Wednesday, November 20, 2013

Lyme Disease in California - Avoiding Ticks Where They Live

By Sandi Funke, Education Director

Yuck! When we initially scheduled our lecture on Lyme disease held earlier this fall we were worried. Would anyone come? Do folks want to be empowered by the latest research or do we collectively want to put our heads in the sand about this devastating disease? Well, folks did come and were very interested! Personally, I have been touched in so many ways by Lyme disease. My brother has suffered from the disease for many years from a tick bite most likely contracted hiking with me in Big Basin Park near Santa Cruz. Staff members have been bitten by ticks and contracted the disease in Sonoma County and in the midwest. It’s a big problem but, as it turns out, the adult ticks and nymphs that carry Lyme disease have certain habits and preferences that can help inform where and how we spend time in nature.

According to the Centers of Disease Control and Prevention Lyme disease is caused by the bacterium Borrelia burgdorferi and is transmitted to humans through the bite of infected black legged ticks. Typical symptoms include fever, headache, fatigue, and a characteristic skin rash called erythema migrans which makes a bulls eye pattern. If left untreated, the infection can spread to joints, the heart, and the nervous system. Some believe Lyme disease can also cause long term chronic symptoms, though there is no complete consensus in the medical establishment on this.

This fall Dr. Robert Lane from University of California Berkeley’s Department of Environmental Science, Policy, and Management, spoke at Pepperwood about Lyme disease, tick life cycles, and his research on the spread of the disease in California. As explained by Dr. Lane and detailed in Pest Notes - Lyme Disease in California, ticks have four life cycles: the egg, larva, nymph and adult stage. In California, only the nymph and the adult female of the western black legged tick transmit the bacterium to humans.

Unfortunately, the western black legged tick is the most abundant of the 47 species of ticks known to live in California. It is very small. The nymphs are only the size of a poppy seed and the adult females are only about 1/8 of an inch. The nymphs transmit most of the disease in California. Nymphs are found in forests and woodlands carpeted with leaf litter or fir needles. They occur within the leaf litter and crawl onto tree trunks and logs. They tend to transmit the disease from March to July.

Adult ticks occur on low vegetation most commonly in grasslands or chaparral. Strangely, they are also more abundant on the uphill margins of hillside trails. More adults are also found in the margins between different habitats. Adults transmit the disease November to July. Adults tend to be active in the early morning and late afternoon.

There are several steps we can take to avoid getting bit by a tick. When in forests and woodlands avoid sitting on logs or leaning against tree trunks - bring a chair! If you are hiking in a potentially tick infested area, stay towards the middle of trails and stick to the downhill margin of the trail. Wearing long sleeved shirts and pants and tucking in pant legs and shirt tails can also help. Dr. Lane recommends considering use of repellant - some have been shown to be up to 85% effective. You should also always do a tick check after hiking paying special attention to exposed areas of skin on arms, legs, behind ears, and on the scalp. If you have pets you should also check your pet for ticks.

It may not be possible to completely eliminate all risks of exposure to Lyme disease in California. However, we can take certain steps to reduce contact to ticks. By getting more informed we can all feel a little safer exploring and working outdoors in California.

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