Lyme Disease Update Review
Information on lyme disease symptoms,sign,diagnosis,treatment and complication.This is an infectious disease caused by ticks infected with Borrelia burgdorferi.
Lyme Disease General Considerations
Lymedisease is a tick-borne illness caused by the spirochete B burgdorferi. Lymedisease can be divided into early disease (stage 1, EM), disseminated infection (stage 2), and late disease (stage 3, persistent infection). The first stage involves the skin, followed by stages 2 and 3, which often affect the skin, joints, CNS, and heart. However, any of the stages may fail to appear or may overlap with one another
Clinical stages of Lymedisease in children and adults
| Stage | Timing |
|---|---|
| Localized erythema chronicum migrans | Early infection |
| Disseminated infection | Within days or years |
| Persistent infection | Months to years |
Lyme Disease Epidemiology and Incidence
Lyme disease is the most common vector-borne infection in the United States. In 1997, there were 12,801 cases reported in the United States. It is transmitted by ticks from the genus Ixodes. The Ixodes tick goes through a 2-year life cycle that is composed of three stages: larva, nymph, and adult. Tick larvae acquire the spirochete via a blood meal from an infected host. Both the nymph and female adult infect humans.
A tick must be attached for at least 24 h to transmit the spirochete. Tick engorgement and attachment for 72 h are predictors of subsequent human infection. Ixodes ticks in the northeastern and midwestern United States belong to the Ixodes dammini (scapularis) species, in the western United States to Ixodes pacificus, in Europe to Ixodes ricinus, and in Asia to Ixodes persulcatus. Rodents and small mammals are the natural hosts of the larval and nymphal stages.
Overview of Lyme Disease
Lyme disease is a bacterial disease caused by Borrelia burgdorferi. The bacterium is transmitted to humans via a tick bite. Within 1 to 2 weeks after being infected, a “bull’s-eye” rash can develop at the tick bite site accompanied by fever, headache, and muscle or joint pain. Some people may have Lymedisease and not have any early symptoms. However, others can have a fever and other “flu-like” symptoms without a rash.
Cause of Lyme Disease
The primary vector of Lyme disease in the U.S. is the black-legged deer tick (Ixodes scapularis) . Other Ixodes ticks are also known to transmit the disease. Lyme disease is maintained in wild rodent populations, on which the larval and nymphal ticks develop. These immature ticks pick up the disease organism when they suck the blood of infected rodents. The nymphal and adult ticks then seek a larger host, such as deer or humans, to obtain their final blood meal and transmit the disease when they feed.
