What is the life cycle of ticks that cause babesiosis?

Updated: Apr 01, 2021
  • Author: Rachel E Strength, MD; Chief Editor: Michael Stuart Bronze, MD  more...
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The I. scapularis life cycle takes 2 years to complete, beginning with egg deposition in the spring. The white-footed mouse is the primary enzootic reservoir. After feeding on infected white-footed mice, the tick larvae become infected with B. microti. The tick then develops from the larval phase to the nymphal phase. This development takes 1 year (ie, until the next spring).

Nymphs infected with B. microti may transmit the Babesia organisms to other mice or rodents or to a human host. Nymphs feed for 3-4 days on white-footed mice or other rodents and mature into adults the following fall.

Adult Ixodes tick populations are maintained in white-tailed deer. The adults mate and feed on the deer during the spring; they then deposit their eggs and die. Although rodents are infected with Babesia, the white-tailed deer does not carry the organism. B microti is transmitted from the larval phase of I. scapularis to the nymphal phase (transstadial transmission) but not transovarially. The white-footed mouse is necessary to perpetuate the Babesia organisms, and the deer is needed to perpetuate the Ixodes tick population.

Larvae, nymphs, and adult ticks may all infect humans, but the nymph is the primary vector of B. microti infection.

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