Tuesday, February 12, 2013

Parasites Part 7: Ticks

Ticks are arthropods (like spiders) and there are several species that exist in various parts of the country.  Although different species vary somewhat in their life cycle they all share the basic similarities.

Female ticks lay their eggs in a secluded place in the spring and can lay as many as 100-6,000 at a time depending on the species.  Within two weeks the eggs hatch and find a host-usually a bird or rodent.  After several days of feeding they drop off and become nymphs.  The nymphs remain inactive during the winter and start seeking a new host in the spring. Once they find a new host (pet, human, or wildlife) they feed and once again fall off.  At this point they become adults.  In the fall the adults find a host, again, a pet, human or wildlife, and the females feed for 8-12 days.  The adults mate while on the host, when they fall off the males die, and the females remain inactive for the winter and lay eggs in the spring, starting the cycle again.

So this is all fine and well but why are they so hard to get rid of?  There are several factors for this.  One is the ability to survive without a host.  If  tick is unable to find a host in the fall it can survive over the winter without a blood meal.   Also, some of the available tick control products don't work on all species of ticks.  In addition to this the wildlife in the area serve as a huge reservoir   Literally thousands of ticks can live on one moose or deer.  With their ability to survive, huge egg-laying capacity, and large reservoir it can nearly impossible to eradicate them.

Ticks tend to live in leaf litter and tall grass so keeping the yard trimmed and avoiding wooded areas will help limit exposure.  Contrary to popular belief ticks do not normally jump from trees to land on hosts.  However,  they are attracted to motion, heat and changes in light patterns and use these methods to crawl towards hosts passing through their area.

Ticks themselves don't cause much problem.  The bite itself is usually painless and typically causes only a mild, self-limiting local irritation on the skin.  Although they do feed on blood, usually there are not enough ticks on a pet at a time for this to be significant.  The big problem with ticks is that they can transmit a number of diseases, including tick paralysis, lyme disease, ehrlichiosis, babesia, and rocky mountain spotted fever. However, it can take several hours of feeding before transmitting disease.  Therefore, avoiding tick habitats, using appropriate tick control products, and finding and removing ticks before they attach will help prevent disease transmission.

Zoonotic potential
As most of us know, ticks can bite people as well.  Humans are also susceptible to many of the tick borne illnesses listed above.


Sara said...

Oh ticks, how I hate thee....

Sue said...

Ticks just seem creepier than almost any other insect. Yuck!