Ticks grow from the egg to the adult by what is called simple metamorphosis, meaning their appearance does not change much. They emerge from the egg as a tiny tick, shed their skin some months later to become the second stage and a slightly larger tick, and then shed their outer skin one last time to become the adult tick, at which time males and females mate and large numbers of new eggs are laid. The life cycle of ticks, from egg to adult, generally takes around 2 years.
The good news, if there is any, is that the bacteria that causes Lyme Disease does not appear to enter the eggs of the tick before being laid. Therefore, the first stage ticks are not infected, as those that spread other tick-borne diseases may be. This, at least, slightly lessens the chances of being infected. The first stage ticks become infected by ingesting the blood of an infected animal, and a curious situation has been seen here that still is not well understood. In many parts of the eastern U.S. the percentage of infected ticks is very, very high - perhaps two out of three ticks are carrying Lyme Disease bacteria. However, in most of the western U.S. the percentage of infected ticks is only around one or two percent. The obvious implication with these numbers is that those who live in tick-prone areas of the eastern states are far more likely to be fed upon by an infected tick than those in the West, and thus the difference in Lyme Disease incidence between the two geographic areas.
A possible explanation for this difference in the infection rates in the ticks has to do with their choices of meals. The early stages of ticks feed primarily on small animals, particularly the White Footed Deer Mice, but in the West they also feed quite commonly on the Western Fence Lizard - also referred to as "blue belly lizards" due to the shiny blue stripes on each side of their tummies. It appears that some chemistry in the blood of these lizards kills the bacteria, and thus ends the cycle of that pathogen at that point. More to come, no doubt.
As the ticks move to the adult stage their choice for meals becomes the larger deer, dogs, or other animals, and if the ticks fed on an infected animal in their previous two life stages they will be infected as adults, and pass the bacteria into the blood of this large animal, causing it to be a carrier as well. Dogs are susceptible to Lyme Disease, and a vaccine has recently become available to prevent it in these animals. A vaccine for humans is apparently close as well, but studies are still in their early stages as of 2002, and the effectiveness in preventing human Lyme Disease is not yet known.
What are the symptoms of Lyme Disease?
Unfortunately, the symptoms of this disease are fairly erratic, in that not everyone experiences the same thing at the same time. We can speak in terms of what appear to be the "normal" symptoms though.
Stage One - from 3 days to a month after being bitten by an infected tick you feel very much like you have the flu - fever, chills, fatigue. This often is accompanied by a rash called a "bulls-eye" rash, due to its appearance as an expanding ring. The rash may not even be at the site of the bite, and later it may expand to several spots in other areas of the body.
Stage Two - may occur months later as more rashes along with dizziness, fatigue, severe pain in the joints, and shortness of breath. Another more terrible effect is possible paralysis of muscles in the face, leading to a condition called Bell's Palsy, due to damage to the nervous system. Stage Two may occur on and off for a long time, with periods where you feel much better, only to have the symptoms reoccur.
Stage Three - in a small percentage of cases the heart becomes affected and weakened, leading to more severe problems. Also, the pain and swelling of the joints becomes even more pronounced over time, leading to chronic problems there as well.
Lyme Disease is not to be confused with Tick Paralysis though. Tick Paralysis is caused by a toxin within the saliva of the feeding tick, and usually within a week after a tick has begun feeding you would feel numbing and weakness of the legs and arms, along with muscle pain. This could lead to difficulty in swallowing and facial paralysis, or possibly to worse complications if left untreated.