized by grossly swollen knees, joint pain, numbness, tingling of the extremities, and memory problems.
Diagnosis often relies on the appearance of the classic bulls-eye rash and recent tick exposure. In the absence of a rash, two positive blood tests are required for a definitive diagnosis.
Treatment is best if started early and includes oral antibiotics. More severe cases can require intravenous antibiotics. Post-Treatment Lyme Disease Syndrome occurs when symptoms persist for months after treatment to eliminate the active Borrelia infection. Currently, there is no accepted reason for the chronic symptoms, but most people recover fully with time.
Following this lesson, you'll have the ability to:
To unlock this lesson you must be a Study.com Member.
Create your account
Already a member? Log InBack
Did you know… We have over 160 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.
To learn more, visit our Earning Credit Page
Not sure what college you want to attend yet? Study.com has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.
Back To CourseMicrobiology: Help and Review
20 chapters | 336 lessons