Borrelia

CASE 1

• After a severe drought in the Sahel region of SubSahara Africa, waves of migrants have crossed the border into Northern Ghana. In one make-shift village, Malian refugees are suffering from a recurring febrile illness that is not responsive to treatment with antimalarials. One typical patient is a 52 year old woman who is experiencing her fourth episode of fever. Her illness began with a fever, shaking chills, muscle aches, and headache that lasted for 5 days and then resolved after taking an antimalarial medication. However, after a 10-day fever-free period, the same symptoms reoccurred. This time, the fever resolved after two days, before the patient was given any antimalarial drug. Another 10 days passed, and the fever recurred for 2 days and again resolved spontaneously. The most recent fever again recurred ~10 days after the provious one.

• On physical examination, the temperature was 38.6 degrees. there was modest enlargement of the liver and spleen. There was no rash, but the there were numerous scratches.

• A complete blood count was performed and showed only mild anemia. However, the technician who examined the blood smear noted some unusual, coiled structures on the smear (blue arrows)

• The patient was treated with a single dose of tetracycline (500mg), and her fever recurrences stopped.

Questions:

1. How was this infection acquired? Which two arthropods can trasmit this disease? Which do you think was the more likely vector in this case?
2. Why did the fever recur? What bacterial genetic phenomenon is responsible for the "relapsing" nature of Relapsing Fever? How does this phenomenon benefit the bacteria?
3. Why is this bacterium shaped as it is? What accounts for its shaped?

CASE 2

• In May, a 12 year old boy who lives on the East Coast of the United States is brought to the clinic because of an enlarging rash on his left shoulder. The rash is painless and does not itch. It began as a small red circle that has gradually expanded over the past week while resolving in the center, to given the impression of an enlarging ring.

• The boy is up to date on all of his immunizations. He has no underlying diseases and is taking no medications. He participates on the cross-country running team at his junior secondary school, and he is a member of the Boy Scouts. He has no history of a tick bite.

• His examination is unremarkable except for the presence of the rash shown below:

• No laboratory tests are ordered, but the boy is treated with a 2-week course of amoxicillin for Lyme disease. the rash resolves, and he has no further problems.

Questions:

1. Why was no attempt made to confirm this diagnosis?
2. To what does the arrow in photograph above point?
3. Are you surpised that the boy has no history of a tick bite?
4. If this infection was transmitted by a tick bite, how did the tick become infected?
5. If there were an effective, widely-used vaccine against this disease that prevented people from becoming infected, could Lyme disease be eradicated?
6. If this boy had not come to the clinic and been treated, what clinical consequences may have developed over the next several months? Over the next several years?
7. Which common complication of Lyme disease does this girl demonstrate?



8. If a patient never noticed the rash, a presented to the physician with one of these late complications, how would the diagnosis of Lyme disease be made?
9. How does the disease in America differ from the disease in Europe?