How can I protect myself and my family from ticks and Lyme Disease?
DEFINITION: Lyme Disease is an infectious disease caused by a spirochete-form bacterium (Borrelia burgdorferi), and was first identified in the 70's in children in Lyme, Connecticut who exhibited arthritis-like symptoms. The primary means of transmission to humans in the east is the deer tick, AKA black-legged tick, (Ixodes scapularis) which harbors the bacterium in its gut.
There are reports that Lyme Disease can also be transmitted by biting flies, although this is rare.
OCCURRENCE: The most significant areas of infection are on the eastern seaboard, from Massachusetts to Maryland, with other hotspots in the Great Lakes area and in a few localities on the Pacific coast. However, isolated cases have been reported in virtually all states, including Alaska and Hawaii.
Anybody who works outside in these areas is at danger of infection.
LIFE CYCLE: The life cycle of the bacterium involves deer, white-footed mice, ticks and humans (other animals can be involved, but these are the most relevant to us). The ticks apparently prefer to feed on deer and then drop off and lay their eggs in the spring in moist litter in the woods or overgrown grassy areas. The eggs hatch into larvae, which are not yet infected. The larvae attach to the mice, which may be infected, and become infected by the host mouse.
When the larvae are finished feeding, they drop off the mice in late summer, and develop into nymphal ticks which retain the bacterium if the larvae were infected. The nymphs go dormant for the winter and then, in early spring start looking for a new host, which may be human.
The major threat to humans is the nymph, which feeds and infects in late spring to summer, usually May to July. The nymph is tiny and hard to see when it's attached, so it may not be noticed.
The nymph molts into an adult tick in the fall. The adult then goes looking for a big meal, typically a deer or a human and can also infect at this stage. However, the adult tick is easier to see because it's bigger (not huge, but detectable). When it's finished eating, it drops off, the female lays eggs, and the cycle is off again.
SEASONAL ISSUES: The major danger of infection is in late spring and summer when the tiny nymph is feeding on people, but you still need to be vigilant in the fall when the adult tick is around.
There are also some interesting annual/biennial connections between oak trees, acorns, ticks, mice and gypsy moths. Ticks in the east are commonly found in deciduous, oak forests. Studies indicate that oaks have a 2 to 5 year cycle where one year a large number of acorns are formed, followed by leaner years. The deer and the mice thrive when they've got lots of acorns to eat, and the ticks are happy because there are lots of hosts (deer and mice). What it all means is that the frequency of Lyme Disease infections seems to be higher a year or two after there are lots of acorns (gypsy moths are less frequent because mice eat the moth...