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A Single Dose of Doxycycline to Prevent Lyme Disease
The agent of Lyme disease is transmitted by the bite of Ixodes scapularis, but it is uncertain whether prophylactic antimicrobial treatment after a tick bite is an effective way to prevent Lyme disease. In this randomized, double-blind, placebo-controlled trial, half the subjects received a single 200-mg dose of doxycycline. Erythema migrans developed at the site of the tick bite in only 0.4 percent of those who received doxycycline, as compared with 3.2 percent of those who received placebo (P=0.04).
This large trial shows the efficacy, at least in a hyperendemic region, of a single, prophylactic dose of doxycycline to prevent Lyme disease. However, the infection rate was low even in the placebo group, and nausea and vomiting were common side effects with the treatment.
Related Editorial
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Prolonged Antibiotics for Chronic Lyme Disease
Some argue that prolonged antibiotic treatment can help patients who have persistent pain and fatigue despite previous treatment for acute Lyme disease. In randomized, double-blind trials, seropositive and seronegative patients received either intravenous ceftriaxone for a month plus oral doxycycline for two months or matching placebos. After an interim analysis, the trials were stopped. With a total of 115 patients able to be evaluated, there was no significant difference between the groups in the health-related quality of life six months after the treatment ended.
Although the small size of these two trials limits their power, the data indicate that there is little chance of any major benefit from prolonged antibiotic treatment for chronic Lyme disease. These studies document substantial impairment, but patients' symptoms improved or worsened regardless of whether they received antibiotic treatment.
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Neointimal and Tubulointerstitial Infiltration of Renal Allografts by Recipient Mesenchymal Cells during Chronic Rejection
Tissue remodeling is a prominent feature of chronic renal-allograft rejection. The investigators identified the source of the mesenchymal cells that participate in the remodeling process in male recipients of renal allografts from female donors by seeking the Y-chromosome body in biopsy specimens from the grafts. In six such cases, up to 38 percent of the mesenchymal cells contained a Y-chromosome body.
These data imply the existence of circulating mesenchymal cells that can colonize a renal allograft during chronic rejection and that participate in the response to injury in the graft.
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Neighborhood of Residence and Incidence of Coronary Heart Disease
Where a person lives may influence health-related behavior, such as smoking, eating, and exercising. This study examined the relation between characteristics of neighborhoods — such as the wealth, income, education, and occupation of residents — and the incidence of coronary heart disease. Analyses that controlled for established risk factors for coronary heart disease and the income, education, and occupation of individual residents showed that living in a disadvantaged neighborhood, independently of these other factors, was associated with an increased incidence of coronary heart disease.
These findings indicate that where a person lives may affect his or her health. Changing the neighborhood environment — for example, by increasing the availability of healthful foods or recreational facilities or by decreasing tobacco advertising — may help to promote better health.
Related Editorial
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High-Altitude Pulmonary Edema.
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Current Concepts: High-Altitude Illness
Each year, millions of people travel to high altitudes. Consequently, acute mountain sickness is a public health problem. This review explains how to recognize and treat patients with acute mountain sickness, high-altitude cerebral edema, and high-altitude pulmonary edema. Early diagnosis and prompt intervention are crucial. The authors also explain strategies for prevention.
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Medical Progress: Lyme Disease
Transmitted by the bite of an ixodes tick, infection with the spirochete Borrelia burgdorferi is now endemic in more than 15 states and has diverse clinical manifestations. A transient, expanding skin lesion (erythema migrans) may be followed by systemic involvement of the joints, nervous system, and heart. In addition to providing a detailed description of the clinical presentation and diagnostic methods, this article discusses aspects of antibiotic therapy and prevention.
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