Prevention is key to Lyme disease concerns
Recently, there has been a great deal of attention to Lyme disease in the newspapers. In order for the public to view this disease rationally, it is important that, in addition to the clinical aspects of this entity, the public and medical community appreciate the incidence of Lyme disease in California and Los Angeles County. According to the County of Los Angeles Department of Public Health, there were 89 cases of Lyme disease reported in the State of California in 2005, and the total number of Lyme disease cases has averaged around 100 per year for the last decade. During this same period in Los Angeles County there have been from zero to 8 cases reported per year, with 8 cases confirmed in 2005. This corresponds to one case for every two million Angelinos per year. Most of the reported cases in Los Angeles County occur in individuals who were exposed to Lyme disease outside the county-usually in the Northeastern U.S. In low risk areas, like Los Angeles County, incorrect diagnosis and treatment can often occur. The reality is that for Malibu residents, Pacific Coast Highway is far riskier to one’s health than the potential for Lyme disease.
Lyme disease is caused by the spirochete bacteria Borrelia burgdorferi. The bacteria is transmitted by ticks, specifically Ixodes damini, I. pacificus, I. ricinus and I.scapuliaris. The tick life cycle starts as a lymph stage that matures to the larval stage with the primary host being the white-footed mouse. Ticks then mature to the adult stage whose host is the white-tailed deer. Lyme disease can be transmitted to humans and other mammalian hosts by the nymph (1-2mm in size) and adult stages. It takes approximately 24-36 hours for a tick to transmit the infection through feeding, so prompt removal of ticks from both your pet and yourself is important. There is no documentation that a person can contract Lyme disease from direct contact with wild or domestic animals.
In humans, the most common initial symptom (50 percent of cases) is a rash called erythema migrans. The rash typically takes three days to one month to develop at the site of the tick bite. It is important, however, to understand that a similar rash may develop as a result of an allergic reaction to tick saliva, but this reaction is usually immediate. The most common sites of tick bites are in hairy areas of skin, including the groin, inner thigh, trunk and armpits.
In animals, the most common clinical signs are episodic lameness and fever. Dogs may be exposed to the disease, but never exhibit any signs. A survey of dogs in New England showed 90 percent of dogs with antibodies indicating exposure, and only 4 percent of dogs with clinical signs of illness. If you are concerned that your animal may be displaying signs of Lyme disease, a screening test may be done with your veterinarian to determine its exposure. The disease in animals is treated with a 3-4 week course of antibiotics. In a very small percentage of infections, kidney problems may occur that respond poorly to antibiotic therapy.
Because the bacterium is not transmitted immediately after attachment, the most effective means of prevention is to examine yourself and your pet regularly for ticks and remove them immediately. Topical insecticides such as Frontline Plus(c) or Preventic(c) collars may be used on your dogs to aid in prevention. Insect repellents containing DEET should be used on humans if frequenting tick-infested areas. Long-sleeved shirts and hats should be worn when hiking, pant-legs should be tucked into boots and shirts into pants. After hiking, clothing should be removed and washed immediately, and you should examine yourself and remove ticks by grabbing them close to the skin surface and pulling out gently.
If you are concerned about exposure to Lyme disease, consult your physician and/or veterinarian. For more information about Lyme disease in California, you may contact the California Department of Health Services (www.dhs.ca.gov).
Rich Johnson, M.D., Gary Green, MD
Pacific Palisades Medical Group
Clinical Professors of Family Medicine
David Geffen School of Medicine at UCLA
Dana DePerno, DVM, Dean Graulich, DVM, Lisa Newell, DVM
Malibu Coast Animal Hospital