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.
