The causative agent of Lyme disease is the bacterium Borrelia burgdorferi and is transmitted by the bite of infected ticks. In the east coast of the United States the tick vector is Ixodes scapularis, whereas in the Pacific coast Ixodes pacificus vectors the disease.
Infected ticks must feed on the host for 36-48 hours to transmit the bacterium. This is not uncommon since nymphs which are less than 2mm are hard to see and are active during the spring and early summer. Adult ticks can also transmit Lyme disease but they are easier to spot and do not became active until the fall.
Lyme disease is a tick-borne disease. Thus, there are no other natural routes for transmission.
- Lyme disease cannot be transmitted by direct contact from person to person.
- There are some reports that suggest that Lyme disease acquired during pregnancy lead to the infection of the placenta but its relation with stillbirth is unlikely. Nonetheless, no negative effects on the fetus have been found in patients treated with an appropriated antibiotic therapy.
- There are no reports of transmission through blood transfusions. Patients who were diagnosed with Lyme disease can donate blood 30 days after completing an appropriate antibiotic treatment.
- Lyme disease cannot be transmitted by air, food, water, or by other vectors including mosquitoes, lice, and other tick species such as the lone star tick or the dog tick.