solve the CHAPTER MYSTERY

THE SEARCH FOR A CAUSE

The disease of unknown cause was named Lyme disease, after the town of Lyme, Connecticut, where many of the patients lived. Steere's investigation was helped by a researcher who isolated a bacterium called Borrelia burgdorferi from deer ticks. The ticks had been captured in the area where patients lived. Steere found the same bacterium in the patients. Could this bacterium be the cause of Lyme disease?

For ethical reasons, Steere could not infect healthy people with the bacterium, but he did infect healthy laboratory mice. The mice developed arthritis and other symptoms that were similar to the Lyme disease patients' symptoms. Steere recovered bacteria from sick mice and injected them into healthy mice, which then also developed the disease.

Now researchers know that a bite from a deer tick carrying B. burgdorferi may transmit the bacterium. B. burgdorferi can “swim” through tissues around tick bites, causing the spreading rash that some patients reported. The bacterium then seems to infect many types of cells, including macrophages, nerve cells, and muscle cells. Some B. burgdorferi proteins resemble proteins in the myelin sheaths around some nerve cells. This may cause an autoimmune response that leads to arthritis and other problems that persist after the infection is gone.

1. Explain What set of rules did Steere use to determine if B. burgdorferi was the pathogen responsible for Lyme disease?

2. Infer Lyme disease patients who are quickly treated with antibiotics usually do much better than those who are treated later. Why do you think this is the case?

3. Connect to the Deer and deer ticks thrive in wooded areas that grow back after the areas have been cleared and at the edges of woodlands. How might suburban development contribute to an increase in Lyme disease?