Ticks are parasites that ___1___
on the blood of other animals. They begin their lives as
eggs, which hatch into larvae and crawl to the tips of
grasses and other low-growing plants. They wait until
the next warm-blooded animal happens to go by, then
latch on, burrow into the skin, and begin sucking blood.
When they are ___2___
up to 10 times their normal size, they drop off their
host and spend time resting. Diseases can be spread
___3___ a feeding
tick at any stage of its life. After it burrows its head
into the skin of a host, the tick glues itself into
place and ___4___ an
anticoagulant to keep blood flowing. While the blood
flows from the host into the tick, microbes and bacteria
are exchanged.
Researches have identified a tick-spread disease ___5___
as human granulocytic ehrlichiosis ( HGE ). The symptoms
of HGE are body aches, fever, headache and nausea. HGE
also causes a significant drop in infection-fighting
white blood cells and can be potentially
life-threatening if not treated quickly. |