One summer evening a 63yearold white man came to the emergen

One summer evening, a 63-year-old white man came to the emergency department of a nearby hospital presenting with a 6-day history of fever, moderate headache, generalized myalgia, arthralgias, and fatigue. He had noticed a rash under the armpit that day that had spread rapidly, prompting him to seek medical attention. He had lived in Connecticut and had recently moved to a cottage in a wooded area outside of a small town. He noted multiple tick bites after his daily walks in the woods. He had otherwise maintained good health. His vital signs reported a temperature of 38.8 X, pulse 102/min, resting 14/min and blood pressure 134/82 mmHg. His physical exam noted an expanding erythematous skin lesion (erythemia migrans) under the axilla that had a central area of clearing (Figure 1). Laboratory studies showed normal blood gases and a normal differential with a white blood cell count of 7, 400/mu L. His hematocrit was 43% and his serum chemistries reported AST 156 U/L and ALT 189 U/L. No imaging studies were done. With what organism was he infected? What disease did he have? What in his history is suggestive of this disease? How is this disease transmitted? How, in the absence of a characteristic rash, is the diagnosis of this disease established? He was appropriately treated with antibiotics and did well. What complications can occur in patients with this disease, particularly those in whom there is no treatment or inadequate therapy? What efforts can be taken to prevent this illness?

Solution

1. The organism is infected with Lyme disease, also known as Lyme borreliosis. It is an infectious disease caused by bacteria of the Borrelia type.The most common sign of infection is an expanding area of redness, known as erythema migrans, that begins at the site of a tick bite about a week after it has occurred.

2. The most common sign of infection are:

Lyme disease is transmitted to humans by the bite of infected ticks of the Ixodes genus. Usually, the tick must be attached for 36 to 48 hours before the bacteria can spread.

3. Diagnosis of Lyme disease: