LymeBlog - Protect yourself in tick habitats

Protect yourself in tick habitats
Amador Ledger Dispatch, Amador City, CA USA
By Steve Diers
Ranger/Naturalist II
Mokelumne Watershed Unit

The California Legislature has unanimously designated May as Lyme Disease Awareness Month.

"Lyme disease, which is caused by the bacterial spirochete Borrelia burgdorferi, is a public health threat of major proportions. The majority of Lyme disease cases result from bites by infected nymphal ticks that may be as small as the period at the end of this sentence. Only 14-35 percent of patients recall a tick bite.

Ticks have been called "sewers of infection." They feed primarily on birds, rodents, and deer and can transmit to humans many of the diseases carried by these animals. Hence, patients with Lyme disease may be infected with multiple pathogens. The most widely known co-infections acquired from Western Black-legged ticks are Babesia, Bartonella, Ehrlichia and Mycoplasma fermentans.

Not all pathogens have been identified. Patients with coinfections may have more severe symptoms and an extended course of illness.

According to the Centers for Disease Control, only one in 10 cases of Lyme disease is reported, which means the 23,763 cases nationally reported in 2002 reflect 237,630 actual cases. The annual incidence of Lyme disease, which accounts for 95 percent of vector-borne illnesses in the United States, has increased almost 50-fold since national surveillance began in 1982.

Birds have been identified as reservoirs of infection on the west slopes of ...

the Sierra Nevada Range. Lyme-infected ticks may be transported from Lyme-endemic areas into non-endemic areas along "flyways" of migratory birds.

Risky behavior

Activities involving a considerable degree of contact with wood resulted in greater acquisition of nymphs than those involving exposure solely to leaf litter. Time-adjusted tick-acquisition rates demonstrated that sitting on logs was the riskiest behavior, followed, in descending rank, by gathering wood, sitting against trees, walking, stirring and sitting on leaf litter, and just sitting on leaf litter.

Protect yourself if you are going to be in tick habitat

Dress appropriately: Wearing shorts into tick habitat increases the risk. Wear light colored clothing so ticks can be easily seen and removed. Tuck pants into boots and shirt into pants; pull socks over pants and wear a hat. Apply Permanone (0.5 percent Permethrin) on clothing to repel or kill ticks. When applying insect repellents on the exposed skin of adults, the repellent should contain no more than 25 percent DEET; 10 percent on the skin of children. Use pesticides in a responsible manner.

I recommend spraying one pair of pants with a repellent containing Permethrin (two hours before use) and putting an identifying mark on the inside. The treatment will remain effective after two to three launderings of the garment. Permethrin products approved for human use can be found under labels such as Duranon, Permanone and Congo Creek Tick Spray. Permethrin products approved for human use are available from REI. Also (BuzzOff brand) clothing impregnated with Permethrin can be purchased from REI.

Conclusions

People who work and play in the out-of-doors are at risk for Lyme disease. Of all tick-borne disease in California, 95 percent is Lyme. There are 48 species of ticks in California and nine that can carry disease. The Western Black-legged tick may harbor at least a dozen microbes.

Most cases of Lyme disease arise from tick exposures in late spring and early summer.

Black legged nymphal ticks, about the size of a poppy seed, account for most of the Lyme disease transmission in California. The infection rate range in nymphs is 0 to 41 percent.

Nymphs are found April to July in moist leaf litter in oak woodland, mixed chaparral, madrone forests, redwood forests and fir needle duff.

Adult ticks are found on trails, 80 to 90 percent are found in shaded moist ecotones (north facing) on the uphill side of a trail October to June, and peak in December to February. The pack rat is a reservoir for Borrelia burgdorferi in the north coast area and birds are the reservoir on the west slope of the Sierras.

Proper tick removal requires patience. It is more important to get prompt medical treatment than to get the tick tested. Of people shown to have Lyme disease, 70 percent don't remember a bite.

About 38 percent of the individuals bitten by an infected blacklegged tick exhibit an erythema migrans ("Bull's-eye" rash), and 70 percent of the rashes are atypical and do not occur on the bite site. Lyme is diagnosed clinically. Treatment costs increase with delayed diagnosis. On average it takes 22 months and seven doctors to get diagnosed. The current state of laboratory testing for Lyme disease is very poor. The situation has led many people to be misdiagnosed and delayed proper treatment. Specimens should be sent to reliable labs.

Once an individual is infected with Lyme disease, proper treatment of antibiotics is recommended immediately. Treatment should be continued until all the symptoms are gone.

The infecting Borrelia burgdorferi spirochete hides in tissue cells. The antibiotic cannot penetrate the cell wall. The only way to kill the bacteria is to have an antibiotic in the body as the cell is dividing (every 28 to 30 days).

Once an individual is infected with Lyme disease, he or she has a six- to eight-week window of opportunity to receive proper treatment to prevent chronic problems.

Lyme disease can be a chronic illness with persisting infection. Widespread denial of Lyme disease leaves undiagnosed and untreated patients to progress to a late stage of the disease. Long-term antibiotic treatment is common in cases with persistent clinical symptoms.

Total cases of Lyme disease in the U.S. may be as high as 2 million. Ignorance, lack of concern and under reporting continue to complicate the problems of recognized Lyme disease.

Education of the public and the medical community is the most important way to reduce the risk and increase the awareness of tick-borne diseases.