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240 CHAPTER 11

B
i d 8 Transmitted from
human-to-human
6 Tick takes via blood transfusion
a blood meal
(sporozoites introduced trophozoite
into host)
7
merozoite

i = Infective Stage
d = Diagnostic Stage
sporozoites i 1 Tick takes
a blood meal
(sporozoites introduced
into host)
sporogony
trophozoite
Tick Mouse
5
2
ookinete enters 4 Tick takes
salivary gland A a blood meal Source: Centers for Disease Control and Prevention (CDC)
(ingests gametes)
merozoite

fertilization
in gut
3
gamete
FIGURE 11-15 Babesia life cycle

practice to use heat such as a lighted match, acetone, of other tick-borne diseases are usually focused on the
petroleum jelly, or other methods to try to make the eradication of the vectors by dusting the cattle and
tick release its attachment. These latter methods are other domestic animals with an insecticide. In addition
not often effective practices for removing an embedded to the attempts to eradicate tick vectors that transmit
tick and may even kill the tick while leaving its head the disease organisms, vaccination of animals is also
imbedded in the skin. possible against the Babesia parasites.
Tick infestations and tick-borne diseases are
economically important in many breeds of domestic
animals. The development and production of innovative HUMAN EHRLICHIOSIS IN THE
tick control methods included in the life cycle of UNITED STATES
babesiosis is directed primarily toward economically
important tick-borne diseases of cattle and work What is meant by the term ehrlichiosis? Ehrlichiosis is
animals (Figure 11-15). The tick-borne protozoan the general name used to describe any of several bacterial
Babesia parasite remains a crucial consideration when diseases capable of affecting both animals and humans.
cattle industries are being broadened around the globe. These diseases are caused by organisms of the genus
In animals, Babesia canis rossi, Babesia bigemina, and Ehrlichia. On a global basis, four ehrlichial species of or-
Babesia bovis cause particularly severe forms of the ganisms are currently known to cause disease in humans.
disease that may result in a severe hemolytic anemia. The causative organism included in the four Ehrlichia
Effective control of Babesia and a considerable number species typically infect two types of white blood cells that