Lyme Disease - Introduction & Disease Transmission

Introduction & Disease Transmission

		LYME DISEASE was recognized in Sweden as long ago as 1908. It was first identified in the United States in 1975, after a mysterious outbreak of arthritis among the residents of Lyme, Connecticut. Since then, reports of Lyme disease have increased dramatically, and the disease has become an important public health problem in some areas of the United States. Lyme disease is an infection caused by Borrelia burgdorferi, a member of the family of corkscrew-shaped bacteria known as spirochetes and is transmitted by ticks.

DISEASE TRANSMISSION

Ticks infected with Borrelia burgdorferi transmit Lyme disease. In the Northeast, the tick most commonly associated with the disease is the blacklegged tick, Ixodes scapularis. Some closely related ticks (i.e. Ixodes pacificus and I. ricinus) have been identified as transmitting the disease in other parts of the United States and the world.


Ixodes scapularis		B. burgdorferi

The larval and nymphal stages of the tick are no bigger than a pinhead (less than 2 mm). Adult ticks are only slightly larger. Research in the eastern United States has indicated that, generally, ticks transmit Lyme disease to humans during the nymphal stage, probably because nymphs are rarely noticed on a person’s body due to their small size. Thus, the nymphs typically have ample time to feed and transmit the infection (ticks need at least 24 to 36 hours to transmit the infection).


Ixodes scapularis		Engorged female tick

Ticks search for host animals from the tips of grasses and shrubs and transfer to animals or persons who brush against vegetation. They usually attach themselves in areas that are more hidden or hairy, such as the groin, armpits, and scalp. However, ticks can attach under watch bands and waistbands, and in many other body locations. Ticks feed on blood by inserting their mouthparts into the skin of a host animal. They are slow feeders: a complete blood meal can take 3 to 5 days.

Although in theory Lyme disease could spread through blood transfusions or other contact with infected blood or urine, no such transmission has been documented. There is no evidence that a person can get Lyme disease from the air, food or water, from sexual contact or directly from wild or domestic animals. There is no convincing evidence that insects such as mosquitoes, flies, or fleas can transmit Lyme disease.

Lyme Disease Website Directory
Introduction & Disease Transmission | Epidemiology | Life Cycle of Blacklegged Tick
Symptoms, Diagnosis & Treatment
Lyme Disease & Dogs | Disease Prevention

Site Administrator
Updated 9/11/2001