Lyme borreliosis or Lyme Disease is recognized in people throughout the world and there is evidence that it is increasing worldwide. It's name is derived from the town of Old Lyme, Connecticut. In the 1970's, pyisicians in the area noticed an unusual pattern of transient, recurrent joint diseases occurring mainly in children during the summer and early autumn months. After intense investigation, a new spirochete, Borrelia burgdorferi, was implicated in the causation of disease.
The majority of cases reported annually in the United States are from the northeastern and mid-Atlantic regions, however, cases are also reported in California. The causative bacterium is carried and transmitted by hard ticks (ixodid). In the northeast and Midwest, the deer tick Ixodes scapularis is the primary vector. Typically, 25-50% of the Ixodes scapularis ticks in the northeast are infected with the spirochete. The primary reservoir of Borrelia burgdorferi infection in the wildlife population of the northeast is the white-footed mouse, upon which the deer tick feeds. This tick can also bite human beings and dogs and is the major vector of transmission.
In California, the primary vectors are Ixodes pacificus, the western black-legged tick, and Ixodes neotomae, both of which feed on the dusky-footed wood rat (also called the pack rat). Typically, 1-5% of the Ixodes pacificus ticks are infected with the Lyme spirochete, while 15% of the Ixodes neotomae are infected. Note that the Ixodes neotomae tick does not feed on humans. Also, it has been noted that the California cycle is unique in that both ticks are required to perpetuate the disease in the human population.
Most dogs exhibit no signs of disease and there is little evidence that the organism causes a chronic disease analogous to that observed in humans. Acute disease in dogs is characterized by fever, lack of appetite, malaise, lethargy, lymph node enlargement, join pain, and lameness. Unlike humans, there is no skin reaction at the site of the bite.
Tetracycline antibiotic therapy is usually effective against the spirochete.
Since Lyme disease can be quite severe for humans, an inactivated vaccine has been introduced for dogs. The vaccine reportedly protects for at least 6 months. However, since the vaccine does not eliminate the primary vector, ticks, it is more appropriate to insure that your dog is not bringing into the home ticks that may harbor the spirochete. Several good products exist that help minimize ticks adhering to your dog.