Medical Surveillance Monthly Report. Volume 16, Number 7, July 2009
Abstract
Lyme disease is a zoonotic tick-borne disease that is caused by infection with a spirochetal bacterium of the genus Borrelia. It has a worldwide distribution and is endemic in many temperate regions of the northern hemisphere. In the United States, it is hyperendemic along the mid- and northeastern Atlantic seaboard and in nonurban areas of Wisconsin. Lyme disease is transmitted by ticks that feed on both humans and animal hosts of Borrelia (e.g., deer, mice, raccoons). Borrelia are usually transmitted to humans during blood meals of ticks in the nymphal stages of their life cycle. Nymphal stage ticks are very small (approximately the size of poppyseeds); hence, they often feed undetected for the time required to transmit infection (24-48 hours). In the United States, the "deer tick" (Ixodes scapularis) and western blacklegged tick (Ixodes pacificus) are competent vectors of Lyme disease. The clinical manifestations and courses of Lyme disease are highly variable. The time from infection to initial symptoms is generally 7-14 days (range: 3 to >30 days). The presenting manifestation of Lyme disease is often a slowly enlarging, centrally clearing ("bull's-eye") rash at the site of the infecting tick bite (erythema migrans). While erythema migrans is a distinctive characteristic of Lyme disease, it occurs in only 60-80% of cases. Other early manifestations are non-specific and include fever, headache, muscle aches, joint pains, lymphadenopathy, malaise, and fatigue. Without effective antibiotic treatment, acute symptoms can persist for weeks or more. Weeks to months after infection, clinical manifestations of inflammation of the joints, nervous system (e.g., facial palsy, encephalitis), and heart (e.g. conduction abnormalities) can occur. Most cases are effectively treated with single courses of antibiotics.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 2009
- Accession Number
- ADA506214
Entities
Organizations
- Armed Forces Health Surveillance Center